Re: [PATCH] x86: fixed mtrr change WP to WB

[H. Peter Anvin]

Yinghai Lu wrote:
> >  If the mptable should be modified, it should be copied to kernel memory and
> > modified there.  Modifying it in-place is both unsafe and, in general,
> > simply will not work.
>
> but
>
>          * 1) Scan the bottom 1K for a signature
>          * 2) Scan the top 1K of base RAM
>          * 3) Scan the 64K of bios
>          */
>         if (smp_scan_config(0x0, 0x400, reserve) ||
>             smp_scan_config(639 * 0x400, 0x400, reserve) ||
>             smp_scan_config(0xF0000, 0x10000, reserve))
>                 return;
>
> and all these areas are reserved already.
>
> wonder if we could only modify mpf->mpf_physptr to point to another
> mpc and reuse mpf?

Obviously, if you have already modified a table, you should save a 
pointer to it, and not rely on the kernel scanning later.

	-hpa
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