sha256sum Illegal instruction on musl amd64

[ben.busybox at backplane.be]

On 1 Mar 2023, at 12:53 PM, Natanael Copa <ncopa at alpinelinux.org> wrote:
> Hi,
> 
> On Wed, 01 Mar 2023 11:55:16 +0100
> "alice" <alice at ayaya.dev> wrote:
> 
>> On Tue Feb 28, 2023 at 11:17 PM CET,  wrote:
>>> Hi,
>>> 
>>> I'm having an intermittent issue with "BusyBox v1.36.0 (2023-01-03 22:49:12
>>> UTC)" (the one from the Docker image busybox:musl) when running on amd64 GitHub
>>> actions runner VMs (azure).
>>> 
>>> When I use sha256sum it is getting terminated with SIGILL, Illegal
>>> instruction. The issue is hard to reproduce but I have a GitHub actions CI/CD
>>> job that I can re-run repeatedly (no changes to code, environment, data input,
>>> etc) that will occasionally have the issue. I managed to capture a core dump.  
>> 
>> this was also reported in http://lists.busybox.net/pipermail/busybox/2023-January/090113.html
>> 
>> it's caused by having a cpu with AVX512 (the github runners do) but not sha_ni,
>> and the code that checks it is broken and misdetects sha_ni support when avx512
>> exists. the github runners don't have sha_ni, so it breaks exactly there.
>> 
>> quite the rare combo :)
>> 
>> i feel this was reported before, but apparently not outside an irc channel..
> 
> I did try to create a fix for it:
> https://github.com/ncopa/busybox/commit/e4ad5e7f2fed8e36d0779d918052169fe9a0bb95
> 
> But it didn't work. I was unable to create a proper core dump and sort
> of gave up. In Alpine we have simply disabled the HWACCEL as it is
> broken.

OK. I've got a bug report to docker library to also disable HWACCEL there until a detection fix can be integrated into the busybox codebase.

https://github.com/docker-library/busybox/issues/166