Re: [Xen-devel] Re: changeset 22526:7a5ee3800417

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 16:57 +0000 on 07 Mar (1299517021), George Dunlap wrote:
> > Better to use old_entry.mfn, in the spirit of the original cset
> > ("access-once semantics")?  
> 
> I started to do that, but the one below didn't have an old_entry
> already.  
> 
> > In fact, I suspect that to be safe, you need
> > to do an atomic RMW instead of just an atomic set, and then decide
> > whether the VT-d tables will need to be synced.
> 
> Are we not holding the p2m lock when writing entries?

Good point. :)  I would prefer to use old_entry in both places anyway,
just for consistency with the general approach of reading once.  It
won't be any slower. 

Is this patch intended for 4.1.0?

Cheers,

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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