Re: [Qemu-devel] [PATCH 6/6] qapi: discriminate CpuInfo[Fast] on SysEmuTarget, not CpuInfoArch

[Eric Blake <eblake@redhat.com>]

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On 04/26/2018 09:34 AM, Markus Armbruster wrote:
>>
>> Acerbic discovery of the day: @CpuInfoArch has "x86", while configure
>> produces:
>>
>>   TARGET_NAME  TARGET_BASE_ARCH
>>          i386              i386
>>        x86_64              i386
>>
>> Note how "i386" does not match "x86".
> 
> Review fail.
> 
> Just three weeks ago, we could still have fixed query-cpus-fast...

Actually, I think we still can.  We already documented in the 2.12
release notes that the "arch" field of query-cpus-fast is known to be
broken for all but "s390x" (which is really the only arch field that
MUST be correct, as that is the only time we send additional
information).  And introspection can easily see both the enum contents
(if we add something) as well as any other additions to the
query-cpus-fast output union (although that is less likely), to use
those as a witness for whether qemu is new enough to have fixed the
bogus "arch" values.  I'd argue that if we change things right now, with
intent to include the change in 2.12.1, before people start relying on
the bogus "arch" of 2.12, then we should feel free to make
query-cpus-fast output whatever we want for all architectures other than
"s390x", even if it changes the current output of "x86".

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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