glibc 2.42 in questing

[Simon Chopin]

On mer. 13 août 2025 09:04:22, Aaron Rainbolt wrote:
> On Wed, Aug 13, 2025 at 7:39 AM Simon Chopin <simon.chopin at canonical.com> wrote:
[snip]
> > Now, if I'm wrong about lack of major breakage, you want to watch out
> > for the following symptoms in your autopkgtests, build logs, or bug
> > reports:
> >
> > * FTBFS due to missing termio.h
> >   Your package is using some really outdated interfaces that were
> >   already obsolete when the Berlin Wall fell. Please look into
> >   termios.h.
> > * ARM issues only on modern ARM64 processors (e.g. Apple M4), around coroutine
> >   or exception-handling code. Tobias, do we even support running on M4
> > hardware!?
>
> Does "M4 hardware" mean running directly on Apple's M4 CPU bare metal,
> or does it also include running inside a virtual machine under
> Parallels, VMware Fusion, UTM, etc.? If this is a problem inside
> virtual machines, I personally don't think that would be acceptable.
> If it's a baremetal-only issue, then meh, probably not that big of a
> deal. Just my 2 cents on the matter.

Don't worry too much about this. I'm not saying those systems are
broken, just that *if* you see issues looking like that on those systems
then this upload might be the cause.

The details are a bit beyond my knowledge, but basically the SME matrix
storage is disabled when calling setjmp() for consistency with
longjmp(). It's unlikely to affect Ubuntu since we don't generate those
opcodes by default and even then, why would you call setjmp() in the
middle of matrix operations, but OTOH it's the kind of thing that's a
nightmare to debug, which is why I figured I would mention it.

As to whether or not your VMs are affected, I wouldn't know. Check
/proc/cpuinfo to see if you have SME in your VM?

Cheers,
Simon
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