Re: [PATCH] x86/split_lock: Restore warn mode (and add a new one) to avoid userspace regression

From: Pavel Machek
Date: Thu Oct 06 2022 - 05:04:27 EST


On Wed 2022-09-28 20:24:23, Luck, Tony wrote:
> > So let's revamp the idea of having another option/mode for the split
> > lock detector, which is hereby called "seq" (based on the original
> > "sequential" naming in [0]). Also introduces a Kconfig option to give
> > the option of Linux vendors have a choice what mode should be their
> > default. While at it, fix/improve the documentation about bus locking.
> >
> > [1] https://github.com/doitsujin/dxvk/issues/2938
>
> Why not just use the workaround suggested in that bug report:
>
> "so manual switching from default setting to split_lock_detect=off helps as workaround here"
>
> If you add this extra mode, I'm going to argue that the kernel default
> should be "seq" rather than "warn". So these game players will need
> to add a split_lock_detect=off (or warn) option.

Kernel should not cause userland regressions, and this is one. That
should make it pretty clear what the solution is.

And no, I don't like CONFIG option, either.

Best regards,
Pavel
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