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Re: [Xen-devel] gfx-passthrough conflict with pxe booting?

A quick update about the root cause of this issue:
The rombios BIOS used in xen restrict itself to i440FX emulated by Bochs / qemu.
With gfx-passthrough, the pci-host bridge in the domU is replaced by
the device in the host machine.
This makes PCI emulation fail.
The issue can be fixed by simply commenting out this line:

diff --git a/tools/firmware/rombios/rombios.c b/tools/firmware/rombios/rombios.c
index 80980b6..e9c5c4a 100644
--- a/tools/firmware/rombios/rombios.c
+++ b/tools/firmware/rombios/rombios.c
@@ -220,7 +220,7 @@
 // define this if you want to make PCIBIOS working on a specific bridge only
 // undef enables PCIBIOS when at least one PCI device is found
 // i440FX is emulated by Bochs and QEMU
-#define PCI_FIXED_HOST_BRIDGE 0x12378086 ;; i440FX PCI bridge
+//#define PCI_FIXED_HOST_BRIDGE 0x12378086 ;; i440FX PCI bridge

 // #20  is dec 20
 // #$20 is hex 20 = 32

On Wed, Apr 10, 2013 at 9:54 PM, G.R. <firemeteor@xxxxxxxxxxxxxxxxxxxxx> wrote:
> Hi developers,
> I just discovered that with gfx-passthrough=1, the iPXE simply does not work.
> It seems that no NIC is detected by iPXE -- ifstat shows nothing.
> I'm on xen-4.2.1 release, with some IGD passthrough related patches.
> I would like to check if this is a common issue, can anybody help?
> Thanks,
> Timothy

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