Re: [Qemu-devel] [PATCH 2/5] hostmem: make hostmem global and RAM hotunplg safe

[Stefan Hajnoczi]

On Fri, Apr 12, 2013 at 02:46:41PM +0800, liu ping fan wrote:
> On Thu, Apr 11, 2013 at 6:09 PM, Paolo Bonzini <address@hidden> wrote:
> > Il 01/04/2013 10:20, Liu Ping Fan ha scritto:
> > Finally, please split this patch and patch 3 differently:
> >
> > 1) add HostMemRegions
> >
> > 2) add ref/unref of memory regions to hostmem
> >
> > 3) add MemoryRegion argument to hostmem_lookup, leave it NULL in vring
> >
> As explained above, seem we can not leave it NULL. (In theory, vring
> seated on RAM can not be unplug, since it is kernel.  But I think we
> can not rely on the guest's behavior)

It should be possible to evacuate the vring.  The guest needs to reset
the device so the vring is unmapped.  Then memory can be unplugged.
Reinitializing the device will allocate a new vring and things work
again.

Stefan