Re: [patch] x86, pat: fix reserve_memtype() for legacy 1MB range

From: H. Peter Anvin
Date: Sat Jan 17 2009 - 18:25:29 EST

Pavel Machek wrote:
> On Fri 2009-01-09 14:48:04, Suresh Siddha wrote:
>> On Fri, Jan 09, 2009 at 02:39:31PM -0800, H. Peter Anvin wrote:
>>> Suresh Siddha wrote:
>>>> Here X is trying to map first 8KB of memory using /dev/mem. Existing
>>>> code treats first 0-4KB of memory as non-RAM and 4KB-8KB as RAM. Recent
>>>> code changes don't allow to map memory with different attributes
>>>> at the same time.
>>> Why was 0-4 KB marked as non-RAM? It is most definitely RAM, and should
>>> be WB.
>> While in reality it is RAM, we have CONFIG_STRICT_DEVMEM which doesn't allow
>> apps to map RAM pages using /dev/mem. And to allow app's to map the
>> legacy 0-4KB bios data page, we consider it as non-RAM.
> Fix config_strict_devmem? Ram is ram, and we should not li for
> strict_devmem benefit...

*As far as I understand* this is only considered non-RAM for the purpose
of strict_devmem?


H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

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