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

thanks,
suresh


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