Re: [PATCH v2 01/29] x86: treewide: Introduce x86_vendor_amd_or_hygon()

[H. Peter Anvin]

On March 17, 2025 11:10:27 AM PDT, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>On 17/03/2025 5:48 pm, Peter Zijlstra wrote:
>> On Mon, Mar 17, 2025 at 06:32:16PM +0100, Borislav Petkov wrote:
>>> On Mon, Mar 17, 2025 at 05:47:17PM +0100, Ahmed S. Darwish wrote:
>>>> The pattern to check if an x86 vendor is AMD or HYGON (or not both) is
>>>> pretty common.  Introduce x86_vendor_amd_or_hygon() at <asm/processor.h>
>>> So if we need to check "intel too", we do
>>>
>>> x86_vendor_amd_or_hygon_or_intel?
>>>
>>> Nah, this is silly.
>> Would it make more sense to have a Zen1 feature and check that instead?
>>
>> Because, IIRC Hygon is simply a Zen1 copy.
>
>AMD and Hygon the most often compared together, because the Hygon CPUs
>are so close to Zen1/2.
>
>One trick you can do to make this easier is to define vendors IDs as (1U
><< $N).  This leaves all existing code with equality checks working, but
>also lets you check "vendor & (AMD | HYGON)" rather more efficiently.
>
>~Andrew

Jinx.