Another minor routine update 0.0.6 of gettz arrived on CRAN just now.

gettz provides a possible fallback in situations where Sys.timezone() fails to determine the system timezone. That happened when e.g. the file /etc/localtime somehow is not a link into the corresponding file with zoneinfo data in, say, /usr/share/zoneinfo. Since the package was written (in the fall of 2016), R added a similar extended heuristic approach itself making the package a little less relevant.

This release reflects several rounds of updates to the continuous integration setup, some URL updates, as well as some updates to packaging including use of Authors@R in DESCRIPTION. As with the previous releses: No functional changes, no new code, or new features.

Thanks to my CRANberries, there is a diff to the previous release. Questions, comments etc should go to the GitHub issue tracker off the GitHub repo.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. If you like this or other open-source work I do, you can sponsor me at GitHub.

25 Aug 2026 2:01pm GMT

In 2025 I was honored to be selected for the first cohort of Sovereign Tech Fellows, a program by Germany's Sovereign Tech Agency to improve the resilience of the open source ecosystem by supporting maintainers directly (complementing their existing support for larger FOSS organizations). Back in 2025, I was only working very limited hours - however, this has changed in 2026.

For the second half of 2026, I am working again as a Sovereign Tech Fellow, but this time with significantly increased hours. After finishing my PhD, I do have time now for new tasks (and new jobs!), and the fellowship presents an amazing opportunity to really advance projects that I maintain or am part of. This also has a very nice effect on contributors and bug reporters, as their feedback gets addressed a lot faster. With some luck, this ultimately will help finding new (co)maintainers for projects as well (although in the age of AI, a lot of how open source used to work is much more uncertain, but that is a matter for a different blog post).

The fellowship is time-limited, so I am intending to make the time I currently have count!

So, what's planned?

I am involved in many projects, but three of them will be getting attention as part of the fellowship. I know I am notoriously slow at blogging, but expect more details on each of them very soon. Here's an overview:

Freedesktop.org, Specifications and Organization

I maintain the Freedesktop Specifications, which is an area of Freedesktop that has traditionally been a bit chaotic. This "worked" in the past, because Freedesktop was never intended to be a formal standards body, but more a shared space where people could throw a lot of code and ideas over the wall and see what sticks and what people can collaborate on.

While I very much love the spirit of this and want to keep it in some form, we definitely would benefit not just from more formalization and better procedures, but also from better organization of the specifications in general. A lot of conflicts can be avoided by that. I will work on improving procedures, crunching through the (lots!) of pending bug reports and MRs, and to make the specifications site better searchable and accessible (similar to how Mozilla's MDN presents information, but I am not sure if we will get quite that far). I also intent to add a compatibility matrix for specifications, so if a desktop opts out of any one of them (or does not implement them yet) that fact is documented and authors of applications know what they can expect. This will allow us to move a lot faster and avoid a lot of conflict, because there is no implicit assumption that "everybody will implement everything" anymore (which has never been quite true anyway).

Hopefully, this will ultimately result in a Freedesktop that is both a lot more useful for application authors who want to bring their project to Linux, as well as developers of desktop environments who need to see which specifications are available and which ones are current.

In addition to that, I have also worked on a Freedesktop.org website refresh, which is pretty much done in its first iteration (pending sysadmin action). The aim there is to have a more official website, separate from user-contributed wiki content, that showcases what Freedesktop is and which projects are using it for hosting. Once the new website is live, I will also review every page again, archive dead projects in their own section and reorganize the software and specifications directory. Those sections are severely outdated and are missing recent efforts from the community, while still containing long-dead old projects (remember HAL? ).

AppStream

A lot of extra maintenance work will be (has been!) done on it. This includes things such as JPEG-XL support (blog post soon), sandboxed media processing, support for newer specification additions, better OARS integration (and potentially migrating it to fd.o infrastructure), improvements and API stabilization for libappstream-compose and a lot of bugfixing and resolution of issues found by AI code review.

AppStream was originally designed to parse only trusted data from vetted Linux distribution sources - this is no longer the case in today's world and in the way Flatpak uses it, so we need to increase resilience of the project.

I am also exploring a project that could vastly improve search accuracy for AppStream. Stay tuned for that.

PackageKit & System Upgrades

Many years ago, people thought we would all migrate to atomic Linux distributions and slowly not need PackageKit anymore. This has not turned out to be the case, and there are still plenty of reasons to use a package-based OS, especially in development environments. At the same time, PackageKit has been basically the same for years, and its older architecture is beginning to show. It being a daemon who's literal job it is to modify the entire system also makes it one of the most security-sensitive components that a Linux system can have, while simultaneously making it near-impossible to sandbox.

My plan is to create PackageKit 2.0 by building on the great foundation of PackageKit 1.0, but modernizing it. This will include simplifying its code and removing a bunch of features that have no more use in modern desktops, while also adding some features that PackageKit never had but that would be useful to expose to frontends (still no to interactivity an terminal-progress forwarding though!). PK 2.0 will also allow me to solve a few design issues that have been worked around in the past, by replacing them with better solutions. This will be a painful transition, as PackageKit 2.0 will break all interfaces PackageKit has - and those interfaces have been frozen for more than a decade. However, I do fully expect this change to be worth the effort.

In addition to that, I intend to look into the offline-update procedure again and improve it. The current multi-reboot operation comes with downsides, that newer systemd features such as soft-reboot can alleviate. The end result should be a much smoother, less annoying offline-update experience for users (I especially want to get rid of updates running on system startup, which I consider quite bad from a usability perspective). The new behavior is in the early drafting stages and may need direct support from systemd. I will share more about it once I can.

That's a lot of tasks!

Yes! I will see how far I get. I am moving project-by-project though, to allow me to focus on one project at a time, rather than scattering my attention continuously. Amazingly, this means that the major tasks for AppStream are already almost done, and we are nearing the 1.2.0 release. AppStream got priority, because the new Freedesktop Flatpak runtime will be released soon, and because I want FlatHub/Flatpak to have access to the new AppStream release sooner. Freedesktop and PackageKit are next on the task list.

Either way, a lot of progress is coming - if you have any feedback or want to help out, please don't hesitate to reach out! All work is happening fully in the open, so you can also chime in on the respective GitHub/GitLab tasks .

You can also expect blog posts about key features or interesting changes, so stay tuned!

24 Aug 2026 9:00pm GMT

A new release of gaussfacts package arrived on CRAN - the first in pretty much exactly a decade! gaussfacts provides a fortunes-inspired function to display randomly-chosen facts about Carl Friedrich Gauss, based on the collection curated by Mike Cavers via the gaussfacts web site (with an archive.org link it case it vanishes again). Each call of gaussfact() displays another (randomly chosen, or indexed) fact.

An example:

> gaussfacts::gaussfact(9)
Gauss once played himself in a zero-sum game and won $50. 
> 

This releases, as detailed below, accumulates a number of smaller maintenance changes including switching to Authors@R. Functionality has not changed. Oddly enough, it appears that I did not blog about the package when I created it in August 2016. So to (partially) make up for that, the NEWS for all three releases follow.

Changes in version 0.0.3 (2026-08-23)

• Several rounds of continuous integration maintenance and enhancements

• Additional README.md badges

• Updates to DESCRIPTION as CRAN requirements change

• A duplicate data entry has been removed (Tim Pokart in #4)

• Documentation prefers https URLs

• Updated continunous integration multiple times

• Correct man page removing an erroneous duplicate word

Changes in version 0.0.2 (2016-08-03)

• Support 'ind' argument to reference by position

• Clean-up encoding and support extended character set (#2 closes #1)

• Updated continunous integration (#3)

Changes in version 0.0.1 (2016-06-19)

• Initial version and CRAN upload

Thanks to my CRANberries, there is a diff to the previous release. Questions, comments etc should go to the GitHub issue tracker off the GitHub repo.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. If you like this or other open-source work I do, you can sponsor me at GitHub.

24 Aug 2026 7:04pm GMT

Imagine you rent office space for a three-day event. You quickly set up a few Ethernet switches and tape some cables on the floor to get everyone online. Unfortunately, Stan, your clumsiest coworker, kicks out a cable every time he gets up for coffee. You could add extra cables, but then you'd get a broadcast storm: Ethernet packets that loop and multiply until nothing else gets through.

That's where the spanning tree protocol (STP) comes in. STP blocks just enough of your spare cables to leave a loop-free tree. When Stan strikes again, it rebuilds the tree in a second, leaving some time for Blobby, your one-person support crew, to reconnect the cable. See for yourself: the diagram below runs a real STP implementation in your browser!

:demo

A1 @0,0 prio=4096
A2 @0,1
A3 @0,2
A4 @0,3

B1 @1,0 prio=8192
B2 @1,1
B3 @1,2
B4 @1,3

C1 @2,0 prio=8192
C2 @2,1
C3 @2,2
C4 @2,3

A1 -- A2 hazard=0
A2 -- A3 hazard=0
A3 -- A4 hazard=0
B1 -- B2
B2 -- B3
B3 -- B4
C1 -- C2 hazard=0
C2 -- C3 hazard=0
C3 -- C4 hazard=0

A1 -- B1 cost=10
B1 -- C1 cost=10
A4 -- B4 cost=20
B4 -- C4 cost=20

Leo @-0.3,0.7 proto=none icon=👦🏻
Mia @-0.3,1.3 proto=none icon=👧🏽
Joy @0.3,0.7  proto=none icon=👱🏻‍♀️
Roy @0.3,1.3  proto=none icon=👨🏾
A2 -- Leo hazard=0 A2:edge
A2 -- Mia hazard=0 A2:edge
A2 -- Joy hazard=0 A2:edge
A2 -- Roy hazard=0 A2:edge

Max @-0.3,1.7 proto=none icon=👨🏽
Zoe @-0.3,2.3 proto=none icon=👩🏾
Ada @0.3,1.7  proto=none icon=👵🏾
Amy @0.3,2.3  proto=none icon=👩🏼
A3 -- Max hazard=0 A3:edge
A3 -- Zoe hazard=0 A3:edge
A3 -- Ada hazard=0 A3:edge
A3 -- Amy hazard=0 A3:edge

Eli @0.7,0.7 proto=none icon=👦🏼
Jay @0.7,1.3 proto=none icon=👨🏻
Kai @1.3,0.7  proto=none icon=🧑🏽
Ben @1.3,1.3  proto=none icon=👱🏼
B2 -- Eli hazard=0.2 B2:edge
B2 -- Jay hazard=0.2 B2:edge
B2 -- Kai hazard=0.2 B2:edge
B2 -- Ben hazard=0.2 B2:edge

Ava @0.7,1.7 proto=none icon=👩🏻
Lea @0.7,2.3 proto=none icon=🧑🏾‍🦱
Ivy @1.3,1.7  proto=none icon=🧕🏽
Rex @1.3,2.3  proto=none icon=👴🏿
B3 -- Ava hazard=0.2 B3:edge
B3 -- Lea hazard=0.2 B3:edge
B3 -- Ivy hazard=0.2 B3:edge
B3 -- Rex hazard=0.2 B3:edge

Ana @1.7,0.7 proto=none icon=👩🏿
Eve @1.7,1.3 proto=none icon=👧🏼
Abe @2.3,0.7  proto=none icon=🧓🏿
Ian @2.3,1.3  proto=none icon=🧔🏾
C2 -- Ana hazard=0 C2:edge
C2 -- Eve hazard=0 C2:edge
C2 -- Abe hazard=0 C2:edge
C2 -- Ian hazard=0 C2:edge

Ned @1.7,1.7 proto=none icon=👨🏼‍🦳
Lou @1.7,2.3 proto=none icon=🧑🏿
Fay @2.3,1.7  proto=none icon=👧🏻
Sue @2.3,2.3  proto=none icon=👩🏽‍🦰
C3 -- Ned hazard=0 C3:edge
C3 -- Lou hazard=0 C3:edge
C3 -- Fay hazard=0 C3:edge
C3 -- Sue hazard=0 C3:edge

The basics

Designed in the '80s, the spanning tree protocol has evolved into a "rapid" flavor (RSTP) and a "VLAN-aware" variation (MSTP).¹ Any sound-minded network engineer knows there are better alternatives, like BGP EVPN VXLAN. Yet, because any switch speaks it, the venerable spanning tree protocol still fills a niche.

