[SeaBIOS] [PATCH] Make MTRR region 0xc0000-0x100000 be cached.

Avi Kivity avi at redhat.com
Sun Jan 3 07:15:31 CET 2010

On 01/01/2010 08:23 PM, Kevin O'Connor wrote:
> The current MTRR code in SeaBIOS uses uncached ram for
> 0xc0000-0x100000.  This seems overly pessimistic as "write protect"
> should be sufficient.  (Note, a WP mtrr does not prevent writes - it
> is a caching strategy for memory that can be read-only.)
> I'm not sure how much KVM really uses the MTRRs, but if it does honor
> them this should make bootup a bit faster as it will allow caching of
> the SeaBIOS code.
> This change also clears all the variable mtrrs, and makes sure all the
> mtrrs are set before they are enabled.

kvm ignores the MTRRs, unless device assignment is enabled, in which 
case it honours them.

I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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