RE: [Xen-devel] [PATCH] Make get_page_from_l1e refcount correctly onforeign pagetables.

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

Keir Fraser wrote:
> On 14/05/2009 09:22, "Tim Deegan" <Tim.Deegan@xxxxxxxxxx> wrote:
> 
>>> Perhaps the whole thing gets more convoluted because of c/s 19383,
>>> which added a vcpu parameter for no apparent reason (current is
>>> used for that everywhere afaict).
>> 
>> That parameter is used so that dom0 can modify a PV domU's pagetables
>> using the MMU ops (so dom0 tools can offline a suspect page without
>> domU's help).  In that case, I think the current patch actually
>> fixes a latent bug in refcounting foreign mappings from the target
>> domU to a third (HVM) domain, that was missed in cs 19383.
>> 
>> This is all pretty confusing, though, and Keir may correct me on any
>> or all of it. :)
> 
> I wish I could. I need a damp towel wrapped round my head to
> understand the details of that code now. We may need to step back and
> refactor and rethink
> after 3.4. Hence my reluctance to mess with it now, as I fear
> introducing bugs more significant than latent stubdom issues.

Sorry for slow response.
Yes, that patch is for page ofline as stated by Tim. However, because it is too 
later to 3.4 release, the whole patchset is not in the tree in the end. I will 
re-send the patch once the unstable tree is open again, and we can discuss it 
again at that time.

-- jyh

> 
> -- Keir
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