We focus on RSTP: it replaced the original protocol in 2004. To eliminate network loops, RSTP implements a complex state machine. Timers, link state changes, and the link-local control frames a bridge receives from its neighbors drive its transitions. These Ethernet frames are the Bridge Protocol Data Units (BPDUs). You can watch them in action below: hit the "Start" button.

:protocol rstp
:tx-hold 10

A1 @0,1
C11 @1,0 prio=4096 icon=🌳
C12 @1,2 prio=4096 icon=🌳
C21 @2,0 prio=4096 icon=🌳
C22 @2,2 prio=4096 icon=🌳
A2 @3,1

H1 @0,0.2 proto=none icon=💻
H2 @0,1.8 proto=none icon=🖨️
H3 @3,0.2 proto=none icon=📠
H4 @3,1.8 proto=none icon=📺

A1 -- C11
A1 -- C12
A2 -- C21
A2 -- C22
C11 -- C12
C11 -- C21
C11 -- C21
C11 -- C22
C12 -- C21
C12 -- C22
C21 -- C22
A1 -- H1 A1:edge
A1 -- H2 A1:edge
A2 -- H3 A2:edge
A2 -- H4 A2:edge

After some time, the topology converges to a tree: from the root C11, there is a path to each bridge² and no loop. In the upper right corner, the interface displays a tree icon 🌳 followed by the time it took to reach this state. Cut a link and see how the protocol finds an alternate path to reach C12 in less than a second. You can stop the simulation, move it forward step by step, reset it to its initial state, or slow it down with the "snail" mode 🐌. Don't worry about all the displayed information: I explain it later.

All examples run in your browser, powered by MSTPD-an open-source user-space³ implementation of RSTP.⁴

Historical interlude

Radia Perlman, an inductee of the Internet Hall of Fame in 2014, summarized the ancestor of STP she invented at DEC with this poem, later included in a US patent:

I think that I shall never see
A graph more lovely than a tree.
A tree whose crucial property
Is loop-free connectivity.
A tree which must be sure to span
So packets can reach every LAN.
First, the root must be selected.
By ID, it is elected.
Least cost paths from root are traced.
In the tree, these paths are placed.
A mesh is made by folks like me,
Then bridges find a spanning tree.

― Radia Perlman, Algorhyme.

Electing the root bridge

To build a tree, RSTP first elects the bridge with the lowest bridge identifier as the root bridge. The bridge identifier combines the priority and the MAC address: 8192.6e:2b:10:a0:5f:29.

In the example below, S1 and S2 have priorities of 4,096 and 8,192: S1 becomes root. S4 has a priority of 12,288, while S3 keeps the default priority of 32,768:⁵ S4 becomes root. S5 and S6 don't have a specific priority, so the lowest MAC address wins and S5 becomes root.

:protocol rstp

S1 @0,0 prio=4096
S2 @0,1 prio=8192
S1 -- S2

S3 @1,0
S4 @1,1 prio=12288
S3 -- S4

S5 @2,0
S6 @2,1
S5 -- S6

Initially, each bridge advertises itself as root:⁶

Spanning Tree Protocol
    Protocol Identifier: Spanning Tree Protocol (0x0000)
    Protocol Version Identifier: Rapid Spanning Tree (2)
    BPDU Type: Rapid/Multiple Spanning Tree (0x02)
    Root Identifier: 8192.02:00:00:01:00:01
    Bridge Identifier: 8192.02:00:00:01:00:01

Once a bridge receives a BPDU advertising a better root bridge, it propagates this new information to its neighbors.

Spanning Tree Protocol
    Protocol Identifier: Spanning Tree Protocol (0x0000)
    Protocol Version Identifier: Rapid Spanning Tree (2)
    BPDU Type: Rapid/Multiple Spanning Tree (0x02)
    Root Identifier: 4096.02:00:00:00:00:00
    Bridge Identifier: 8192.02:00:00:00:00:01

Assigning roles to ports

The second step is to assign a role to each port. RSTP defines five roles, each denoted by a letter:

• root (R),
• designated (D),
• alternate (A),
• disabled (X), or
• backup (B).⁷

Each non-root bridge chooses its root port, the one with the lowest-cost path to the root. Unless you override it, each bridge derives the link cost from the speed: 20,000 for 1 Gbps. In case of equality, the lowest port identifier wins.

Each remaining port becomes a designated port if the BPDU it sends is "better" than the BPDU it receives. Otherwise, it becomes an alternate port. Later, if the root port goes down, the "best" alternate port becomes the new root port. The tiebreakers for the best BPDU are:

1. the lowest root bridge identifier,
2. the lowest accumulated cost to the root,
3. the lowest bridge identifier, and
4. the lowest port identifier.

:protocol rstp

S1 @1,0  prio=4096 icon=🌳
S2 @0,1
S3 @2,1

S1 -- S2
S1 -- S3
S1 -- S3
S2 -- S3

In the example above, after convergence, S1 is the root bridge because it has a priority of 4,096, while the other bridges have a priority of 32,768. All its ports are designated ports because the accumulated cost to the root is 0.

S2's port facing S1 becomes a root port because it has the lowest accumulated cost to the root-20,000 vs 40,000. S3 has two ports facing S1, and the one with the lowest port identifier becomes the root port-0x8000 vs 0x8001. The other candidate is an alternate port because the remote port on the link sends a better BPDU, with an accumulated cost of 0. On the segment between S2 and S3, S2's port wins: while both bridges have the same accumulated cost to the root (20,000), S2's bridge identifier is smaller-32768.02:00:00:00:00:01 vs 32768.02:00:00:00:00:02.

Spanning Tree Protocol
    Protocol Identifier: Spanning Tree Protocol (0x0000)
    Protocol Version Identifier: Rapid Spanning Tree (2)
    BPDU Type: Rapid/Multiple Spanning Tree (0x02)
    Root Identifier: 4096.02:00:00:00:00:00
    Root Path Cost: 20000
    Bridge Identifier: 32768.02:00:00:00:00:01
    Port identifier: 0x8002

If you cut the active link between S1 and S3, S3 promotes the "best" alternate port to root port. If you also disable the second link, S3 chooses the remaining alternate port as a root port. But if you disable the link between S1 and S2, S2 needs a bit more work to elect a new root port because it does not have an alternate port.

Unless a specific event happens, designated ports send BPDUs every 2 seconds.⁸ If a bridge does not receive BPDUs from its neighbor for 3 consecutive hello periods, it considers the neighbor dead and removes the port information.

Port state transition

Each port can have one of three states. The diagram displays a background color for each state:

• discarding (red),
• learning (yellow), or
• forwarding (green).

A root port transitions automatically to the forwarding state. An alternate port stays in the discarding state. A designated port has two options to transition from the discarding state to the forwarding state:

• If the port is an edge port, either through configuration or because the remote device does not speak any flavor of STP, the bridge assumes it won't participate in the protocol and cannot create a loop. In this case, the designated port immediately transitions to the forwarding state.
• Otherwise, it sends a proposal to its downstream neighbor. If the remote bridge agrees that the received BPDU is "better" than any other BPDU stored for other ports, it elects the receiving port as its root port and starts the synchronization process: it transitions all non-edge non-synced designated ports to the discarding state to avoid a loop. Then, it sends back an agreement. Upon receiving the agreement, the peer designated port transitions to the forwarding state.⁹

:protocol rstp

S1 @1,0 prio=4096 icon=🌳
S2 @1,1
S3 @0,2
S4 @2,2
S5 @0,3 prio=8192 icon=🪾
S6 @2,3
H1 @0,1.2   proto=none icon=🖨️
H2 @2,1.2   proto=none icon=📠
H3 @2.5,1.3 proto=none icon=📺
H4 @2.5,2.3 proto=none icon=💻

S1 -- S2
S2 -- S3
S2 -- S4
S3 -- S5
S4 -- S6
S4 -- S3
S5 -- S6

S3 -- H1 S3:edge
S4 -- H2 S4:edge
S4 -- H3 S4:edge
S6 -- H4 S6:edge

In the topology above, H1, H2, H3, and H4 are end devices not participating in the protocol. We configure the ports they connect to as edge ports, so these ports immediately move to the forwarding state.

Use the "step" button to move the simulation forward. The clock moves to 1 second. Step again and S1 and S2 send a proposal to each other. Here is the proposal from S2:

Spanning Tree Protocol
    Protocol Identifier: Spanning Tree Protocol (0x0000)
    Protocol Version Identifier: Rapid Spanning Tree (2)
    BPDU Type: Rapid/Multiple Spanning Tree (0x02)
    BPDU flags: 0x4e, Agreement, Port Role: Designated, Proposal
        0... .... = Topology Change Acknowledgment: No
        .1.. .... = Agreement: Yes
        ..0. .... = Forwarding: No
        ...0 .... = Learning: No
        .... 11.. = Port Role: Designated (3)
        .... ..1. = Proposal: Yes
        .... ...0 = Topology Change: No
    Root Identifier: 32768.02:00:00:00:00:01
    Root Path Cost: 0
    Bridge Identifier: 32768.02:00:00:00:00:01
    Port identifier: 0x8001

S1 ignores it: its own root identifier is lower. When S2 receives a similar proposal from S1, it accepts S1 as its root bridge. It also elects the port to S1 as the root port and starts the synchronization process. The two designated ports are already discarding, so no change here. Step again and S2 sends two BPDUs to S1. In one of them, the agreement bit is 1 and the proposal bit is 0. It also shows that S2 accepted S1 as the root bridge and its root port is now in the forwarding state. When receiving this BPDU, S1 transitions its own designated port to the forwarding state. From this point, the link between S1 and S2 forwards user traffic.

Spanning Tree Protocol
    Protocol Identifier: Spanning Tree Protocol (0x0000)
    Protocol Version Identifier: Rapid Spanning Tree (2)
    BPDU Type: Rapid/Multiple Spanning Tree (0x02)
    BPDU flags: 0x79, Agreement, Forwarding, Learning, Port Role: Root, Topology Change
        0... .... = Topology Change Acknowledgment: No
        .1.. .... = Agreement: Yes
        ..1. .... = Forwarding: Yes
        ...1 .... = Learning: Yes
        .... 10.. = Port Role: Root (2)
        .... ..0. = Proposal: No
        .... ...1 = Topology Change: Yes
    Root Identifier: 4096.02:00:00:00:00:00
    Root Path Cost: 20000
    Bridge Identifier: 32768.02:00:00:00:00:01
    Port identifier: 0x8001

Let's look at what happened to S5. Reset the simulation and step twice. S5 exchanges BPDUs with both S3 and S6. Since S5 has a lower root identifier than S3 and S6, it stays the root bridge, while S3 and S6 accept the proposal and elect their root ports. S3 and S6 start the synchronization process. S6's port to H4 stays up because this is an edge port. Move one step. Both S3 and S6 send an agreement back to S5, which transitions both designated ports to the forwarding state. Yet, the link between S5 and S3 keeps discarding user traffic! If you look carefully, S3's port toward S5 is now a designated port, not a root port. During the same step, S3 also receives a better BPDU from S2 with S1 as the root bridge. It elects its port to S2 as the root port and downgrades the port to S5 to a designated port, which stays in the discarding state.

On the next step, things get a bit tricky. S3 sends a proposal to S5:¹⁰

Spanning Tree Protocol
    Protocol Identifier: Spanning Tree Protocol (0x0000)
    Protocol Version Identifier: Rapid Spanning Tree (2)
    BPDU Type: Rapid/Multiple Spanning Tree (0x02)
    BPDU flags: 0x4f, Agreement, Port Role: Designated, Proposal, Topology Change
        0... .... = Topology Change Acknowledgment: No
        .1.. .... = Agreement: Yes
        ..0. .... = Forwarding: No
        ...0 .... = Learning: No
        .... 11.. = Port Role: Designated (3)
        .... ..1. = Proposal: Yes
        .... ...1 = Topology Change: Yes
    Root Identifier: 4096.02:00:00:00:00:00
    Root Path Cost: 40000
    Bridge Identifier: 32768.02:00:00:00:00:02
    Port identifier: 0x8002

S5 elects S1 as its root bridge and the port toward S3 as its root port. It starts its synchronization process, but the designated port to S6 does not move into the discarding state. Why? That port stays a designated port and its neighbor S6 had already sent an agreement on the link, so the port keeps its synced status.

