[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Live migration with MMIO pages
On 31/10/07 14:03, "Kieran Mansley" <kmansley@xxxxxxxxxxxxxx> wrote: > The symptom of failure is that once live migration has started, trying > to write to an IO page results in it getting stuck in (or a perpetual > loop into) page_fault(). This only happens very occasionally. I've > interpreted it getting stuck in page_fault() as a result of the shadow > paging which (as I understand it) marks the normal page table entries as > read only so that writes to pages trap into the hypervisor and it can > update its dirty set. Yes, but then it should mark the page writable again, so that the access can be re-executed without faulting! So this rather points at some problem with the live-migration shadow mode w.r.t. mmio pages. You're going to have to fix this regardless of whether you prevent xc_domain_save from mapping mmio pages (which isn't itself a bad idea, for the reasons you note). This is because, regardless of whether xc_domain_save ignores mmio pages, that isn't going to change the shadow code's behaviour, and it's almost certainly that which is causing the infinite fault loop. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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