On 1 Apr 2006, at 20:45, Jimi Xenidis wrote:
unsigned long evtchn_upcall_bits;
We'd have to group more than just the mask and pending flags into
that long on x86 as otherwise we change the size of a public
structure.
No size change, those two elements are padded to a long to accommodate
the size and alignment of evtchn_pending_sel; so the size remains the
same.
Well that is true. I'd still like to see how big the patch would be to
hide accesses of the pending flag behind a macro, and how clean that
would end up being.
There maybe also be the issue of non-atomic updates of the mask flag,
but that mostly only happens in xenlinux. IA64 and x86 can update
distinct bytes separately and atomically, but I'm not sure if powerpc
guarantees writes are atomic at byte granularity? That flag gets
touched quite a lot when running xenlinux, so we wouldn't want to make
the accesses anything other than ordinary writes on x86 and ia64.
That's one of the benefits for us of currently defining the mask flag
in a separate uint8_t.
-- Keir
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home