Now, let's step back to look at what happens to S6. At this point, S6 believes S5 is the root bridge. Step once and S4 sends a new proposal to S6. S6 accepts the proposal, elects S1 as the root bridge and the port to S4 as its root port. The role of the port facing S5 changes: from a root port, it becomes a designated port. Because its peer keeps advertising an inferior BPDU on the link, this port becomes disputed and moves to the discarding state. The root port transitions to the forwarding state and the link starts forwarding immediately because S4's designated port is already in the forwarding state. If we step one more time, S5 and S6 exchange two BPDUs. The one from S5 is better because of its lower bridge identifier. S5's port stays a designated port, while S6 downgrades its own port to an alternate port.

Let's rewind one last time from the start: cut the link between S1 and S2, run the simulation until the topology is stable, stop the simulation, and restore the link between S1 and S2. During the first step, S1 and S2 exchange proposals. S2 elects S1 as the root bridge instead of S5 and the port to S1 as the root port. It downgrades the previous root port to a designated port and moves it into the discarding state. The other designated port stays synced and keeps its forwarding state. At the next step, S2 sends an agreement to S1 and the link between them starts forwarding user traffic. It also sends a proposal to S3, but not to S4. Instead, it sends a regular BPDU to S4. S4 still elects S1 as its root bridge and the port to S2 as its root port. It demotes its previous root port, the one to S3, to a designated port, which transitions to the discarding state because of the root port change. The other alternate port, to S6, also becomes a designated port and stays in the discarding state. The new root port moves to the forwarding state. On the next step, S4's port to S3 settles as an alternate port after receiving a "better" BPDU from S3.

RSTP is a giant state machine split into smaller ones: bridge detection, port information, port protocol migration, port role selection, port role transitions, port receive, port state transitions, port timers, port transmit, and topology change. Some of them are per bridge, some per port. Each bridge runs an instance. Time, operational port state changes, and the BPDUs it receives from other instances drive the transitions. Being event-driven makes RSTP more efficient but also more difficult to understand.

Placeholder for the Port Information state machine extracted from IEEE 802.1Q-2005, page 182. Pending IEEE authorization for reproduction, this is the blueprint for the Western Australian Government Railways class Msa Garratt articulated steam locomotive.

Topology change notification

A bridge populates a MAC address table: it associates each source MAC address with the port that last received it. When forwarding an Ethernet frame, it looks up this table to choose the right port.¹¹ When a link fails, a connected fridge reachable through one port may become reachable through another one. The affected bridges should flush the MAC addresses they learned, because these entries may now be wrong.

For this purpose, RSTP implements topology change notifications using a flooding mechanism. When a non-edge port transitions to the forwarding state, a bridge generates BPDUs with the topology change (TC) bit set. It sends them to all the non-edge designated ports and to the root port. It also flushes the MAC address table on these ports. When a bridge receives such a BPDU, it propagates the notification to all non-edge designated ports and the root port, except the one the notification came from. It also flushes the MAC address table on these ports. In the examples, the BPDUs with the TC bit set to 1 have a red circle.

:protocol rstp

S1 @1,0 prio=4096 icon=🌳
S2 @0,1
S3 @1,1
S4 @2,1
S5 @1,2
LPT @0.1,2 proto=none icon=🖨️

S1 -- S2
S1 -- S3
S1 -- S4
S2 -- S3
S2 -- S5
S4 -- S5
S5 -- LPT S5:edge

Start the simulation and wait a few seconds for the topology to settle. Stop the simulation and disable the link between S2 and S5. S5 elects the port facing S4 as the root port, which transitions immediately to the forwarding state. Step once and S5 emits a BPDU with the TC bit set to 1:

Spanning Tree Protocol
    Protocol Identifier: Spanning Tree Protocol (0x0000)
    Protocol Version Identifier: Rapid Spanning Tree (2)
    BPDU Type: Rapid/Multiple Spanning Tree (0x02)
    BPDU flags: 0x79, Agreement, Forwarding, Learning, Port Role: Root, Topology Change
        0... .... = Topology Change Acknowledgment: No
        .1.. .... = Agreement: Yes
        ..1. .... = Forwarding: Yes
        ...1 .... = Learning: Yes
        .... 10.. = Port Role: Root (2)
        .... ..0. = Proposal: No
        .... ...1 = Topology Change: Yes
    Root Identifier: 4096.02:00:00:00:00:00
    Root Path Cost: 40000
    Bridge Identifier: 32768.02:00:00:00:00:04
    Port identifier: 0x8002

S4 receives this BPDU. It flushes the MAC address table on the port facing S1: while LPT was previously reachable through this port, it is now reachable through S5 instead. Step once. S4 sends S1 a BPDU with the TC bit set to 1. When S1 receives this BPDU, it flushes the MAC address table on the ports facing S2 and S3. Step once and S1 sends a notification to S2 and S3. Step once again and S2 sends a notification to S3, while S3 does nothing because the port toward S2 is an alternate port. S3 does not flush any MAC address table: LPT is still reachable through its port to S1.

If you step a bit more, you will see that some of the periodic BPDUs keep the TC bit set to 1. Each port runs a timer equal to the hello timer plus one second.¹² The timer starts when the port emits a notification. Until it expires, the port sets the TC bit to 1 in every BPDU it sends. You can also see some periodic BPDUs without the TC bit: they originate from a port that only received a notification and therefore did not arm its timer.

Security

RSTP is weak against configuration errors and malicious actors. A bridge not talking RSTP can create a loop. An attacker can insert themselves into the topology to disrupt the service, spy on the traffic, or alter it.

To mitigate such problems, you need to identify the edge ports. An edge port connects to an end device, like a PC or a printer. Such devices do not generate BPDUs and cannot create a loop. RSTP defines two related flags:

• When true, AdminEdge initializes a port as an edge port. It defaults to false.
• When true, AutoEdge lets a port become an edge port when it does not receive BPDUs for 3 seconds. It defaults to true.

If an edge port receives a BPDU, regardless of the values of these two flags, it reverts to a non-edge port.

R0 @1.5,1.5 prio=8192

# AutoEdge=true, AdminEdge=false, bridge
S1 @3,1.58
R0 -- S1

# AutoEdge=true, AdminEdge=false, end device
H1 @2.84,2.18 icon=🖨️ proto=none
R0 -- H1

# AutoEdge=true, AdminEdge=true, bridge
S2 @2.18,2.84
R0 -- S2 R0:edge

# AutoEdge=true, AdminEdge=true, end device
H2 @1.58,3 icon=💻 proto=none
R0 -- H2 R0:edge

# AutoEdge=false, AdminEdge=true, bridge
S3 @0.68,2.76
R0 -- S3 R0:edge R0:no-auto-edge

# AutoEdge=false, AdminEdge=true, end device
H3 @0.24,2.32 icon=📠 proto=none
R0 -- H3 R0:edge R0:no-auto-edge

# AutoEdge=false, AdminEdge=false, bridge
S4 @0,1.42
R0 -- S4 R0:no-auto-edge

# AutoEdge=false, AdminEdge=false, end device
H4 @0.16,0.82 icon=📺 proto=none
R0 -- H4 R0:no-auto-edge

# Network port, bridge
S5 @0.82,0.16
R0 -- S5 R0:network S5:network

# Network port, end device
H5 @1.42,0 icon=☕ proto=none
R0 -- H5 R0:network

# AdminEdge=true, bpdu-guard=true, bridge
S6 @2.32,0.24
R0 -- S6 R0:bpdu-guard R0:edge

# AdminEdge=true, bpdu-guard=true, end device
H6 @2.76,0.68 icon=💡 proto=none
R0 -- H6 R0:bpdu-guard R0:edge

In the topology above, S1, S2, S3, S4, S5, and S6 act as bridges, while H1, H2, H3, H4, H5, and H6 act as end devices:

• S1 and H1 are on a port without a specific configuration: AutoEdge is true, AdminEdge is false,
• S2 and H2 are on a port where AdminEdge is true,
• S3 and H3 are on a port where AutoEdge is false and AdminEdge is true,
• S4 and H4 are on a port where AutoEdge is false.

If you start the topology and wait about 20 seconds, links to S1, S2, S3, S4, H1, H2, H3, and H4 eventually forward user traffic: none of the flags matter.

But what about the two remaining pairs? S5 and H5 connect to a network port. Such a port enables a non-standard feature: bridge assurance. The port transmits BPDUs regardless of its role. If it does not receive BPDUs for 3 consecutive hello periods, it transitions to the discarding state. On the link between R0 and S5, you can see BPDUs traveling in both directions, unlike the other links, where only designated ports send BPDUs.

S6 and H6 connect to a port where AdminEdge is true and BPDU guard is enabled. This is another non-standard feature that shuts down a port if it receives a BPDU.

In summary, if you expect a port to be an edge port, you should set AdminEdge to true and enable BPDU guard. Otherwise, declare it as a network port.

Why RSTP today?

A compelling use case for RSTP today is an out-of-band network for a datacenter, since you can tolerate an outage of a few seconds. The configuration is minimal and you can use cheap switches, like a Cisco 2960X.¹³ You need two switches acting as root bridges, and you build several loops to connect OOB switches in each cabinet. This simple design survives one failure on each loop.¹⁴

:protocol rstp
:tx-hold 10

# Root bridges
R1 @0,1 prio=0
R2 @0,2 prio=4096
R1 -- R2 cost=200 R1:network R2:network
R1 -- R2 cost=200 R1:network R2:network

# First loop
C1  @1,0 icon=🗄️
C4  @2,0 icon=🗄️
C7  @3,0 icon=🗄️
C10 @4,0 icon=🗄️
C12 @5,0 icon=🗄️
C13 @5,3 icon=🗄️
C15 @4,3 icon=🗄️
C18 @3,3 icon=🗄️
C21 @2,3 icon=🗄️
C24 @1,3 icon=🗄️
R1  -- C1  R1:network C1:network
C1  -- C4  C1:network C4:network
C4  -- C7  C4:network C7:network
C7  -- C10 C7:network C10:network
C10 -- C12 C10:network C12:network
C12 -- C13 C12:network C13:network
C13 -- C15 C13:network C15:network
C15 -- C18 C15:network C18:network
C18 -- C21 C18:network C21:network
C21 -- C24 C21:network C24:network
C24 -- R2  C24:network R2:network

# Second loop
C2  @1,0.5 icon=🗄️
C5  @2,0.5 icon=🗄️
C8  @3,0.5 icon=🗄️
C11 @4,0.5 icon=🗄️
C14 @4,2.5 icon=🗄️
C17 @3,2.5 icon=🗄️
C20 @2,2.5 icon=🗄️
C23 @1,2.5 icon=🗄️
R1  -- C2  R1:network C2:network
C2  -- C5  C2:network C5:network
C5  -- C8  C5:network C8:network
C8  -- C11 C8:network C11:network
C11 -- C14 C11:network C14:network
C14 -- C17 C14:network C17:network
C17 -- C20 C17:network C20:network
C20 -- C23 C20:network C23:network
C23 -- R2  C23:network R2:network

# Third loop
C3  @1,1 icon=🗄️
C6  @2,1 icon=🗄️
C9  @3,1 icon=🗄️
C16 @3,2 icon=🗄️
C19 @2,2 icon=🗄️
C22 @1,2 icon=🗄️
R1  -- C3  R1:network C3:network
C3  -- C6  C3:network C6:network
C6  -- C9  C6:network C9:network
C9  -- C16 C9:network C16:network
C16 -- C19 C16:network C19:network
C19 -- C22 C19:network C22:network
C22 -- R2  C22:network R2:network

This topology converges in about 6 seconds. Each loop should stay small (around 16 bridges) to reduce the probability of a double failure and to avoid sharing too much bandwidth. The design can evolve a bit without adding too much complexity: one VLAN per loop or one bridge domain per loop.

How large can a network be?

