Re: [Xen-devel] RESEND [Xen-unstable][Qemu-xen] HVM Guest reading of Expansion ROM from passthroughed PCI device returns data from emulated VGA rom

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Sun, Sep 22, 2013 at 05:00:58PM +0200, Sander Eikelenboom wrote:
> 
> >> I'm trying to get secondary vga-passthrough on a HVM guest to work with a 
> >> AMD HD6570 and the native kernel radeon driver and kernel modesetting.
> >> So the guest still gets the emulated stdvga or cirrus device(used in my 
> >> case here) as primary/boot vga adapter.
> >> 
> >> - When i don't passthrough the radeon card, the linux native radeon driver 
> >> loads fine.
> >> - When i do passtrough the device to a HVM with the same kernel:
> >>   The driver in the guest tries to read the pci expansion rom from the 
> >> passthroughed device to get the vbios.
> >>   The driver reports a successful read, but fails because it can't find 
> >> the right string at the right offset.
> >> 
> 
> > Did you try with qemu-dm-traditional aswell? Does it have the same problem? 
> 
> Hi Pasi,
> 
> Yes i did and yes the same problem.
> From what i recall i used to have succes with vga passthrough with a 
> secondary vga card, but that was some time ago.
> I don't know which of the components (xen, dom0 kernel, domU kernel, radeon 
> driver, qemu has changed in such a way that it fails to work now ...
> 
> 
> But in the mean time i tried to debug it further and from what i can see:
> - Only the io port en mem of the pci device are mapped through the hypervisor.
> - The rom is not, (a hypercall to do the memory mapping is never made) i 
> tried several things to get it to do the mapping, but so far failt to do so.
> - It seems to be a 64bit capable device, some code comments and git commit 
> messages seem to suggest that there were/are some problems with that (in the 
> way the involved components interact)
> 

Yeah, there has been some patches related to that, and I think still some open 
bugs..

Btw did you try with Xen 4.3? Or 4.2? 

-- Pasi


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