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RE: [Xen-devel] HVM domain with write caching going on somewhere to disk

  • To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
  • Date: Thu, 8 Nov 2007 22:08:47 +1100
  • Delivery-date: Thu, 08 Nov 2007 03:09:21 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: Acgh89hmOjf1UcT/R7S91fG2xpfbEgAAJyu6AAAMH9AAAKHtpAAACubg
  • Thread-topic: [Xen-devel] HVM domain with write caching going on somewhere to disk

> > Hmmm... shouldn't the DomU->qemu->device and
> > path's both have visibility to the same buffer cache though?
> No, it's trickier than that. Blkback sends I/O requests direct into
> block subsystem, bypassing the buffer cache. You can see there's
> for confusion therefore!

Ah yes. That would probably do it. So I need to make sure that the
buffer cache is flushed (eg async writes in qemu?)... or maybe get qemu
to talk direct to the block subsystem in the same way... any
suggestions? I've already butchered ioemu to get this working so far
(changed the PCI ID's of the IDE interface so Windows won't detect it)
so I'm not afraid of doing more of it :)



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