Re: [Xen-devel] Re: Install paravirtualized drivers after bootingforhigh-performance IO

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> I am wondering if device management, like vga, would share the same
> architecture as block device? if that is the case, would vga be accessed by
> guest os directly?
> if that is not the case, shall we have to base it on X11 system?

Right now, a VGA video card is emulated by the ioemu device model in dom0, 
which displays the current screen state in an X11 window.  The guest is not 
aware of this.

It may well be that initially the block and net drivers are made Xen-aware but 
the VGA device continues to be an emulated PCI device.

At some stage in the future, there may be a "virtual framebuffer" device that 
will be Xen-aware and use shared memory like the block and net drivers.  This 
may give better performance and thus be preferable to the fully emulated 
graphics device for desktop systems.  This is likely to be some time after 
the Xen-aware block / net devices.

Even further into the future, we might see a high performance Xen virtual 3D 
device.  This is some way off, though.

HTH,
Mark

> if all above is wrong, will u please give me some outline of the device
> achitecture?
>
> Miao
>
> StarSoftComm.com
>
>
> ----- Original Message -----
> From: "Mark Williamson" <mark.williamson@xxxxxxxxxxxx>
> To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
> Cc: "Miao Feng" <miaofeng@xxxxxxxxxxxxxxxx>
> Sent: Friday, May 13, 2005 11:33 PM
> Subject: Re: [Xen-devel] Re: Re: Install paravirtualized drivers after
> bootingforhigh-performance IO
>
> >     As i recognized, paravirtulization is an implemention of high
> > performence virtulization in non-VT box, pure virtulization needs no
> > modification on guest os, but paravirtulization do needs. Is that right?
>
> Yes, that's all correct.
>
> >     If so, guest os on VT cpu will provide no paravirtulization?
>
> A fully virtualised environment will be available for guests on a VT CPU,
> so they won't *need* any modifications in order to run.  However, for good
> IO performance, you're likely to want to install Xen-aware device drivers
> which will be compatible with the existing frontend/backend scheme.
>
> Other fully virtualised environments (e.g. VMWare) also sometimes provide
> higher-performance drivers that are aware of the environment.  In Xen's
> case we have Xen-aware drivers already but they need to be adapted to run
> in a VT virtual machine
>
> HTH,
> Mark
>
> >     Any suggestions?
> >
> > Miao
> > StarSoftComm.com

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