+ Yazen.
On Mon, Dec 16, 2024 at 02:15:26PM +0100, Rostyslav Khudolii wrote:
> Hi all,
>
> I am currently working on a custom AMD Ryzen™ Embedded R2000 (AMD
> Family 17h) device and have discovered that PCI IO Extended
> Configuration Space (ECS) access is no longer possible.
Perhaps that particular type of system of yours needs some special handling.
Things to try:
* use the latest upstream kernel
* add some debug printks to the paths you mention to see where they fail
Looking at the relevant chapter in the PPR - 2.1.7 or 2.1.8 - that
should still work.
Leaving in the rest for reference.
> Consider the following functions: amd_bus_cpu_online() and
> pci_enable_pci_io_ecs(). These functions are part of the
> amd_postcore_init() initcall and are responsible for enabling PCI IO
> ECS. Both functions modify the CoreMasterAccessCtrl (EnableCf8ExtCfg)
> value via the PCI device function or the MSR register directly (see
> the "BIOS and Kernel Developer’s Guide (BKDG) for AMD Family 15h",
> Section 2.7). However, neither the MSR register nor the PCI function
> at the specified address (D18F3x8C) exists for AMD Family 17h. The
> CoreMasterAccessCtrl 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).
>
> I would be happy to submit a patch to fix this issue. However, since
> the most recent change affecting this functionality appears to be 14
> years old, I would like to confirm whether this is still relevant or
> if the kernel should always be built with CONFIG_PCI_MMCONFIG when ECS
> access is required.
>
> Linux Kernel info:
>
> root@qt5222:~# uname -a
> Linux qt5222 6.6.49-2447-qtec-standard--gef032148967a #1 SMP Fri Nov
> 22 09:25:55 UTC 2024 x86_64 GNU/Linux
>
> Best regards,
> Ros
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
