Re: [PATCH] X86: fix typo PAT to X86_PAT

From: Dave Jones
Date: Fri Jan 18 2008 - 13:57:10 EST


On Fri, Jan 18, 2008 at 10:47:05AM -0800, Venki Pallipadi wrote:

> >This exclusion is going to be a real pain in the ass for
> >distro kernels.
> >It's impossible for example to build a kernel that will now support
> >the MTRR-alike registers on the AMD K6/early Cyrix etc and also
> >support PAT.
>
> Actually, this exclusion will not work at all with the current code.
> Infact it should be PAT selects MTRR, for the current code. As
> pat_init() is called during mtrr init as the rules for how to change PAT
> and how to change MTRR are same. Further, MTRR is always required on
> SMP, as we read the MTRR setting from boot CPU and set it on Aps at boot
> time. We should only remove the /proc/mtrr write permissions with
> CONFIG_PAT. We need to deprecate it for a while before that...
> Ingo, can you remove this PAT MTRR exclusion.

The removal of write-permission also needs to be decided at runtime rather than
compile time, or we screw over the "doesn't support PAT" CPUs in distro kernels.

Dave

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