The maximum age, whose default value is 20, governs the maximum distance of a node from the root. The topology below is too big for BPDUs from R1 to reach beyond S20.¹⁵

:protocol rstp
:tx-hold 10
:max-age 20

R1 @0,0 prio=4096 icon=🌳
R2 @0,5 prio=4096 icon=🪾

S1  @1,0
S2  @2,0
S3  @3,0
S4  @4,0
S5  @5,0
S6  @6,0

S7  @6,1
S8  @5,1
S9  @4,1
S10 @3,1
S11 @2,1
S12 @1,1

S13 @1,2
S14 @2,2
S15 @3,2
S16 @4,2
S17 @5,2
S18 @6,2

S19 @6,3
S20 @5,3
S21 @4,3
S22 @3,3
S23 @2,3
S24 @1,3

S25 @1,4
S26 @2,4
S27 @3,4
S28 @4,4
S29 @5,4
S30 @6,4

S31 @6,5
S32 @5,5
S33 @4,5
S34 @3,5
S35 @2,5
S36 @1,5

R1  -- S1
S1  -- S2
S2  -- S3
S3  -- S4
S4  -- S5
S5  -- S6
S6  -- S7
S7  -- S8
S8  -- S9
S9  -- S10
S10 -- S11
S11 -- S12
S12 -- S13
S13 -- S14
S14 -- S15
S15 -- S16
S16 -- S17
S17 -- S18
S18 -- S19
S19 -- S20
S20 -- S21
S21 -- S22
S22 -- S23
S23 -- S24
S24 -- S25
S25 -- S26
S26 -- S27
S27 -- S28
S28 -- S29
S29 -- S30
S30 -- S31
S31 -- S32
S32 -- S33
S33 -- S34
S34 -- S35
S35 -- S36
S36 -- R2
R1  -- R2 cost=200 down

Once the topology settles, part of the network considers R1 the root, while the other votes for R2. At the boundary, S20 tries to start a synchronization with S21 to move its designated port to the forwarding state. The BPDU looks like this:

Spanning Tree Protocol
    Protocol Identifier: Spanning Tree Protocol (0x0000)
    Protocol Version Identifier: Rapid Spanning Tree (2)
    BPDU Type: Rapid/Multiple Spanning Tree (0x02)
    BPDU flags: 0x4e, Agreement, Port Role: Designated, Proposal
    Root Identifier: 4096.02:00:00:00:00:00
    Root Path Cost: 400000
    Bridge Identifier: 32768.02:00:00:00:00:15
    Port identifier: 0x8002
    Message Age: 20
    Max Age: 20

S21 rejects it because the message age equals the maximum age. On the other hand, the BPDU S21 sends to S20 looks like this:

Spanning Tree Protocol
    Protocol Identifier: Spanning Tree Protocol (0x0000)
    Protocol Version Identifier: Rapid Spanning Tree (2)
    BPDU Type: Rapid/Multiple Spanning Tree (0x02)
    BPDU flags: 0x7c, Agreement, Forwarding, Learning, Port Role: Designated
    Root Identifier: 4096.02:00:00:00:00:01
    Root Path Cost: 320000
    Bridge Identifier: 32768.02:00:00:00:00:16
    Port identifier: 0x8001
    Message Age: 16
    Max Age: 20

This is not enough to change S20's root port because S20 has a lower root identifier-4096.02:00:00:00:00:00 vs 4096.02:00:00:00:00:01.

Fixing the link between R1 and R2 resolves the issue. The maximum message age any packet carries is now 18, below the configured maximum age. But it only works until another link breaks. A plausible fix is to increase the maximum age to 40.¹⁶

How fast is RSTP?

RSTP usually converges in a couple of seconds at startup. It often repairs a tree in less than a second. Even the 38-bridge topology takes less than 10 seconds to converge.¹⁷ Some topologies can take a bit more time to recover when the root bridge becomes unavailable.¹⁸

:protocol rstp

R0 @1,0 prio=0
S1 @1,1 prio=4096
S2 @0,2 prio=8192
S3 @2,2

R0 -- S1
S1 -- S2
S2 -- S3
S3 -- S1

In the topology above, start the simulation, wait for convergence, hit stop, and cut the link between R0 and S1. The topology is already optimal, but RSTP has a hard time converging again.

First, S1 loses its root port. It has no more information about R0 and elects itself as the root bridge. It keeps its ports to S2 and S3 as designated ports in the forwarding state. Step once and it sends a BPDU to both S2 and S3 to let them know about the root change. When receiving it, S2 accepts S1 as its root because it does not have a better root on another port. It elects the port to S1 as its root port. The other port stays a designated port. Both ports keep forwarding.

When receiving the BPDU from S1, S3 behaves differently: it knows R0 as a better root than S1 through its alternate port to S2. It promotes this port to a root port and demotes the port facing S1 to a designated port, which requires a new agreement. Step once and S3 sends a proposal to S1 with R0 as the root bridge. S1 elects R0 as the root bridge and promotes its port to S3 as a root port.

During the same step, S3 also receives a BPDU from S2 stating that S1 is the root bridge. Therefore, S3 has no port left with R0 as the root bridge: it elects S1 as the root bridge and its port to S2 as the root port. Step once and its next BPDU to S1 includes this information: S1 elects itself again as the root bridge. But during the same wave, S1 sends a proposal to S2 with R0 as the root bridge. While S1 and S3 agree that S1 is the root bridge, S2 now believes this is R0! In turn, S2 again convinces S3 that R0 is the root bridge, S3 convinces S1, S1 convinces S2, and S2 convinces S3.

This could go on forever, but it does not. The BPDUs saying "R0 is root" eventually age out when the message age goes past the maximum age. In the example above, at the eleventh second, S2 sends a BPDU to S3 with R0 as root, but S3 drops it because its message age reached the maximum. With some luck, the topology can also converge faster if a port stops transmitting new BPDUs after tripping the transmit hold count, whose default value is 6 per second.

About MSTP

MSTP is the "VLAN-aware" version of RSTP: it runs several instances of RSTP and lets the administrator map each VLAN to a specific instance. For example, you can map VLANs 100 to 200 to a first instance, and 300 to 400 to a second instance. The remaining VLANs map to a special instance named the Internal Spanning Tree (IST). MSTP adds its own complexity, but the gist is that you have several logical topologies acting independently. If you want to dig deeper, have a look at "MSTP Tutorial Part I: Inside a Region."

About the interactive examples

The interactive examples run MSTPD directly in your browser, compiled to WebAssembly with emscripten. A C API replaces the code talking to the Linux kernel: it manages bridges and ports, exports state as JSON, and drives time deterministically. A JavaScript wrapper makes it more user-friendly:

import { loadMSTPD } from "./dist/mstpd.mjs";
const mstp = await loadMSTPD();

// Create 3 bridges
const a = mstp.createBridge("A", { priority: 4096 });
const b = mstp.createBridge("B", { priority: 8192 });
const c = mstp.createBridge("C");

// Each bridge has two ports
const a1 = a.addPort("a-b", { portno: 1 });
const a2 = a.addPort("a-c", { portno: 2 });
const b1 = b.addPort("b-a", { portno: 1 });
const b2 = b.addPort("b-c", { portno: 2 });
const c1 = c.addPort("c-a", { portno: 1 });
const c2 = c.addPort("c-b", { portno: 2 });

// Build a triangle topology
mstp.link(a1, b1);
mstp.link(a2, c1);
mstp.link(b2, c2);

// Enable all bridges and ports
for (const br of [a, b, c]) br.enable();
for (const p of [a1, a2, b1, b2, c1, c2]) p.enable();

// Execute 40 seconds' worth of wall clock and display the topology
mstp.step(40);
console.log("Topology:", mstp.topology());

Several dozen unit tests explore the features of MSTPD and check that they work correctly in this environment:

$ node --test *.test.mjs
✔ two bridges: lower priority becomes root (41.657342ms)
✔ triangle loop: exactly one port blocks and all agree on the root (5.832ms)
✔ breaking the active link reconverges and restoring recovers (18.730753ms)
[…]
ℹ tests 40
ℹ pass 40
ℹ fail 0
[…]
ℹ duration_ms 396.190897

Additional JavaScript code looks for specific <pre> blocks containing a topology definition and turns them into the interactive widget. You can inspect and modify the definition by hitting the "edit" button.

There is also a cool trick to tell whether the topology has converged. After each step, we save a snapshot of the simulation memory, play 50 seconds' worth of simulation to check if the topology is stable, and travel back in time by restoring that snapshot. 🕰️

The complete code lives on GitHub. I am happy with the result. It can be difficult to follow everything happening during a single step, but stepping forward and backward helps. I plan to use the same approach in future blog posts about networking features.

24 Aug 2026 3:00pm GMT

Imagine you rent office space for a three-day event. You quickly set up a few Ethernet switches and tape some cables on the floor to get everyone online. Unfortunately, Stan, your clumsiest coworker, kicks out a cable every time he gets up for coffee. Spare cables would fix that, but a loop turns into a broadcast storm: Ethernet packets multiply until nothing else gets through. That's where the spanning tree protocol comes in: it blocks just enough of the spare cables to leave a loop-free tree, and rebuilds it in a second each time Stan strikes again.

This content is also available as a text version, with interactive demos that run a real implementation directly in your browser!

This video is an experiment.¹ Honestly, except for Radia Perlman reading her poem,² you should read the original article instead. It presents the same content, but you can play with the interactive examples, which are the main contribution. On the other hand, if you happen to like the video, be sure to tell me in the comments!

24 Aug 2026 2:59pm GMT

Context

Recently I was trying to reproduce a bug with citeproc.el and org-mode in emacs.

I thought I could use package-vc-install to install a set of upstream emacs packages at fixed versions, and thereby let citeproc upstream test in the same environment as I have.

It turns out that getting emacs to load the non-builtin version of org via package-vc-install did not work because

• org-mode needs to run make after cloning
• once package.el was initialized, I always seemed to end up with the built in org-mode (yeah, I realize that isn't an explanation).

Recipe part 1: get org

Here you can replace 9.8.7 with any other tagged release

  EMACSHOME=$(mktemp -d)
  git clone https://git.sr.ht/~bzg/org-mode ${EMACSHOME}/org
  git -C ${EMACSHOME}/org reset --hard release_9.8.7 
  make -C ${EMACSHOME}/org autoloads
  emacs -Q --batch -L ${EMACSHOME}/org/lisp --eval "(progn (require 'org) (message (org-version)))"

This should print 9.8.7, not the version of built in org-mode.

Recipe part 2: add-on packages

Now to test some add-on packages, run

    emacs -Q --init-directory ${EMACSHOME} -L ${EMACSHOME}/org/lisp

  (progn
    (require 'org)
    (package-initialize)
    (package-vc-install "https://github.com/emacs-straight/queue")
    (package-vc-install "https://github.com/joostkremers/parsebib" "6.7")
    (package-vc-install "https://github.com/rejeep/f.el" "0.21.0")
    (package-vc-install "https://github.com/magnars/s.el" "1.13.0")
    (package-vc-install "https://github.com/akicho8/string-inflection" "1.0.16")
    (package-vc-install "https://github.com/andras-simonyi/citeproc-el" "0.9.5"))

You can then run your tests in that emacs right away, or restart the environment with

  emacs -Q --init-directory ${EMACSHOME} -L ${EMACSHOME}/org/lisp

24 Aug 2026 10:30am GMT

I haven't made a new book haul post in I don't know how long, so a lot of books have piled up and many have already been reviewed. Here's the overdue catch-up in case anyone is curious what books I am finding interesting before the reviews get posted.

Ilona Andrews - Magic Bites (sff)
Elizabeth Bear - In the House of Aryaman, a Lonely Signal Burns (sff)
Oliver Burkeman - Four Thousand Weeks (non-fiction)
Miles Cameron - Whalesong (sff)
Lee Child - Killing Floor (thriller)
august clarke - The Felicity Complex (sff)
Alison Cochrun - Here We Go Again (romance)
Dan Davies - The Unaccountability Machine (non-fiction)
Linzi Day - Midlife in Gretna Green (sff)
Linzi Day - Painting the Blues in Gretna Green (sff)
Linzi Day - Ties that Bond in Gretna Green (sff)
Linzi Day - Spilling the Tea in Gretna Green (sff)
Michelle Diener - Dark Ambitions (sff)
Michelle Diener - Dark Class (sff)
Michelle Diener - Collision Course (sff)
Michelle Diener - Crash Course (sff)
Henry Farrell - Underground Empire (non-fiction)
Kathleen A. Flynn - The Jane Austen Project (sff)
Victoria Goddard - The Hands of the Emperor (sff)
James Herriot - All Creatures Great and Small (mainstream)
James Herriot - All Things Bright and Beautiful (mainstream)
James Herriot - All Things Wise and Wonderful (mainstream)
James Herriot - The Lord God Made Them All (mainstream)
James Herriot - Every Living Thing (mainstream)
Lauren Hough - Monster of a Land (non-fiction collection)
Bethany Jacobs - This Brutal Moon (sff)
Guy Gavriel Kay - Written on the Dark (sff)
Mary Robinette Kowal - The Martian Contingency (sff)
Ann Leckie - Radiant Star (sff)
C.B. Lee - Coffeeshop in an Alternate Universe (sff)
Fonda Lee - The Last Contract of Isako (sff)
Julie Leong - The Teller of Small Fortunes (sff)
Julie Leong - The Keeper of Magical Things (sff)
R.Z. Nicolet - The Cloak and Its Wizard (sff)
Claire North - Slow Gods (sff)
Rebecca Ore - Writing's Writing (non-fiction collection)
Suzanne Palmer - Ode to the Half-Broken (sff)
Gareth L. Powell - Fleet of Knives (sff)
Cameron Reed - What We Are Seeking (sff)
Beth Revis - Full Speed to a Crash landing (sff)
Beth Revis - How to Steal a Galaxy (sff)
Beth Revis - Last Chance to Save the World (sff)
Natalie Zina Walschots - Villain (sff)
Jo Walton - Everybody's Perfect (sff)
Martha Wells - Platform Decay (sff)
James White - The Galactic Gourmet (sff)
James White - Final Diagnosis (sff)

The James Herriot books were ones my parents were getting rid of. I have them marked as mainstream fiction as a short-hand since "fictionalized autobiography" seemed like too much of a mouthful.

