Re: Cuirass instability on aarch64 systems

[guix]

Hi,

TL;DR: To mitigate this, add `GUILE_JIT_THRESHOLD=-1' as an environment
variable for Cuirass. If you use the cuirass package from the guix
channel you should be able to use `package-with-patches' and the
attached patch.

On 2024-01-21T16:16:57+0100, Roman Scherer wrote:
> 
> Hi Guix,
> 
> I'm running Cuirass for one of my channels on an aarch64 VM on the Hetzner
> Cloud. When I visit the Cuirass web interface it sometimes serves the page,
> but most of the time it just serves a blank page.

I have been tracking down the exact same error last week.

My debbuging showed that a related issue has been reported to
guile-fibers in [0]. There, Andy Wingo suggested that it might be bad
codegen for atomics[1]. I tried the test case in [0] for guile commits
33e07fc56c18d4f3ffbfd53c4a8300bb2b5e49ba which should be the first
commit to be using the atomic instructions and it failed while it
succeeded with the previous commit. I also tried applying only part of
33e07fc56c18d4f3ffbfd53c4a8300bb2b5e49ba and found that applying the
changes for `compile_atomic_scm_swap_immediate' also makes the test
fail. Unfortunately, I'm not proficient in assembly, atomics and JIT and
don't see anything wrong with it. Even worse, I definitely should be
doing other things right now :D and haven't had time to report my
findings. Feel free to do so :). Else, I might find some time next week.

> [...]
> Recently I submitted this patch [2] to guile-fibers to get my system
> updated. There were no substitutes available and I had to build the package on
> my server. Unfortuntly that build never completed it just hang in the tests.

I too had that problem and was able to work around it by building it on
my x86_64 laptop using transparent emulation. I don't know if this is
related and haven't tested it with `GUILE_JIT_THRESHOLD=-1'.

I hope this helps

vicvbcun

[0]: https://github.com/wingo/fibers/issues/83
[1]: https://github.com/wingo/fibers/issues/83#issuecomment-1538427808

cuirass-disable-jit.patch
Description: Text document