Re: [tip:x86/platform] x86/PCI/mmcfg: Switch to ECAM config mode if possible

From: Andi Kleen
Date: Thu Jun 29 2017 - 23:19:02 EST


> Hi Thomas,
>
> Would this patch actually void the commit:

Yes it does. My origina; patches were opt-in for this reason, but Thomas doesn't
believe in historical or other people's experience.

But MCFG problems were a long time ago and noone uses these systems anymore,
so perhaps he is right.

-Andi

>
> commit a0ca9909609470ad779b9b9cc68ce96e975afff7
> Author: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
> Date: Mon Jan 14 17:31:09 2008 -0500
>
> PCI x86: always use conf1 to access config space below 256 bytes
>
> Thanks to Loic Prylli <loic@xxxxxxxx>, who originally proposed
> this idea.
>
> Always using legacy configuration mechanism for the legacy config space
> and extended mechanism (mmconf) for the extended config space is
> a simple and very logical approach. It's supposed to resolve all
> known mmconf problems. It still allows per-device quirks (tweaking
> dev->cfg_size). It also allows to get rid of mmconf fallback code.
>
> Signed-off-by: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>