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Re: [Qemu-devel] Async savevm using userfaultfd(2)
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] Async savevm using userfaultfd(2) |
Date: |
Thu, 13 Oct 2016 09:30:49 +0100 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
* Stefan Hajnoczi (address@hidden) wrote:
> On Wed, Oct 12, 2016 at 4:04 PM, Stefan Hajnoczi <address@hidden> wrote:
> > Perhaps this approach can be prototyped with mprotect and a SIGSEGV
> > handler if anyone wants to get async savevm going. I don't know if
> > there are any disadvantages to mprotecting guest RAM that the kvm kernel
> > module is using. Hopefully in-kernel devices and vhost will continue to
> > work.
>
> I woke up this morning with a strong feeling that a SIGSEGV handler
> won't work with vhost.
YKYBHTLW you wake up with strong feelings about SIGSEGV handlers.
> The problem is that the QEMU process' SIGSEGV
> handler won't be called when the vhost kernel thread faults. Now I'm
> wondering whether userfaultfd will work together with vhost.
I think it should, or at least I think all other kernel things end up being
caught by userfaultfd during postcopy.
Dave
> Stefan
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK