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Re: [Qemu-devel] [PATCH] resent: x86/cpuid: propagate further CPUID leaf
Re: [Qemu-devel] [PATCH] resent: x86/cpuid: propagate further CPUID leafs when -cpu host
Tue, 25 May 2010 16:47:44 +0300
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On 05/25/2010 04:26 PM, Anthony Liguori wrote:
On 05/25/2010 08:21 AM, Andre Przywara wrote:
What's the benefit of exposing this information to the guest?
That is mostly to propagate the cache size and organization
parameters to the guest:
>> +/* safe CPUID leafs to propagate to guest if -cpu host is specified
>> + * Intel defined leafs:
>> + * Cache descriptors (0x02)
>> + * Deterministic cache parameters (0x04)
>> + * Monitor/MWAIT parameters (0x05)
>> + *
>> + * AMD defined leafs:
>> + * L1 Cache and TLB (0x05)
>> + * L2+L3 TLB (0x06)
>> + * LongMode address size (0x08)
>> + * 1GB page TLB (0x19)
>> + * Performance optimization (0x1A)
>> + */
Since at least L1 and L2 caches are mostly private to vCPUs, I see no
reason to disguise them.
But in practice, what is it useful for?
See my other mail.
Just because we can expose it doesn't mean we should.
What's the point of -cpu host then?
error compiling committee.c: too many arguments to function