Re: [Xen-devel] [PATCH] xencomm, xenmem and hypercall continuation

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 10/11/06 5:49 am, "Isaku Yamahata" <yamahata@xxxxxxxxxxxxx> wrote:

> fix xenmem hypercall for non-trivial xencomm arch(i.e. ia64, and powerpc)
> On ia64 and powerpc, guest_handle_add_offset() effect persists over
> hypercall continuation because its consumed offset is recorced in
> guest domains memory space.
> On the other hand, x86 guest_handle_add_offset() effect is volatile
> over hypercall continuation.
> So xenmem hypercall(more specifically increase_reservation,
> decrease_reservaton, populate_memory and exchange) is broken on
> ia64 and powerpc.
> #ifdef/ifndef CONFIG_X86 is used to solve this issue without breaking
> the existing ABI. #ifdef is ugly, but it would be difficult to solve
> this issue without #ifdef and to preserve the existing ABI simaltaneously.

There must be a cleaner solution. We're not going to ifdef all over the
place.

Does xencomm have to persist the offset increments in guest memory (does the
guest depend on this)? Could it undo these effects across continuations so
that guest_handle_add_offset works properly?

 -- Keir



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel