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

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Message-ID: <CAJDH93svLMPM0O_Lq=EgfH6dxXXbnq4QkM6ye_8tyvsRYs8dug@mail.gmail.com>
Date: Tue, 26 Aug 2025 17:07:38 +0200
From: Rostyslav Khudolii <ros@...c.com>
To: Pali Rohár <pali@...nel.org>
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.
>

Hi Pali,

Sorry for the late reply again. So in D18F4x044:
- bit 0. EnableCf8ExtCfg. Enable PCI extended configuration register
access for CFC/CF8
accesses;
- bit 1. DisPciCfgReg. Disable CFC/CF8 Accesses to IO space. When set
to 1, CFC/CF8 accesses are treated as
PCI IO space accesses and not PCI configuration accesses.

Unfortunately, I don't know if this also applies to later families.