[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD

On 2014/6/26 7:04, Slutz, Donald Christopher wrote:
On 06/24/14 22:49, Chen, Tiejun wrote:
On 2014/5/19 19:22, Gerd Hoffmann wrote:

I think '-vga none' just guarantees the qemu vga cards doesn't occupy
00:02.0, but this doesn't mean others use this specific slot since in
qemu internal, we always pass -1 to assign a slot automatically to
register a PCI device. So in some cases, we can't get this slot as we
expect since that is already assigned previously before we need this.

Yes, -vga, -net nic, -drive if=scsi (maybe more) can internally create
pci devices with auto slot assignment, which will occupy slot 2 indeed.
Use -device instead to create the devices.

PCI: slot 2 function 0 not available for xen-pci-passthrough, in use
by xen-platform

Ah, the xen platform device.  /me looks.  Ah, pc_xen_hvm_init creates
this automatically.  Two options here IMHO:

   (1) Just move it somewhere else explicitly.  For example slot 3, or
       make it a southbridge function (say 00:01.7).
   (2) Don't create it automatically, instead expect management add it
       if needed, using -device xen-plaform,addr=...


Sorry I return this discussion again.

As we discussed here, we should never use -vga xxx to avoid occupying
slot 2. Instead, we will just use -device to create that emulated vga
device as you said like this:

-device VGA,vgamem_mb=8,addr=0x4

But looks this may issue another problem. That is we can't see
anything until the vga driver is initialized. I means if we pass
`-device VGA,vgamem_mb=8,addr=0x4', qemu doesn't expose any vga
interface to BIOS. Right? Or I'm still missing something.

I know for Xen that


also needs to change:

              /* Make cirrues VGA S3 suspend/resume work in Windows
XP/2003 */
              Device (VGA)
-               Name (_ADR, 0x00020000)
+               // Address of the VGA (device F function 0)
+               Name (_ADR, 0x000F0000)

is what I have for:

-device VGA,vgamem_mb=8,addr=0xF.0x0

Do you mean we need to sync devfn with the passed address to work the emulated VGA before the real graphic device driver is called?


I am not sure, but think that QEMU without Xen does this acpi
adjustment at run time.

I also change seabios's config to include more VGA support but
not sure it is needed.

      -Don Slutz


Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.