Re: [Xen-devel] [PATCH] x86emul: support clzero

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.09.15 at 19:37, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 22/09/15 14:06, Jan Beulich wrote:
>> ... in anticipation of this possibly going to get used by guests for
>> basic thinks like memset() or clearing or pages.
>>
>> Since the emulation doesn't use clzero itself, checking the guest's
>> CPUID for the feature to be exposed is (intentionally) being avoided
>> here. All that's required is sensible guest side data for the clflush
>> line size.
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Where have you found this instruction?  Googling, I have found a
> presentation talking about it being new in the new AMD Zen cores, but I
> still can't locate any technical documentation on the matter.

Sadly no technical documentation so far, despite me pinging for it
after the respective binutils patch
(https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;h=029f3522619e8b77a7b848be23f4c13e50087d8b)
got posted and went in.

Jan


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