Re: [tip:x86/pat] x86: Relegate CONFIG_PAT and CONFIG_MTRR configurabilityto EMBEDDED

[Arjan van de Ven]

H. Peter Anvin wrote:
> On 10/12/2009 04:10 AM, tip-bot for Arjan van de Ven wrote:
> > Commit-ID:  c03cb3149daed3e411657e3212d05ae27cf1a874
> > Gitweb:     http://git.kernel.org/tip/c03cb3149daed3e411657e3212d05ae27cf1a874
> > Author:     Arjan van de Ven <arjan@xxxxxxxxxxxxx>
> > AuthorDate: Sun, 11 Oct 2009 10:33:02 -0700
> > Committer:  Ingo Molnar <mingo@xxxxxxx>
> > CommitDate: Mon, 12 Oct 2009 13:06:57 +0200
> >
> > x86: Relegate CONFIG_PAT and CONFIG_MTRR configurability to EMBEDDED
> >
> > MTRR and PAT support (which got added to CPUs over 10 years ago)
> > are no longer really optional in that more and more things are
> > depending on PAT just working, including various drivers and newer
> > versions of X.  (to not even speak of MTRR)
> >
> > Having this as a regular config option just no longer makes sense.
> >
> > This patch relegates CONFIG_X86_PAT to the EMBEDDED category so
> > ultra-embedded can still disable it if they really need to.
>
> Should we combine this with removing the whitelist (which is largely
> vestigial at this point) and replace it with a blacklist (possibly
> empty)?  I still haven't seen any evidence that there are any CPUs which
> have problems, and PAT support go back all the way to Pentium III -- and
> page table attributes can be used all the way back to 386, it just
> excludes the WC type.

I would be in favor of that; other operating systems have been using pat everywhere
since the pII days anyway.
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