Cc: Ingo Molnar <mingo@...>, Gabriel C <nix.or.die@...>, Andi Kleen <andi@...>, Andrew Morton <akpm@...>, H. Peter Anvin <hpa@...>, LKML <linux-kernel@...>, Jesse Barnes <jesse.barnes@...>, Mika Fischer <mika.fischer@...>, <balajirrao@...>
The BIOS will setup which areas should be WB in the mtrrs.
Having in the linux the ability to change from overlapping
mtrrs to discrete mtrrs with BIOS support appears very
practical, useful and always safe.
However when it is enabled the default chunk size is still 256M.
If we did not apply chunk size processing by default so we
did not transform any regions from WB to UC by default we could
unconditionally enable the code that yields discrete MTRRs.
Then the CONFIG option and the command line option could be made to
apply to the dangerous bits that change areas from WB to UC. Which
I doubt we will want to have on by default but that can be useful
for people who really want to have X go fast and an uncached SMM
or ACPI area is not a problem. (ACPI we can handle by just copying
the code to a cached area, we can't even discover the SMM area).
Eric
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