Re: [Xen-ia64-devel] Problem with xen-unstable cset 7937 (grant tabletransfer fix)

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 22 Nov 2005, at 00:46, Magenheimer, Dan (HP Labs Fort Collins) wrote:

> Keir, could you translate the asm statement in gnttab_transfer
> into a cmpxchg (see include/asm-x86/system.h)?  Or is it doing
> something that the macros can't do?
Yes, it can be. The cmpxchg is relying on count_info and domain fields 
being adjacent, by the way. And the construction of old/new values to 
pass to cmpxchg is specific to little endian systems. It might be best 
to define an arch-specific function for atomically stealing a page from 
a domain, although we might get away with defining a endian-aware macro 
for concatenating two u32's into a u64, and turning cmpxchg8b into 
cmpxchg().
> Also, I've attached a patch that shows the differences between
> the x86 and ia64 versions.  If you think it would be possible
> to merge most of these differences (and/or incorporate a
> small number of ifdefs into common/grant_table.c), that
> would be very helpful.
No patch!

 -- Keir


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