RE: [Xen-ia64-devel] Uncached offset: Region 6 -> lower half ofVTi-reserved VM space

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>-----Original Message-----
>From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
>Magenheimer, Dan (HP Labs Fort Collins)
>Sent: Tuesday, June 14, 2005 5:36 AM
>
>I've just pushed a patch to xeno-unstable-ia64.bk which finishes
>the virtual address changes submitted by Intel (Kevin, I think)
>some months ago, where the Xen-reserved VA space was changed from
>       0xf000000000000000-0xf7ffffffffffffff
>               to
>       0xe800000000000000-0xf7ffffffffffffff
>to correspond to one less bit in the guest's virtual address
>space.

You change seems clean to understand. Before submitting a patch for VTI,
I'd like to confirm one thing: whether you want to split cache/uncache
access in different region, or in same region? It seems cleaner to stay
with different region, as Linux currently does. Then if still in region
6 for "uncached" area, 0xd000000000000000 is just same effect as
0xf000000000000000 to hide one bit to guest.

Thanks,
Kevin
>
>The "uncached" portion of Xen's virtual address space was
>still mapped at 0xd000000000000000.  I have moved it
>to 0xe800000000000000 to properly correspond with the
>one-less-bit-guest-VA space.
>
>A couple of changes were required in ivt.S so corresponding
>changes need to be made in vmx_ivt.S.  The only other change
>was the constant value in io.h (a patched file) for
>__IA64_UNCACHED_OFFSET.
>
>Note that I also cleaned up a test to ensure that guest
>data accesses are properly checked against the legal
>address range.  (Not a problem on VTI as these addresses
>could never be generated.)
>
>See changeset 1.1711.  If someone at Intel could submit
>the corresponding vmx_ivt.S change, I would appreciate it.
>
>Thanks,
>Dan
>
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