Re: [PATCH RFC 4/7] PCI/P2PDMA: Prefer providers with better HMAT performance

[Leon Romanovsky]

On Mon, Aug 17, 2026 at 10:09:42AM -0600, Logan Gunthorpe wrote:
> 
> 
> On 2026-08-16 06:38, Leon Romanovsky wrote:
> >> This feels backwards to me. If ACPI is kind enough to include
> >> information on P2PDMA support then I feel like we should use it
> >> exclusively. Not prioritize the old janky whitelists.
> > 
> > Right now, there is no ACPI support, and I chose to prioritize
> > existing systems that already have some form of support over an ACPI
> > solution that does not yet exist.
> But don't we know whether ACPI is advertising support now? Certainly if
> ACPI indicates support we should use it above all other considerations
> today. Otherwise fall back on the white lists. And that should always
> work. Even on my old hardware because the ACPI on that machine doesn't
> advertise support, so it should fall back on the whitelist. I see no
> need to ever check the whitelist before checking ACPI.

Definitely. This will be addressed in the next version.

Thanks

> 
> Logan