Re: [Valgrind-users] Question about Valgrind tool in Intel new platform

[Tom H. <to...@co...>]

On 20/04/2022 13:18, Yang Zhong wrote:
> On Wed, Apr 20, 2022 at 09:37:17AM +0100, Tom Hughes wrote:
>> On 20/04/2022 09:01, Yang Zhong wrote:
>>
>>> So, from above issue in Intel new platform, the valgrind need do some enablings to be compatible
>>> with on new platform? Seems valgrind tool can't identify the real HW platform because cpuid can't
>>> read correct register value. thanks!
>>
>> When running under valgrind you are running on an emulated CPU not
>> the real CPU and the results of cpuid will reflect the capabilities
>> of that emulated CPU rather than the real CPU.
>>
>> Do the bits that you are trying to check reflect something (like new
>> instructions) that valgrind will need to be concerned about?
>>
> 
>    Thanks Tom for your quickly response!
> 
>    The AMX is the NEW feature in Intel new platform and from host, we can
>    find below cpu flags:
> 
>    amx_bf16, amx_tile, amx_int8

That tells me nothing.

>    The SPEC can be found in:
>    https://software.intel.com/content/dam/develop/external/us/en/documents/architecture-instruction-set-extensions-programming-reference.pdf

No I'm not going to spend my day digging through thousands of pages
of the latest instruction set reference trying to figure out what
exactly this feature is...

>    The issue I mentioned should be related with AMX features missed in
>    valgrind emulated CPU. If someone will implement this feature on valgrind,
>    I can help verify. Thanks!

Again until we know what "AMX features" are it's impossible to comment
in any detail.

If AMX features involved new instructions then yes it will definitely
need somebody to do the work to add support for them.

Tom

-- 
Tom Hughes (to...@co...)
http://compton.nu/