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Date: Tue, 25 May 2010 16:47:44 +0300
From: Avi Kivity <avi@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] resent: x86/cpuid: propagate further CPUID
	leafs when -cpu host
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Andre Przywara <andre.przywara@amd.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "aurelien@aurel32.net" <aurelien@aurel32.net>

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