23 Aug 2026 9:29pm GMT

Two Debian Days in one week

The Debian Project was officially founded by Ian Murdock on August 16, 1993. The Debian community celebrates its birthday, Debian Day, on or around this date every year. This year, I had the chance to attend two of them: one in João Pessoa, Paraíba, and another in Brasília, the capital of Brazil.

João Pessoa

In João Pessoa, we had a two-day event. The first day was dedicated entirely to workshops, and I ran a packaging workshop for newcomers.

It was the first time I had been responsible for a workshop, and it was a great experience. We didn't have a lot of time, so I decided to start with a 30-minute talk explaining a few things about Debian. For example, I made this image to explain the packaging workflow:

This image was based on The Debian Administrator's Handbook, and I think the participants really enjoyed learning about this workflow. When I showed the slide with this image, it was the moment when I received the most questions.

After the talk, I explained my way of working and what they were going to do. The hardest part was setting up the environment, since my approach uses sbuild + gbp. They were running different Debian releases and, because of my inexperience with workshops, I had some of them configure sbuild with unshare, even though it is only available in stable through backports.

Some of them even managed to learn how to use backports, while others decided to start again using the "old" way.

One thing that helped a lot was the Debian Brasil Wiki. It has all the instructions for configuring sbuild in Portuguese, along with great examples. The Brazilian wiki is an opinionated version of the Debian Wiki. We generally prefer to use it for the convenience of having the exact workflow we follow, as well as an up-to-date Portuguese version of our process.

If you want to learn more about the Brazilian community, you can find more details in the schedules from previous DebConfs. We almost always had a talk about the community and its activities.

In the end, everyone successfully set up their development environment, and all six participants made their first contribution to Debian. If you take a look at my upload tracking page, you will see that every upload made on August 15, 2026 was a sponsored upload from this event. One of them appear twice in the list because I sponsored the upload and also made some other changes.

I also asked all of them to put this in their changelog:

* My first contribution!

The idea was to make it clear to other people that they were only working on small Lintian issues as a way of learning and understanding the process. By the way, I made a UDD query to find packages with the following Lintian tag: redundant-rules-requires-root-no-field. To fix this issue, they only had to remove one line from the debian/control file.

It is obvious that these uploads are not particularly useful. I call them "motivational uploads" because my goal is to help newcomers understand the process and immediately give them the reward of having made a contribution to Debian.

I'll try to keep in touch with them. My plan is to hold another session, this time remotetly, to help them continue contributing to Debian. In fact, I already have another package prepared by one of them waiting for my review.

The second day was a full-day event featuring a bunch of talks from the local community. I gave a talk explaining the new members process.

I was the only Debian Developer at the event, and I think having a DD there made a real difference. Being there to answer questions, and simply being present, makes Debian feel more tangible and accessible to people.

A big shout-out to Rafael Rocha, who put in a lot of work to make this event happen, with the help of many volunteers who contributed along the way.

Brasília

One thing I really like about Debian Days is that each place has its own way of doing things. In João Pessoa, we had a MiniDebConf-like event, while in Brasília, we had something smaller but still very valuable. We decided to keep things simple: talk to a few students at the University of Brasília (UnB) and then go somewhere to eat and have a few drinks.

A bit of history

For those who don't know, the DebConf 19 was held in Curitiba, Brazil. After the event, Arthur Diniz got really excited about Debian and decided to go back to his University, UnB, to share his experience and encourage more people to contribute to Debian.

I attended one of his talks, thanks to Joenio Costa, who invited Arthur to give the talk. Joenio was also my professor at the time and a Debian contributor. I really liked what Arthur had to say about free software, and he did a great job of presenting the Debian community as a friendly and welcoming place.

So I decided to attend local meetings of the Debian Brasília community, which had been inactive for a long time. Lucas Kanashiro was the Debian Developer who answered our questions and, as I mentioned earlier, simply being there made Debian feel more tangible.

Everything stopped when the pandemic began. Then, towards the end of 2020, I saw a message in the Debian Brasília channel saying that the meetings were back, this time remotely. I was hesitant to join because, back in 2019, I hadn't managed to make a packaging contribution, even with their help. I had eventually given up on the process. So this time, I decided to join the meeting with something already prepared for review. I watched all of Eriberto's packaging videos, picked a random package, and joined the meeting.

I remember Kanashiro being excited that someone had just shown up with something ready for review. At the time, it was only the second meeting since Debian Brasília had come back online, and none of the newcomers had started working on contributions yet.

During the same meeting, he also convinced us, the newcomers, to give a talk about Debian just three days later.

The MiniDebConf Online Brazil 2020 was happening on Sunday, and the meeting was on the Thursday before it. Since he has great convincing skills, I went along with the idea and prepared the talk with Francisco Ferreira.

That was the rebirth of the Debian Brasília community.

Since then, we have maintained a close connection with the University of Brasília, and today, at least seven Debian Developers are from UnB, whether as former students or former professors.

The reason I told this story is that, even though the Debian Day we held in Brasília was smaller, it is part of something that has been working for us for several years: staying close to an University. We've managed to attract and retain many people who share the same values and interests.

I've hope you all had a great Debian Day. If you're reading this and aren't part of the Debian community but would like to join, get in touch!

23 Aug 2026 6:22pm GMT

In an option review I did in 2024, shortly after the xz-utils backdoor, I explained that having GSS-API authentication and key exchange support in the main OpenSSH packages is problematic. The key exchange patch is large and intrusive. Furthermore, even linking to the necessary libraries is not without risk: as the Ebury malware attack demonstrated way back in 2009, each extra library linked into security-critical daemons such as sshd (or nowadays into its privilege-separated helper programs) can modify the behaviour of the daemon even if you aren't doing anything that would involve calling into that library. Of course some of that risk remains, but as Damien Miller wrote, minimizing the number of libraries that end up in the address space of sshd and friends is still valuable.

I just uploaded openssh 1:10.4p1-5 to unstable, completing this split. As of this version, the OpenSSH client and server are built without GSS-API authentication and key exchange support. If you need those features, install openssh-client-gssapi or openssh-server-gssapi instead, as appropriate. Debian 13 (trixie) already has packages with those names that just depend on the regular openssh-client and openssh-server so that you can pre-emptively install them, as documented in the release notes.

The new openssh-*-gssapi packages have relatively tight dependencies on openssh-common, in order for the testing migration system to ensure that we can't forget to keep them up to date. This will mean a bit more ongoing work for me on each new upstream version, but I think it will be manageable.

23 Aug 2026 5:16pm GMT

Disclaimers

The current discussion in Debian aroun the AI GR is very heated, and I won't add to that, however, I am very confused about some of the viewpoints there. But, I had no idea how to even try to write this, so did shut up, until I saw Aigars' excellent Optimistic take on AI, which motivated me to try, at least. For the record, I fully subscribe to the post, and to the voting suggestions (and I just voted).

Also, for full disclosure, I don't think I did any contribution to Debian until now using AI, neither packaging, nor emails, nor bug reports. And this blog post specifically is 100% hand written.

With that out of the way… there are two points I want to make in this post.

AI is useful, even if it has risks

First is, that even if we could put the genie back in the metaphorical bottle, we should not. We do need to continue working towards safe AI, and efficient AI (less environmental impact), but we should not work towards removing the usage of AI. There are already significant advancements in sciences and technology thanks to the use of AI, so desiring AI to not exist (assuming we had a magical wand) is the wrong approach.

Sure, AI has significant risks - and I can see ways in which AI can do significant damage to society - but I don't think we can go from Kardashev I to II without the use of AI, and definitely not to III. And I think, that should be the goal.

A few simple examples: Do we want to rollback all the 20 years old security issues that AI found? Do we want to rollback the recent Moderna cancer findings? Do we want to rollback the concept of "extremely large scalle pattern matchings", just because it runs on chips and no longer in one person's head?

Reading Debian lists

The second point is, lately I found less and less enjoyment in reading Debian lists. Even with that already being the case, I feel soo disconnected from many of the opinions being voiced in this discussion.

On one hand, it's normal and healthy that people have different opinions, disagree, and move foward.

On the other hand, looking at one of the proposed options:

• "Moderators and disciplinary teams may make narrow and tailored exceptions to rule 4, and decide on interpretation".
• "Violations of these requirements should be treated as violations of the relevant Code of Conduct and should result in swift and proportionate disciplinary action".

I already knew Debian, and some large parts of the OSS world, is left leaning. But those phrasings, to me, are too close to socialism/communmism. As someone who grew up under communism, this is a much more slippery slope (disciplinary teams? really?) than AI usage. Ask me in person for more details.

So, it is possible that Debian continues to evolve in such a way that I don't find myself in any way close to its ongoing culture. I will be sad at that point, but it will be what it is.

Where to?

I think that, until such a time that an AI bubble bursts, what any organisation should do is try to logically see where and if AI can help. And in an organisation that is about computer software, I see hundreds of places that are subject to very large scale pattern matching… so the half of the discussion is, to me, mind-boggling.

To be clear, it's not about "if you can't beat them, join them". As I wrote above, I think AI is useful, so the point is how to use it effectively.

Well, will see what Debian votes. I am half curious, half sad alreay.

23 Aug 2026 4:19pm GMT

Programming language generations

When I was young, I learned about a model of classifying programming language: the system of programming language generations.

In this model, first generation programming languages are, basically, where you program the computer in the language that is defined by its architecture. On a Von Neumann machine, with its load-and-store architecture, you do that by inputting a string of numbers. The first programmer in human history -- her name was Ada Lovelace -- wrote in a first-generation language. 1GLs aren't so much invented as they are a byproduct of the computers for which they're created.

Second-generation languages are the assembler languages. Because humans are not computers, and because decoding long lines of numbers to understand what the computer is doing, when programming became a full-time job, the programmers that did it decided that doing all this assembling manually is too complicated, so they quickly wrote assemblers to automate the process for them. They still could understand the 1GL output of the 2GL assembler, but most of them quickly forgot how to write software in a first-generation language. Not that anyone cared, as the translation from a 2GL to a 1GL is lossless and you can just revert it.

Third-generation languages are higher-level languages. When the first 3GLs were invented (such as COBOL and, more famously, FORTRAN) in the late 1950s and early 1960s, it was believed by some that the work of programming a computer so accessible to non-programmers that the job of programmer would eventually cease to exist, and people would just ask the computer what they needed by entering COBOL instructions. This of course was ridiculous and incorrect, because converting algorithms to computer instructions, whether at the 2GL or 3GL level, is a specialized skill that some automation can perhaps make simpler but never completely take away the need for. At the time, some people also felt to some extent that using 3GL wasn't the same thing as actually programming 3GLs, but eventually the world moved on and embraced things. The invention of 3GL environments reduced, but did not completely take away, the need for people to understand 2GLs, as compiler and operating system authors still need to understand them, and some highly optimized code still continues to be written in 2GLs to this day.

