RE: [Xen-users] Need clarifications: Xen and winXP HVM: pci direct access, USB, desktop resolution

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of kadafax
> Sent: 24 November 2006 15:34
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] Need clarifications: Xen and winXP HVM: 
> pci direct access, USB, desktop resolution
> 
> Hi list,
> I'm totally new at xen and apologize for my ignorance. What 
> I'm trying 
> to do is the following:
> I've got a laptop with core 2 duo cpu.
> Dom0: Fedora Core 6.
> Dom1: WinXP HVM
> 
> I want to give the Dom1 full access to the wifi card, and the 
> possibility to use USB pen drive. So I've hidden the pci address 
> (according to lspci output) in the kernel's line:
> kernel /xen.gz-2.6.18-1.2849.fc6 pciback.permissive 
> pciback.hide=(0c:00.0)
> 
> and added the following in the dom1's config file:
> pci=['0c,00,0']
> 
> 
> The result when I 'xm create windows':
> 
> Error: pci: failed to locate device and parse it's resources 
> - [Errno 2] No such file or directory: 
> '/sys/bus/pci/devices/0000:0c:00.0/driver'

PCI can't be accesed from HVM domains, because the HVM domain isn't
aware that it's being virtualized. To make this work without modifying
the driver to understand virtualization, the hardware (and Xen) will
have to support IOMMU, which isn't available today. 

I don't know why you get that particular error message, but it's not
really important WHAT error message you get, as it's not going to work
anywyas. 
> 
> I've tried the same with a USB controller to the HVM with the same 
> result. But it wasn't a missing files problem:
> 
> Error: pci: PCI Backend does not own device 0000:00:1d.0
> See the pciback.hide kernel command-line parameter or
> bind your slot/device to the PCI backend using sysfs

I don't know what the difference is, but it's still not going to work. 

You may be able to attach the device to your guest as a "hard-disk", but
my guess is that you're not really wanting to do that. 
> 
> 
> So it's here that I need some clarifications, because I've seen some 
> posts wheres people were talking about successfully attaching a usb 
> printer and some telling that it was impossible in a HVM to 
> give direct 
> access to hardware (fully virtualized so there is a need to 
> develop none 
> open source drivers etc...).
> 
> 
> My second problem is surely independent from the above. It is that I 
> want a bigger desktop resolution in winXP and that the cirrus 
> emulated 
> card only show to the os 4mb of VRAM. I've tried the stdvga=1 in the 
> config file but then the HVM wont boot (blank screen after bios 
> informations).

It's probably possible to increase the VRAM measure. Using stdvga will
not solve anything, as that will not allow a higher resolution (more
likely LESS resolution). Although it SHOULD work - I don't know why it's
not working... Most likely because most people use the CIRRUS logic
version of the device-model, and it's just got broken... :-(

> 
> I must be totally wrong somewhere...

I don't think so, you're just trying to do things that aren't supported
by Xen at the moment. 

--
Mats
> Thanks for any input.
> Regards,
> kfx
> 
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