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Re: [Xen-devel] Selective Passthrough Virtualization

  • To: Kaushik Barde <Kaushik_Barde@xxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
  • Date: Mon, 22 Jan 2007 08:48:52 +0000
  • Delivery-date: Mon, 22 Jan 2007 00:48:48 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: Acc97GP068IPIZh0SGiVDIKFOk5tcwAFcAnr
  • Thread-topic: [Xen-devel] Selective Passthrough Virtualization

On 22/1/07 6:13 am, "Kaushik Barde" <Kaushik_Barde@xxxxxxxxxxx> wrote:

> I was trying to get Xen-FC5 DOM0 to allow Windows-XP to have 100% control of
> the sound device on the VT enabled HW platform.  After poking at this for a
> bit we ended up in a place where we though the current Xen didn't support this
> without having custom drivers that understood it was being virtualized.   Have
> you found a way around this?

It's unlikely to be possible because the device's DMA engine will expect to
be programmed with physical memory addresses, but the Windows guest only
sees virtualised physical addresses so it will program incorrect values and
DMA to random places. Extra chipset support (which isn't yet available) is
required to support real device drivers in fully virtualised guests.

 -- Keir

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