Re: [Qemu-ppc] [PATCH 1/2] ppc/kvm: Handle the "family" CPU via alias instead of registering new types

[Thomas Huth]

On 01.02.2017 01:10, David Gibson wrote:
> On Tue, Jan 31, 2017 at 02:11:58PM +0100, Thomas Huth wrote:
>> When running with KVM on POWER, we are registering a "family" CPU
>> type for the host CPU that we are running on. For example, on all
>> POWER8-compatible hosts, we register a "POWER8" CPU type, so that
>> you can always start QEMU with "-cpu POWER8" there, without the
>> need to know whether you are running on a POWER8, POWER8E or POWER8NVL
>> host machine.
>> However, we also have a "POWER8" CPU alias in the ppc_cpu_aliases list
>> (that is mainly useful for TCG). This leads to two cosmetical drawbacks:
>> If the user runs QEMU with "-cpu ?", we always claim that POWER8 is an
>> "alias for POWER8_v2.0" - which is simply not true when running with
>> KVM on POWER. And when using the 'query-cpu-definitions' QMP call,
>> there are currently two entries for "POWER8", one for the alias, and
>> one for the additional registered type.
>> To solve the two problems, we should rather update the "family" alias
>> instead of registering a new types. We then only have one "POWER8"
>> CPU definition around, an alias, which also points to the right
>> destination.
>>
>> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1396536
>> Signed-off-by: Thomas Huth <address@hidden>
> 
> Reviewed-by: David Gibson <address@hidden>
> 
> Updating the otherwise static table of aliases is kind of ugly, but
> then so is registering an extra full type as we do now.
> 
> Is this safe to apply without the follow up patch to vl.c.

Yes. It fixes the problem with "query-cpu-definitions" already. You just
need the other patch to get the output of "-cpu ?" right, too.

 Thomas

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