RE: [Xen-ia64-devel] TR virtualization vs. DCR

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

> Le Mercredi 12 Octobre 2005 10:35, Dong, Eddie a écrit :
> > Dan and All:
> >
> >      Currently both VTI and non-VTI are using machine TC to emulate
> > guest TR, that is a must as machine memory a guest get may be
> > discontiguous and may not be proper aligned. But this 
> introduces another
> > extra issues for guest ld.s.
> [...]
> I am not aware of any other possibility [virtualize DCR].

One of the options with a paravirtualized interface is to
disallow hardware architecural corner-cases that are rarely
used and very difficult/expensive to virtualize.  For
example, in this case, one possibility is to state that
an OS running on top of Xen must expect different behavior
for the ld.s instruction when loading from memory locations
pinned by a (virtual) TR.

I'm not saying this is the best answer for this problem,
but it is a possibility.

> PS: Are you trying to run Windows ?

I have the same question... the above (ld.s from a TR-pinned
location) doesn't occur in Linux does it?  Are you proposing
a fix to a hypothetical problem, or does some other potential
guest operating system make (frequent) use of this?

Thanks,
Dan

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