Message-ID: <4AD36B42.9060608@linux.intel.com>
Date: Mon, 12 Oct 2009 10:45:38 -0700
From: Arjan van de Ven <arjan@linux.intel.com>
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To: "H. Peter Anvin" <hpa@zytor.com>
CC: mingo@redhat.com, linux-kernel@vger.kernel.org,
       torvalds@linux-foundation.org, arjan@infradead.org, hmh@hmh.eng.br,
       rdreier@cisco.com, tglx@linutronix.de, mingo@elte.hu,
       linux-tip-commits@vger.kernel.org
Subject: Re: [tip:x86/pat] x86: Relegate CONFIG_PAT and CONFIG_MTRR configurability
 to EMBEDDED
References: <20091011103302.62bded41@infradead.org> <tip-c03cb3149daed3e411657e3212d05ae27cf1a874@git.kernel.org> <4AD36723.5040502@zytor.com>
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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@infradead.org>
>> AuthorDate: Sun, 11 Oct 2009 10:33:02 -0700
>> Committer:  Ingo Molnar <mingo@elte.hu>
>> 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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