[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] Fix xenconsole after aborted save
Keir Fraser wrote: > On 22/04/2009 10:49, "Chris Lalancette" <clalance@xxxxxxxxxx> wrote: > >> Keir Fraser wrote: >>> Another thing to note is I think this problem can only occur if the domU >>> does not support suspend cancellation (advertised as SUSPEND_CANCEL in >>> kernel elf notes -- see xen/xend/XendDomainInfo.py:resumeDomain()). Your >>> kernels should support that feature -- suspend cancellation (a.k.a. Resume) >>> is very likely to be hit-or-miss without it! >> Could you elaborate a bit on this? I was under the impression that suspend >> cancellation was there mostly for the netaccel bits, but I have to admit I >> didn't look at it very closely. What scenarios do the suspend cancel bits >> help? > > Suspend failures (failure to save or to migrate). Also for live > checkpointing/snapshotting. The feature indicates that the guest is happy > for the suspend hypercall to return indicating 'failure/cancelled' and in > which case it can pretty much resume whatever it was doing without any of > the usual resume logic. The alternative is for the toolstack to make it look > like the domain has been restored/migrated, by resetting PV devices and the > like, and this is not much tested and almost inherently fragile. > > The suspend_cancel hook you are thinking of is for any PV devices which *do* > need to know that a suspend was cancelled. Netaccel does for some reason > which I cannot recall. > > Anyway, it is pretty easy and pretty important to support SUSPEND_CANCEL! OK, that makes sense. Thanks Keir! -- Chris Lalancette _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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