Re: [Xen-devel] [PATCH] libxc: Add xc_domain_hvm_get_mtrr_type() call

[Razvan Cojocaru <rzvncj@xxxxxxxxx>]

> TBH until someone figures out or explains what overlap actually is I
> don't know if it even needs exporting or taking into account in
> userspace.
http://www.mjmwired.net/kernel/Documentation/mtrr.txt

"Creating overlapping MTRRs:

%echo "base=0xfb000000 size=0x1000000 type=write-combining" >/proc/mtrr
%echo "base=0xfb000000 size=0x1000 type=uncachable" >/proc/mtrr

And the results: cat /proc/mtrr
reg00: base=0x00000000 (   0MB), size=  64MB: write-back, count=1
reg01: base=0xfb000000 (4016MB), size=  16MB: write-combining, count=1
reg02: base=0xfb000000 (4016MB), size=   4kB: uncachable, count=1"

Overlapped MTRRs are MTRRs with the same base, but different types of 
addresses at different offsets.
At least to my understanding.

Thanks,
Razvan Cojocaru


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