Re: [PATCH v2 02/13] qemu/atomic: Drop special case for unsupported compiler

[Daniel P . Berrangé]

On Thu, Nov 26, 2020 at 11:49:28AM +0000, Peter Maydell wrote:
> On Thu, 26 Nov 2020 at 11:29, <marcandre.lureau@redhat.com> wrote:
> >
> > From: Philippe Mathieu-Daudé <philmd@redhat.com>
> >
> > Since commit efc6c070aca ("configure: Add a test for the
> > minimum compiler version") the minimum compiler version
> > required for GCC is 4.8, which has the GCC BZ#36793 bug fixed.
> >
> > We can safely remove the special case introduced in commit
> > a281ebc11a6 ("virtio: add missing mb() on notification").
> >
> > With clang 3.8 (xenial amd64) __ATOMIC_RELAXED is defined, so the chunk
> > to remove (which is x86-specific), isn't reached.
> 
> The minimum clang version enforced by configure is 3.4, not 3.8.
> (Or Apple XCode clang 5.1 -- they use a different versioning scheme!)

We picked clang 3.4 based on fact that is what ships in EPEL7, and
Debian Jessie 3.5.  We then picked the XCode version to match.

Based on our platform support matrix we no longer support Debian
Jessie, and IMHO we also don't really need to consider 3rd party
add-on repos shipping non-default toolschains. So IMHO we could
entirely ignore clang in EPEL7 when picking min versions.

IOW, we are likely justified in picking a new clang version if
someone wants to research what is a suitable min version across
our intended supported distros.

Regards,
Daniel
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