Fourth-generation languages abstract away some or all of the process of programming. For instance, a database-related 4GL will hide away the complexities of storing data in particular locations, how to fetch that data, how to index it such that you can fetch it efficiently, how to loop over the data to get you a summary of that data, and instead allows you to express the required information in an abstract way, expecing the computer to fill in the blanks. When SQL, an early 4GL, was invented, some people believed that the language made accessing databases so simple that the requirement to implement database applications would eventually cease to exist and we would just hand SQL prompts to users who need to access data. This of course was ridiculous and incorrect, because understanding data schemas and using that understanding to query data from a database is a specialized skill that perhaps a higher abstraction can help you make simpler, but that in the longer run it can never completely take away the need for. The invention of 4GLs also reduced, but did not completely take away, the need for people to understand how to do the things that the 4GLs automate for you manually, as the people who do write those things still need to understand them, and there are also environments where these particular 4GLs are rather not appropriate or just very slow.

The first definition of programming language generations that I read about in the 1980s simply stated that fifth-generation languages did not yet exist, but that they would in the future, and that in those, you would "tell the computer what to do, and it would then do that". Now that we have a way of doing so, it could be said that by some definition, we now actually do have a number of 5GLs. The existence of these LLM systems has caused some, especially the people who build and exploit these systems, to exclaim that programming as we know it today is going to cease to exist, and everyone will just ask an LLM to generate a program, which will then do so. That is of course ridiculous and incorrect, as no automaton can generate software from nothing; input is still required for the model to be able to produce something that approaches usability, and being able to word that input in a correct and productive fashion will be a skill that future programmers can benefit from. I ran some experiments a while back, and from that concluded that, if we look only at the technical side, LLM use can, in some niches, increase productivity for a programmer. There are certainly things that you shouldn't use an LLM for, but equally there can be cases where use of an LLM to perform some task that traditionally would have been done by a programmer would be a net positive.

But LLMs, as they exist today, are highly problematic.

They require vast amounts of data to build the model. The companies that build these models are disrespectful of people who run web services, and as a result, everyone now has to implement various types of application firewalls just to not make systems fall over from the overwhelming requests for data. They are also disregarding the licenses that are attached to these vast amounts of data, which makes me, as a person who believes in the tenets of free software, sad.

They require vast amounts of energy, causing an already-critical global warming crisis to, well, not improve.

They require vast amounts of coolant to dissipate the energy concentrated in their data centers, causing further environmental effects.

In this, they are problematic and to be avoided. But these are side states of the current state of affairs; I do not believe that they are inherently implied to be able to build and operate an LLM -- any LLM.

I guess it's fair to say that my feelings towards LLM usage are complex and many-faceted. I haven't been involved in many debates about the subject, debates that to me seem to be mostly focused on "LLM good" vs "LLM bad" arguments that aren't as nuanced as the position that I would believe is more accurate. This is not because I don't care, but partially because I've been busy in my personal life recently and partially because the whole thing seems somewhat disheartening.

But then Debian popped up GR 2026-002, meaning, I now have to come up with an opinion about various candidate statements in the context of the above, which is... not easy. But I did it anyway.

There are 8 choices on the ballot, and they all have some truth and some falsehood to them. My position about LLMs can be summarized as:

• The current state of affairs wrt LLMs is disastrous and we should not encourage them
• However, there's no technical reason why this must remain true for all time
• And so any statement should keep in mind what might happen in the future and that the current disastrousness of the whole thing isn't guaranteed to continue to exist for all eternity.

With that, let's go over them.

GR vote options

Proposal A

Its summary, from the GR text:

This proposal aims to expressly forbid any contributions to Debian written with the use or assistance of large language models (LLMs) or other generative AI tools.

This falls squarely in the "LLM bad" camp, outlawing all generative-AI contributions, disregarding potential future ones where the problematic situations that exist today are not present.

It makes a change to the social contract, which is especially difficult to reverse (on purpose), and which therefore also will require a 3:1 supermajority, but if we want to ban LLM-assisted contributions, this is probably the best way to do it.

Proposal B

This one tries to allow AI-assisted contributions under certain conditions. It's mostly an "LLM good" proposal, with some caveats that can be discribed as "make sure you know what you're doing".

Proposal C

This proposal is both a weaker (in some places) and stronger (in other places) version of Proposal A. It makes changes to the code of conduct instead of to the social contract, and it also wants to, at least, suggest policy to parties beyond the Debian project. By not changing the social contract, however, it is more likely to reach its simple majority requirement than proposal A.

I don't think the language that it wants to add to the code of conduct is particularly well phrased, however.

Proposal D

This is a weaker form of proposal B. The language is more compact and there are a few requirements that are spelled out in proposal B that are not spelled out in proposal D, but if you read between the lines you'll see that the requirement is still there really and I don't understand why proposals B and D were not merged into one.

Proposal E

This proposal tries to hold a middle ground between "LLM good" and "LLM bad". It appreciates that things are quite muddled at the present time, and that perhaps the situation might might change in the future. It acknowledges that certain questions remain unanswered and that perhaps future considerations might therefore be different. But it essentially refuses to take a stance on whether LLMs should be accepted by the project or not.

Proposal F

Similar to proposal E, this proposal tries to discourage Debian contributors from using LLMs, while still allowing people to use it should they want to, but with some requests and requirements to mark LLM-assisted contributions to account for those people who don't want to interact with LLM-generated software. As such, it is a proposal similar to proposal E that leans closer to the "LLM bad" camp.

Proposal G

This proposal aims to ensure that contributions directly to Debian are created by humans, while at the same time avoiding restrictions on the tools those humans may choose to use when contributing

Another "LLM bad" proposal, it however restricts the "bad" bits to only the direct output of the LLM. If you use an LLM to do something and then clean-room re-implement the same thing yourself, that's apparently fine.

Proposal H

This proposal condemns the use of LLM for its environmental and moral problems, but explicitly not for its technical considerations. I feel that it is closest to my position as explained above.

Voting

Expressing a vote on a ballot so convoluted and complicated like this one takes time. I have to read and understand every ballot option, and formulate an order of them.

And I shouldn't just state which option has my preference; Debian's voting process allows a rich expression of opinion on ballot options.

Anyway, I eventually ended up voting in a way that I think is consistent with my opinion. But it wasn't easy.

23 Aug 2026 2:02pm GMT

As I am writing this, there is a vote ongoing in the Debian project on how to deal with AI in general and AI-assisted contributions to Debian specifically. Massive discussions have happened in debian-vote and other locations. I have also asked questions there and offered my perspective. IMHO now is the time to summarize that, after all the discussions that I've had with people on multiple sides of this debate both online and offline, and explain how I will be voting and why. Hopefully that will be helpful to someone else as well. None of this has been compiled with AI assistance, but only because I think that forming opinions is not something where AI can really be helpful. Spellcheck was used though.

So, first I will describe how I see each of the 8 proposals, then what my vote will be, and then a bit more detail on the reasoning and thinking behind this. WARNING - this went long.

• Proposal A(1) - Action: ban all AI-assisted contributions via Social Contract amendment, except from upstreams (so not rolling back the Linux kernel and other software to "pure", pre-AI state). Claims that copyright/licensing status is unclear, quality is bad, community is being destroyed, web resources see extra load and that training consumes "staggering" resources. Needs 2/3rd majority to pass. - IMHO worst and most inconsistent. If copyright and licensing of AI products is unclear, then be consistent - ban ALL software with AI contributions, fork Linux kernel and other software from pre-AI versions, reject all security fixes of issues found with AI. Quality section lists problems that have not existed in the real world since at least a year of rapid AI coding development. Community section assumes that now all Debian contributions will be drive-by AI slop and no one will learn anything anymore. Ethics section mixes up effects of badly configured systems (AI web load is no different from load from a badly configured Perl script) with claimed "resource" usage without any context, taking on trust project ambitions of startups and assuming exponential growth. And then concludes that delivering less is in the interest of our users somehow.

• Proposal B(2) - Action: allow AI-assisted contributions, with conditions of: legality, accountability, disclosure, no uncoordinated bulk actions, privacy. Concerns on quality and legal status as well as environmental impact and scraper load are noted, but not really addressed beyond labelling them as concerns. - IMHO it is an ok starting position as it establishes that each contributing person must still be fully responsible for their contribution (both legally and technically) and for that has to also understand (and review) what they submit. Disclosure lets others know to watch out for other classes of problems when code was changed with AI assistance. Prior discussion for bulk changes just says that the (already established) practice should not be neglected just because now large changes are easier to do. And the privacy part warns against accidentally sending private or confidential data (like a not yet published security bug) to a public service where it could become public. Personally I would have liked a stronger statement to encourage use of environmentally responsible AI services and local AI tools. Possibly a preference for open-weight models with a clear path forward to preferring truly free AI models, when such a category of products could be clearly delineated and established.

• Proposal C(3) - Action: reject AI-assisted contributions at Code of Conduct level. Claims all the world's evils come from LLMs and that "Ethical and safe use of this technology is almost impossible". Goes as far as banning any use of LLMs even in Debian mailing list emails and Debian Planet blog posts - if you do, it's a CoC violation and may result in exclusion from the project. Additionally mandates the disclosure of the usage ... presumably to ban you more efficiently for it. - IMHO truly a dictatorial nightmare option. Zero actual reasoning or basis for such a decision. Zero sources. Nothing claimed in this option's rationale is even close to reality and nothing claimed there is in any way related to the actual technology being discussed. Like, an "LLM" does not automagically commit "fraud" when you use it, like this proposal claims, as if that was a well-known fact. LLMs are not all "owned by horrible people and companies". Even if some include a (prominent Debian user, long-time supporter and sponsor) Google into "horrible companies" (which is what this proposal implies!), there are plenty of LLMs owned by all kinds of companies all over the world and there are plenty of open-weight LLMs that are not really owned by anyone. Most invasive and dishonest option on the ballot.

• Proposal D(4) - Action: allow AI-assisted contributions, with conditions of: legality, accountability, disclosure, privacy. IMHO same as B, just shorter. Adds a "we don't recommend" towards others developing software with AI assistance. Seems pretty weird to add that and then immediately accept Debian contributors doing so. Assumes that the bulk change bit of B is implied as AI is just tooling, so bulk changes should be pre-discussed just like today - so no change and thus no point in mentioning that. Fair. D is a bit more explicit on expected technical details - like that the "person" submitting the change is supposed to sign it, not AI. Notable is the complete absence of resource usage or the environment from concerns. IMHO it would be better to have that and also recommendations on how to avoid causing environmental damage when using AI.

• Proposal E(5) - Action: no action as such - AI-assisted contributions must follow the same rules as all other contributions and those rules are sufficient. IMHO despite its length this is a very well-worded position statement that describes how and why AI-assisted contributions already work perfectly fine in the Debian context when all the same rules that apply to all contributions are also consistently applied to AI-assisted contributions. It describes how the same legality, accountability, no bulk change and privacy requirements are already in place and still apply and how AI-assisted contributions can and must still satisfy them. I could add again that some guidance would be nice here for both legal and environmental decisions when using AI, but in this case it does not really belong in this proposal itself. We as Debian do not have a document that requires that our non-AI-assisted contributions be made with only sustainably sourced electricity, for example. So why should AI be special one way or another? IMHO Debian should have a datacenter sustainability policy, regardless of the AI discussion.

• Proposal F(6) - Action: discourage AI, but allow it based on existing processes (similar idea to E). Dances a bit around the question of disclosure of AI use (as a courtesy) and accepting that some people may still ban all contributions where any AI was involved in any way. Which in turn discourages disclosure to avoid pointless rejection of valuable contributions (like security patches). IMHO this option is ok, but so watered down that it is bound to bring up further discussions and conflicts on details.

• Proposal G(7) - Action: ban non-humans from directly contributing to Debian. IMHO - another bizarre and self-contradictory option. It bans all Debian interactions with AI assistance, including email messages to Debian mailing lists and (supposedly) blog posts on Planet Debian. It "reminds" people who "use such tools assistively" of the DFSG and Social Contract - isn't that a threat of a ban and expulsion similar to C? The proposal does take pains to delineate where a contribution comes from AI as output (bad) vs when you are assisted by AI in the process of exploring, researching or maybe even reviewing the code, but you actually type all the code yourself and use the AI just as a taskmaster with a whip (good). And just like A or C it completely ignores how this inherently evil and unstable AI-generated code becomes perfectly fine and good as soon as someone develops that outside of the Debian project. Even if the same person then packages it for Debian the next day. It is hypocritical, unsustainable and ignores the needs of our users. Just like C it also bans someone writing an email or bug report in their native language and using a modern translation tool or service (that uses LLMs nowadays for better grammatical clarity) to translate that to English before sending it to a Debian mailing list or BTS. Heavy-handed and invasive. And the only reasoning provided for this is some unnamed "concerns" of "extra work" being borne by "other people"? Kind of does not feel right to bear such draconian restrictions for some unspecified concerns.

