17 Aug 2017

feedKernel Planet

Linux Plumbers Conference: Tracing/BPF Microconference Accepted into the Linux Plumbers Conference

Following on from the successful Tracing Microconference last year, we're pleased to announce there will be a follow on at Plumbers in Los Angeles this year.

The agenda for this year will not focus only on tracing but also will include several topics around eBPF. As eBPF now interacts with tracing and there is still a lot of work to accomplish, such as building an infrastructure around the current tools to compile and utilize eBPF within the tracing framework. Topics outside of eBPF will include enhancing uprobes and tracing virtualize and layered environments. Of particular interest is new techniques to improve kernel to user space tracing integration. This includes usage of uftrace and better symbol resolution of user space addresses from within the kernel. Additionally there will be a discussion on challenges of real world use cases by non-kernel engineers.

For more details on this, please see this microconference's wiki page.

We hope to see you there!

17 Aug 2017 4:51pm GMT

16 Aug 2017

feedKernel Planet

Linux Plumbers Conference: Trusted Platform Module Microconference Accepted into the Linux Plumbers Conference

Following on from the TPM Microconference last year, we're pleased to announce there will be a follow on at Plumbers in Los Angeles this year.

The agenda for this year will focus on a renewed attempt to unify the 2.0 TSS; cryptosystem integration to make TPMs just work for the average user; the current state of measured boot and where we're going; using TXT with TPM in Linux and using TPM from containers.

For more details on this, please see this microconference's wiki page

We hope to see you there!

16 Aug 2017 12:01am GMT

14 Aug 2017

feedKernel Planet

Dave Airlie (blogspot): radv on SI and CIK GPU - update

I recently acquired an r7 360 (BONAIRE) and spent some time getting radv stable and passing the same set of conformance tests that VI and Polaris pass.

The main missing thing was 10-bit integer format clamping for a bug in the SI/CIK fragment shader output hardware, where it truncates instead of clamps. The other missing piece was code for handling f16->f32 conversions according to the vulkan spec that I'd previously fixed for VI.

I also looked at a trace from amdgpu-pro and noticed it was using a ds_swizzle for the derivative calculations which avoided accessing LDS memory. I wrote support to use this path for radv/radeonsi since LLVM supported the intrinsic for a while now.

With these fixed CIK is pretty much in the same place as VI/Polaris.

I then plugged in my SI (Tahiti), and got lots of GPU hangs and crashes. I fixed a number of SI specific bugs (tiling and MSAA handling, stencil tiling). However even with those fixed I was getting random hangs, and a bunch of people on a bugzilla had noticed the same thing. I eventually discovered adding a shader pipeline and cache flush at the end of every command buffer (this took a few days to narrow down exactly). We aren't 100% sure why this is required on SI only, it may be a kernel bug, or a command processor bug, but it does mean radv on SI now can run games without hanging.

There are still a few CTS tests outstanding on SI only, and I'll probably get to them eventually, however I also got an RX Vega and once I get a newer BIOS for it from AMD I shall be spending some time fixing the radv support for it.

14 Aug 2017 3:16am GMT