Re: [PATCH] ACPI: NUMA: Only parse CFMWS at boot when CXL_ACPI is on

[Gregory Price]

On Thu, Mar 05, 2026 at 12:14:52AM +0000, Huang, Kai wrote:
> On Wed, 2026-03-04 at 18:56 -0500, Gregory Price wrote:
> > 
> > This basically says if specifically CXL_ACPI is built out, the NUMA
> > structure is forever lost - even though it's accurately described by
> > BIOS.  
> > 
> 
> The normal NUMA info described in SRAT is still there.  It only avoids
> detecting CFMWS, which doesn't provide any NUMA info actually -- that's why
> kernel assigns a 'faked' NUMA node for each of them.
> 
> So we are not losing anything AFAICT.

Well, I'm mostly confused why there are CEDT entries for hardware that
presumably isn't even there - unless this platform is reserving space
for future hotplug.  Just want to make sure we're not adjusting for
strange firmware behavior.

The only platform we've seen this behavior on previously was QEMU, but
that was because it never emitted SRAT, so i was wondering if there's
odd firmware behavior going on (emitting CEDTs when it shouldn't) before
we jump to dropping nodes that would have otherwise have been present
on existing systems who might have compiled CXL_ACPI out.

You are taking something away by nature of compiling something out by
default that was previously not compiled out by default.

~Gregory