• Proposal H(8) - Action: condemn usage, but not actually ban anything. And then it goes on to claim (without any evidence or elaboration) that LLM usage accelerates the destruction of "planet earth" (sic). IMHO this proposal is at the same time the loudest ("The planet is burning") and also the one that demands the least action. It dances a really twisty line between raising "significant" concerns in all areas and even claiming that use of LLMs destroys the planet, flies by explicit condemnation of LLM usage and then suddenly collapses with not condemning LLM users and swinging to lamentations that it is actually impossible to impose policies on LLM usage or even detect when an LLM was used (which kind of directly contradicts bad quality claims from A, C and G) and lands on "encouraging" contributors not to use LLMs (where practical) and otherwise do nothing else. It's like this is a 5th draft that started off with the rationale and total ban like in C, but then got defanged so far that its action side no longer matches the rationale stated.

With all the above considered I will vote like this (earlier options are preferred over later options):

• Proposal E(5) - solid hack of integrating AI into already existing Debian rules and conventions
• Proposal B(2) - explicit and detailed
• Proposal D(4) - lower because of discouragement to others on what we agreed to do ourselves
• Proposal F(6) - I am not a fan of dancing around with disclosures
• Further discussion(9) - I do not want any option below this to succeed as they would do more harm than good
• Proposal H(8) - loud, but not doing anything actually
• Proposal A(1) - at least this one does not set rules for emails
• Proposal G(7) - at least this one allows an AI overseer to tell you what to write with your own fingers
• Proposal C(3) - the most draconic and invasive one that explicitly wants to kick people out of the project

Details on rationale

Hypocrisy - I find any proposal that would ban AI-assisted contributions to Debian, but at the same time not ban including AI-assisted contributions from upstream projects to be inherently hypocritical. If LLMs and AI are the very incarnation of evil (a puppy-killing machine, as the analogy went in some emails), then any rational proposal would involve excluding any and ALL code contaminated by this evil from the project. What does it matter if puppies were killed in writing the debian subfolder of the source code or the src subfolder? No proposals went there because everyone knows that such a ban would be the death of the relevance of the project for the future. Debian would be frozen on some old version of the Linux kernel forever and other software would be falling to the same problem too, for example as projects on GitHub start enabling AI-supported reviews with patch suggestions. Soon the "development" of Debian could just be stopped as there is nothing to develop without any upstreams.

Assumptions - a lot of proposals mention various "concerns" with at most one word, like "practical" or "community" without an explanation of what exactly they mean by that. The proposers assumed that everyone lives in the same info bubble as they do and already know everything that they mean and already agree to that. That is false. Proposal A was a positive stand-out in this area. Debian has contributors all over the world with very different exposure to different information sources and very different world views. If you want to convince the project as a whole that LLMs are bad because of "ethics", then you do really need to explain what you mean by that and give links to sources, at least as well as Proposal A did. All other proposals were really weak in this area.

Copyright - the question on how copyright law interacts with training LLMs and their outputs is still not settled law. The closest legal statements we have so far are that - just because an LLM is trained on copyrighted material does not make that LLM itself be a derivative work of the training data (you, however, cannot just create and distribute a "library" of copyrighted materials just because you plan to train LLMs on it). The output of the LLM might not be subject to copyright law at all, like a photo taken by a monkey. It would then be public domain and thus can be modified and then licensed by the user of the LLM. It might also be a derived work of the context of the inference (so for software - if you refactor a GPL project, the refactoring itself is likely GPL too). Any stricter interpretations would break a lot of existing copyright doctrine, such as raising questions like: "does the output of any programmer now become a derived work of the programming manual books they read in college?". In any case it is really not up to Debian to legislate the nuances of copyright law. And I strongly disagree with the concept that an author can tell me how I am allowed to use the learnings that I gained by reading their work. That is not how either copyright or society works. I can look at 10 pictures of a sunset and draw my own, inspired by the ones I saw. No one can forbid me that expression. The same must be true for a machine learning and replicating patterns.

Ethics - I've re-read all proposals and emails and the only real specifically ethical concern I could find was the complaint that some LLMs (or their training farms) are running their web scrapers too aggressively and that causes extra load on services. Like that is not an LLM problem. Scraping the web is not an inherent part of the LLM training or inference process. It's just a few misconfigured scripts. We saw the exact same thing in the early days of web search engine proliferation. Then we banned/blocked the misconfigured engines and the survivors learned that obeying robots.txt is one of the rules for surviving. Literally the exact same problem and it will be solved the same way. Did we ban all search engines back then just because some of them were misconfigured? No.

Some claims (like in Proposal C) are just bombastic hyperbole ("hazards to users' mental health", "fraud", ...) and on top of that have zero relevance to the topic at hand - AI-assisted contributions to Debian. What "hazard to users' mental health" is created when a Coderabbit spots that a lock is not taken before accessing a resource in a particular function and suggests an AI-generated patch to fix it? What "fraud" is committed by this? There is no sane answer. I get that some people are very busy fighting some culture wars and sometimes, some AI-bros happen to be on the other side of one such war, so it is useful to label everything coming from the AI sphere as "bad" in all possible and impossible ways. You do you. In private. Why pull Debian into that? Why force your position on everyone else in the project? Why deny everyone in the project access to useful tooling, just because you have strong feelings about some of the people promoting some of those tools?

This seems to me a repeating pattern here - blaming the technology as a whole or blaming all providers of this type of technology for failings (ethical or technical) of some of those providers. Like refusing to wear all shoes and condemning all shoemakers and sellers, just because some American billionaires figured out a way to make and sell cheap shoes by killing puppies. Not refusing and condemning those providers, but condemning all for the actions of a few.

Resource usage - this is a big topic for many and it has reasonable points to it. The LLM and AI technology has no inherent need to be damaging to the environment in any way for it to function. It does not need to burn oil or dig up cobalt. It does not need to sacrifice a ton of water to the Gods. It is perfectly possible to run AI (both inference and training) purely from green, electrical energy and cool data centers in equally sustainable ways, like with simple air-source heat pumps (also known as air conditioning) or even use it beneficially (many data centers are used for heating surrounding buildings via district heating). However, some AI companies do use non-green power for their data centers, some do use locally-limited fresh water for evaporative cooling (evaporated water still rains down as rain, it is not really lost, but that may happen in another location so lack of water can still happen locally). Some even run unlicensed natural gas turbines in their data centers to provide them with power. And those specific providers can and should be shunned and condemned. Not the other ones, who are doing the right things. Not the technology or its users or its outputs.

There is a very wide spectrum of options on how an AI system could be powered: starting from local execution on already existing private hardware powered by one's own local solar power (good), to a data center stuffed with borrowed AI-only cards powered by a gas turbine or coal power station that operates solely to supply this data center (bad). Proposals that talk about ecological impact, but do not even consider where on that (very wide) spectrum to draw the line between "good", "acceptable", "discouraged" and "bad" - well, I cannot see those proposals being actually serious about the environment to begin with. It feels like they just refer to it for points.

And if we go into the power question deeper, well the grid dynamics and economics become very, very complex and often also non-intuitive. Like, all large software companies with data centers (that also happen to provide AI services), like Google, Meta, Apple, Microsoft and others do actually care about sustainability (in part because their customers care and vote with their wallets) and so all of them use 100% green energy for their data centers (including AI data centers) .... "on an annual scale". Wait, what does that mean? Well, the electrical grid is special - the amount of electricity produced and consumed on the whole electrical grid together has to match almost exactly every second. If there is just a single second where there is significantly more energy consumed from the grid than is produced, the frequency will plummet and you get a brownout and risk a grid collapse. The same is true in reverse - that causes a voltage swell. So grid operators manage energy flows every second and command power stations to increase and decrease generation all the time. Some power stations are easier to regulate dynamically than others. In the end, all that means is that even if your data center has a contract for 100% green energy with your power company, at some seconds across the year there might not be enough green energy in the grid to fully supply ALL people and companies that have 100% green energy contracts. This gets compensated in other seconds, so that across the year ("on an annual scale") for each kWh that your data center pulled from the grid, the same amount of kWh of 100% green energy flows into the grid. But it might not happen at the exact same second. Pedantic companies, like Google, take that discrepancy and count that as CO2 emissions for themselves. And then they and the power companies (they have contracts with) invest billions into new green energy projects, better grids and better batteries so that eventually this discrepancy goes down to zero. In this way green AI data centers with their increasing consumption of green energy are actually doing a lot of good work in making our electrical grid more green. They are making more resources than they are consuming. And that is just the tip of the iceberg. This is a deep topic that really abhors generalizations like "more consumption = bad".

I've heard similar discussions in the context of electric cars - "so you got an electric car? you'd have fewer emissions if you drove no car at all!". That might be so. And I would also reduce my emissions to zero if I stopped breathing, but I really do not want that kind of thinking to be propagated further, especially when impressionable young people are around who may take it to its logical (but wrong!) conclusion. Instead I talk about how early adopters use electric cars to gather experience and achieve volume to start the network effects working. Once network effects of many electric cars on the roads are sufficient, it becomes an economically logical choice to get an electric car. People who cannot avoid having a car start to switch over. And at the point of mass switchover the reduction of emissions is so massive that those early adopters failing to go all the way to riding a bicycle becomes a rounding error.

But surely that does not apply to LLMs? They are only increasing consumption and bring no benefit?

Benefit - and here we have to actually talk about benefits. Because you cannot make any cost-benefit analysis if you do not actually fully investigate the benefits. Are there environmental benefits from running those AI models? Yes, in a lot of very diverse ways. Hard to measure, however. There are projects that are easy to quantify - like that Google AI project on contrail avoidance. An advanced, special model trained and executed in Google AI data centers was able to predict where in the air contrails would be produced and could generate proposed course adjustments to commercial flights to avoid specific heights in specific locations at specific times. This stopped these aircraft from creating contrails and those contrails did not make a further contribution to global warming. That benefit in a year was many times higher than the environmental cost of training and running that AI model. And it can keep running for many years accumulating further benefits.

On a personal scale, I've had problems that I bashed my head (and computer and CI resources) against without much success years ago solved with a few minutes of compute. Having a good enough candidate solution quickly is much cheaper from a resource perspective than spending days trying different things, running my PC for it, trying different patches on CI executions, doing different rebuilds. I've seen very significant benefits in AI-assisted development in enterprise environments where code way more complex than what is in Debian (especially in Debian tools and packaging) gets analysed, reviewed, modified or even refactored or rewritten in another language with AI assistance. And it generally works. The commonly mentioned "hallucinations" are a thing of last year in the coding context. Nowadays the AIs work in special coding harnesses and use real tools as foundational facts. You cannot "hallucinate" an API call or parameter if you have to run and pass the unit tests and integration tests by your harness before you can return "success" to the caller. I've personally seen high-level AI models read very complex software projects across multiple repositories and point out a very specific design consideration that was encoded in the code logic, but never mentioned in comments or documentation. It was so obscure that even I did not immediately know what it was talking about (and I wrote that code). Only on close inspection of code interaction across three repos did I remember that there was indeed that bug 2 years ago that I fixed by doing the change that this AI picked up (it wasn't in the history of this git repo due to repo migration). It mentioned this because it was very relevant to the task I initially gave it to review.

These LLMs in a proper harness with proper system instructions and usage approach are not just fancy spell checkers or auto-complete. They function more like very advanced pattern matchers. They have learned millions of patterns from training data. When they look at the code, they see hundreds or thousands of overlapping patterns. When you ask them to make or change something, they pull out a pattern (or ten) from their training and apply those patterns to the context of your program. You get something that looks just like the surrounding code, same style choices, same language, same comment voice, but it implements something new there, based on other patterns learned. If you've studied design patterns in your CS class, this will be familiar. But people can learn and remember maybe 20-30 patterns, while an LLM can have a million patterns and can combine them when needed. So it takes a pattern of Python code, pattern of standalone script, pattern of parsing command line parameters, pattern of classes, pattern for background threads, pattern for file tree traversing, pattern for pipes, ... and squishes them together to make a solution for your query. And then tries to debug it with compilation, tests and execution until it works as expected. Even if there is zero LLM development going forward, it will take many years to fully appreciate the benefits we can extract from the already trained models. They don't even have to be retrained - for existing languages they just keep working. For new language variations, like a new Python version, you can feed the changelog into context and they will be able to work with a Python version that they never saw in training. And patterns are mostly abstract, so not really specific to any language - human or programming.

