sha256sum Illegal instruction on musl amd64

[alice]

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..