Re: [PATCH v1 37/40] x86/cacheinfo: Extract out cache self-snoop checks

Andrew Cooper
2025-03-05T19:01:48Z

On 05/03/2025 6:58 pm, Ahmed S. Darwish wrote:
> On Wed, 05 Mar 2025, Andrew Cooper wrote:
> ...
>> It turns out not to be safe in cases where the underlying physical
>> memory changes from cacheable to unchangeable.  By skipping the WBINVD
>> as part of changing the memory type, you end up with spurious writebacks
>> at a later point when the memory is expected to be UC.  Apparently this
>> is a problem for CLX devices, hence the change in the SDM.
> ...
>> CLX (Cascade Lake) != CXL (Compute eXpress Link).
>>
>> CXL is the new PCIe.  (So say the CXL consortium at least.)
>>
> Oh, sorry, you wrote "CLX devices" above, not CXL... Only thing my poor
> brain could come up with was CASCADELAKE_X :)

Oops, so I did.  Sorry.

~Andrew