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

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Message-ID: <CAJDH93vTBkk7a5D0nOgNfBEjGfMhKbFnUWaQ1r6NDLqm0j3kOA@mail.gmail.com>
Date: Tue, 15 Jul 2025 12:43:16 +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

>
> Yes, I would like to get access to ECS via CF8/CFC direct IO for
> debugging purposes, even though MMCFG is enabled and used.
>
> If you can send me a simple patch or any sample / idea how to do it,
> I would be very happy. I was not able to figure out how to enable ECS
> over CF8/CFC.
>

Hi Pali,
I'm sorry for the late reply.

If I understand your request correctly, all you need to do  is patch
the pci_enable_pci_io_ecs() function to use
the different register to set EnableCF8ExtCfg: D18F4x044.

Regards,
Ros