linux-kernel - Re: PCI IO ECS access is no longer possible for AMD family 17h

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Message-ID: <20250716181320.rhhcdymjy26kg7rq@pali>
Date: Wed, 16 Jul 2025 20:13:20 +0200
From: Pali Rohár <pali@...nel.org>
To: Rostyslav Khudolii <ros@...c.com>
Cc: Ingo Molnar <mingo@...nel.org>, Yazen Ghannam <yazen.ghannam@....com>,
	Borislav Petkov <bp@...en8.de>,
	Filip Štědronský <p@...narg.cz>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	x86@...nel.org
Subject: Re: PCI IO ECS access is no longer possible for AMD family 17h

On Wednesday 16 July 2025 10:03:40 Rostyslav Khudolii wrote:
> > Hello, thank you for information.
> >
> > Just I would like to know, where did you find information that the
> > EnableCF8ExtCfg register was moved to D18F4x044? It is documented in
> > some AMD specification?
> >
> > I did not find anything regarding this change.
> 
> I mentioned the exact specification in my first message. It's under
> NDA, unfortunately.

Do you know if this applies only for AMD family 17? Or also for later
fam 18, 19 and 1a?

And for confirmation, which bit represent the EnableCF8ExtCfg in PCI
config space register D18F4x044? It is still 14th bit like in family 16h?

Just for explanation, in your first message you wrote:

  "register still exists but is now located at a different address (see
  the "Processor Programming Reference (PPR) for AMD Family 17h", Section 2.1.8)."

Document named "Processor Programming Reference (PPR) for AMD Family 17h
Models 01h,08h, Revision B2 Processors" with revision information
"54945 Rev 3.03 - Jun 14, 2019" is publicly available at AMD web:

https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/programmer-references/54945-ppr-family-17h-models-00h-0fh-processors.zip

I looked into that document into section 2.1.8 "PCI Configuration Legacy Access"
and there is not related to EnableCF8ExtCfg.

So I was somehow confused to which section / document you are referring.
And now if I understand correctly, you have NDA documentation with the
same title as the above public one, but with the different content, right?