This is another big enabler that LLMs have created that we have not really explored yet. LLMs have created really free software. People can actually create software that is perfectly suited just for them and no one else. They don't even have to know how to program and don't even need to speak English. I've seen people writing prompts in their native language and LLMs creating and then adjusting web apps or Android/iPhone apps and deploying them to the user's own phone. It was too buggy to work last year, but this year it is actually very functional for simpler use-cases. And the code looks just fine too - I've seen external contractors in a business setting deliver far worse. If you start with a good initial system prompt, the project will have architecture documentation, use-case documentation, unit tests, integration tests, deployment harness, testing and production deployments, audit logs, monitoring, clear git commits, CI validation on commit, ... Modern AI systems have the capabilty to deliver software freedom to people who are not coders. I really can not overstate the consequences this may have on the world.

Community - I find the concerns that new people will be using LLMs so much that they will no longer be understanding the actual code they are contributing a bit regressive. I don't see any significant difference between this and people relying on compilers, on high-level languages or on debhelper. Writing modern debhelper packaging feels more like writing configuration and not writing code. It takes really significant effort to dig down through layers of abstraction to find what actually is being executed in debian/rules. AI does not really make this worse. In fact, I find that AI can make it much easier to understand arcane syntax because you can ask an LLM to explain what is happening in any part of the code and it will do a pretty good job of it, digging down through the layers of abstraction for you. All the pro-AI proposals include the requirement that each human contributor needs to understand and stand behind their AI-assisted contribution and I believe that is a good requirement and also a sufficient requirement. Modern LLMs not only produce clear and concise code, but they are also capable of producing good comments explaining why the code is how it is, good commit messages explaining the change and reason behind it and also making corresponding changes to test suites and documentation. You know - the housekeeping stuff that is often skipped because it slows down the actual feature development, but then its lack becomes a problem for future contributors. Responsible use of AI assistance is a great chance to actually strengthen our community and make our software easier to maintain.

That said, I have no qualms about flat-out rejecting contributions that do not make sense. And it does not matter if they are made with or without AI assistance. If the contributor will not explain their patch, it might be they do not understand what their AI produced or it could be that the contribution is deliberately hiding a backdoor being planted. It is also quite common for a contribution of a new feature to be rejected because the author/maintainer does not believe that it is a good fit for the project. Featuritis is a real disease. AI or not. There have always been drive-by contributions to various projects. They will continue to exist. Each of them should be evaluated on its merits - is this feature valuable to our users and is the added complexity (if any) worth the functionality? A lot of security bug reports are "drive-by" contributions as well. And many of them nowadays are discovered, exploited and patched with AI assistance. We could reject them, but that just leaves us holding the bag on the now-known exploits.

And the New Maintainer process should be able to figure out if an upcoming Developer has actually understood the nuances of Debian packaging or not. A contributor with upload rights to the archive has to be able to create a basic package with no support tooling (maybe even without using debhelper?) and be able to understand and modify more complex packages (possibly with tooling support). IMHO that is a separate discussion that is worth having, involving experts from the educational sector.

Conclusion

IMHO the Debian project should not restrict what tooling individual contributors use to contribute. Expecting high-quality contributions and that contributors understand what they are contributing (as a first level of review) is enough.

However, Debian should provide its contributors (internal or external) with guidance on how to contribute in the best way possible. That could include:

• information on which AI services have Terms and Conditions that make them problematic for free software development, legally speaking
• information on which AI services do (or do not) achieve a sufficient level of sustainability to be worth recommending (and then do the same for other data centers we already use)
• information on which local AI models were trained in sustainable ways
• base-level prompts to set technical expectations on various types of contributions, like bug reports or patches to packaging or translations
• default configuration for AI-assisted code reviews on Salsa that projects could enable and supplement with their own instructions on top

In addition to that it would be helpful for Debian, as a project, to reach out to AI service providers to:

• encourage them to improve sustainability (where needed)
• investigate and fix problems causing excessive scraping load on systems
• provide AI resources for Debian usage, for example in CI infrastructure or to provide equal development support opportunities for Debian developers who cannot afford paid AI services
• improve coding outputs of their models in the Debian context if/when systematic deficiencies in the output are found by us

Questions? Feedback? Just ask here or here.

22 Aug 2026 7:30pm GMT

This YouTube video about the Cashier Girl Meme is interesting in the context of AI systems that generate images of people and can communicate with people, hotter than any real human is an achievable goal [1].

Stand Up Maths has an interesting Youtube video about LLMs solving maths problems which I highly recommend watching (it does not require any real knowledge of maths), I think this opens the door to attacks on well established cryptologic systems [2].

Adam Conover made an insightful YouTube video about how and why Hollywood is now unable to make good sitcoms and why this is bad for society [3].

Sky Croeser wrote an interesting and insightful blog post about topics covered at the "Digital and sexual citizenship in an age of social media bans: Interrogating the rights of children and young people conference" [4].

Zane wrote a very informative blog post about reverse engineering a trojaned Android projector with Claude Code [5]. We need much better security on home networks to break the business model for this sort of thing.

Renee Stonebraker's article "Puritans Wouldn't Eat Pussy, So They Invented the Western" has a lot of interesting information about early days of colonising the US, and not much about eating pussy [6].

IFLScience has an interesting article about brinicles, icicles of brine that form under sea ice [7].

Nautilus has an interesting article about the Silurian Hypothesis [8].

The Conversation has an intersting article about the pros and cons of no-till farming [9].

Cold War is a 365tomorrows story about bio-warfare which raises several disturbing possibilities we need to guard against [10].

Scott Santens wrote an insightful article describing how a land value tax would reduce rent and solve the housing shortages [11].

Positive News has an interesting article about using OnlyFans to teach people about climate change [12].

The Conversation has an interesting article about cultural safety in healthcare, sounds good, and while we are at it lets deal with sexism [13].

Doctoreww has an interesting web page about ways of displaying different strings to humans and machines, this could result in you running a different command to what you thought you copied from a web site or defeating tools designed to block hostile content [14].

Cory Doctorow wrote an insightful article "Commentary Hell is Other People" about the way rich people want to use AI to replace all people [15]. Also psychologists who help rich people accept being greedy are worthy of a Luigi

The research article "Worship me at the office altar: Why narcissistic leaders resist remote work" is interesting, yet another reason to get rid of narcissistic executives [16].

Renew Economy has an interesting article about clean up costs for mining (which is usually left for the government to pay) and how this could impact renewable energy production facilities [17].

Elvira Bary wrote an insightful article on the Russian financial collapse that is happening now [18].

The Guardian has an interesting article about Afro-American women who travel to South Korea for healthcare because of problems with racism and sexism in American hospitals [19].

The Conversation has an interesting article about the potential for disabled people to be more productive in space than non-disabled people [20].

Krebs has an interesting article about LG banning residential proxy code from apps after the LG store was found to have such code in 42% of it's apps [21].

Robert B Shpiner wrote an insightful article for The Guardian about the death of democracy in the US [22].

• [1] https://www.youtube.com/watch?v=TCn7bA1eg_0
• [2] https://www.youtube.com/watch?v=ZJ8KThKAfbs
• [3] https://www.youtube.com/watch?v=gpSghW4J3ws
• [4] https://tinyurl.com/28b6jclu
• [5] https://zanestjohn.com/blog/reing-with-claude-code
• [6] https://tinyurl.com/2y2b6a58
• [7] https://tinyurl.com/2awjppn5
• [8] https://tinyurl.com/2y89gftt
• [9] https://tinyurl.com/2b27vo8o
• [10] https://365tomorrows.com/2024/03/27/cold-war-2/
• [11] https://tinyurl.com/2aqkn4z6
• [12] https://tinyurl.com/2dy5vy8g
• [13] https://tinyurl.com/25rld7v3
• [14] https://doctoreww.github.io/EvilFontTool/
• [15] https://tinyurl.com/2c2guu89
• [16] https://tinyurl.com/27kq4qqu
• [17] https://tinyurl.com/2blp477w
• [18] https://tinyurl.com/27aybgge
• [19] https://tinyurl.com/29covbrp
• [20] https://tinyurl.com/27qdj6co
• [21] https://tinyurl.com/22pxub8v
• [22] https://tinyurl.com/25zf4hnp

22 Aug 2026 4:05pm GMT

A new minor release 0.4.28 of RProtoBuf arrived on CRAN today. RProtoBuf provides R with bindings to the Google Protocol Buffers ("ProtoBuf") data encoding and serialization library used and released by Google, and deployed very widely in numerous projects as a language and operating-system agnostic protocol. The new release is also already as a binary via r2u.

This release corrects a really old bug. Troy found, when working on gRPC based extensions, which is in and by itself exciting, that a small part of our interface surface (for service descriptors) was just wrong confusing single and double underscores. adjusts to a change upstream. This has been corrected. I updated a few of the usual continuous integration parts, updated a help page for a newly-added nag by CRAN, and also got a last-minute round of noodling in as the JSS paper vignette was still referencing OmegaHat which the CRAN URL checker objected to. I created a quick one-off repo to serve pdf files should the need arise again, and rebuilt the vignette linking to it. No other changes.

The following section from the NEWS.Rd file has all details and links.

Changes in RProtoBuf version 0.4.28 (2026-08-21)

• Standard maintenance of continuous integration

• The type help page has received a usage section

• Cleanup of several methods for ServiceDescriptor, correct several other declaration (Troy Hernandez in #117 fixing #116)

• Adjusted vignette reference to Omegahat paper to alternate location

Thanks to my CRANberries, there is a diff to the previous release. The RProtoBuf page has copies of the (older) package vignette, the 'quick' overview vignette, and the pre-print of our JSS paper. Questions, comments etc should go to the GitHub issue tracker off the GitHub repo.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. If you like this or other open-source work I do, you can sponsor me at GitHub.

22 Aug 2026 12:24pm GMT

$ wget https://cloud.debian.org/images/cloud/trixie/daily/latest/debian-13-generic-amd64-daily.qcow2

$ export SIZE=$(stat -Lc%s debian-13-generic-amd64-daily.qcow2)
$ virsh vol-create-as default dev-vm $SIZE --format qcow2
$ virsh vol-upload --pool default dev-vm debian-13-generic-amd64-daily.qcow2

$ echo root > password.txt
$ virt-install --name dev-vm --memory 4096 --noreboot \
        --os-variant detect=on,name=linux2024 \
        --disk vol=default/dev-vm \
        --import \
        --boot uefi \
        --cloud-init root-password-file=password.txt,clouduser-ssh-key=$HOME/.ssh/.ssh/id_ed25519,disable=on

Starting install...
Allocating 'virtinst-ns9oa7_i-cloudinit.iso'                | 368 kB  00:00     
Transferring 'virtinst-ns9oa7_i-cloudinit.iso'              | 368 kB  00:00     
Creating domain...                                          |         00:00     
Connected to domain 'dev-vm'

BdsDxe: starting Boot0001 "UEFI Misc Device" from PciRoot(0x0)/Pci(0x2,0x3)/Pci(0x0,0x0)

Booting `Debian GNU/Linux'

Loading Linux 6.12.101+deb13-amd64 ...

Loading initial ramdisk ...

EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path
EFI stub: UEFI Secure Boot is enabled.
[    0.000000] Linux version 6.12.101+deb13-amd64 (debian-kernel@lists.debian.org) (x86_64-linux-gnu-gcc-14 (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44) #1 SMP PREEMPT_DYNAMIC Debian 6.12.101-1 (2026-08-05)
[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-6.12.101+deb13-amd64 root=PARTUUID=2b4578e2-9d2e-4b32-b6a4-b5b2ca607ef6 ro console=tty0 console=ttyS0,115200 earlyprintk=ttyS0,115200 consoleblank=0
...

# open a serial console to the VM
$ virsh console dev-vm
# access the graphical console
$ virt-manager
# Access the VM via SSH with the precreated cloud user "debian"
$ virsh domifaddr dev-vm
 Name       MAC address          Protocol     Address
-------------------------------------------------------------------------------
 vnet7      52:54:00:23:e6:61    ipv4         192.168.122.225/24
$ ssh debian@192.168.122.225

22 Aug 2026 8:39am GMT

21 Aug 2026 11:09am GMT