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

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Message-ID: <20250811175756.kqtbnlrmzphpj2lm@pali>
Date: Mon, 11 Aug 2025 19:57:56 +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

Hello Rostyslav, I would like to remind the previous email.
I still do not know which bit in D18F4x044 represents the
EnableCF8ExtCfg config.

On Wednesday 16 July 2025 20:13:20 Pali Rohár wrote:
> 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?