RE: [Xen-devel] Selective Passthrough Virtualization

["Kaushik Barde" <Kaushik_Barde@xxxxxxxxxxx>]

Thanks Keir,

I understand. 

So, I assume with extra-chipset support you meant something like :

- SVIF ( Self-Virtualized Interfaces) based Sound-cards with its
(addition to sound functions) own memory addressing scheme and audio
processor facilitating virtualized interfaces.

Looks like we may have to Resort to Xen//Dom0 handling of audio 
        - How good is it?

Thanks.

-Kaushik

-----Original Message-----
From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx] 
Sent: Monday, January 22, 2007 12:49 AM
To: Kaushik Barde; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [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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