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Message-ID: <86802c440801192255t3181d4cav7c55fee2b246f356@mail.gmail.com>
Date: Sat, 19 Jan 2008 22:55:25 -0800
From: "Yinghai Lu" <yhlu.kernel@gmail.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] x86: disable_mtrr_trim only need for x86_64
Cc: "Ingo Molnar" <mingo@elte.hu>, "Andi Kleen" <ak@suse.de>,
       LKML <linux-kernel@vger.kernel.org>,
       "Jesse Barnes" <jesse.barnes@intel.com>,
       "Andrew Morton" <akpm@linux-foundation.org>
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References: <200801192045.17291.yinghai.lu@sun.com>
	 <4792DE0C.9060906@zytor.com>
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On Jan 19, 2008 9:37 PM, H. Peter Anvin <hpa@zytor.com> wrote:
> Yinghai Lu wrote:
> > [PATCH] x86: disable_mtrr_trim only need for x86_64
> >
> > mtrr_trim_uncached_memory is only used in x86_64,
> >
> > so disable_mtrr_trim is not needed for x86_32
> >
> > Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
>
> That seems like a bug, and if so this patch goes the wrong direction.
> (If the 32-bit code has another solution for the same problem, they
> should be unified.)
>
> The trimming of uncachable memory affects both 32- and 64-bit kernels;
> it's the same hardware, and even 32-bit kernels (with PAE) can access
> memory above 4 GB.
>

the trim fix for x86_64 is update end_pfn, and use that as max_pfn,
and max_low_pfn in setup_arch.

but i386 is setup_arch is only using max_low_pfn.

to make you happy, the simple way is update e820 table so code could
be unified between i386 and x86_64

update the e820 table by checking mtrr like checking gart hole...

is that OK?

YH
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