As we partially pass through some host GMCH pci registers when display pass-though is enabled, we can't assume we are using fixed host bridge.
--- /dev/null
+diff --git a/tools/firmware/rombios/rombios.c b/tools/firmware/rombios/rombios.c
+index 0aea421..1e5420c 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
init-vgabios-and-set-size
module-reloc
mfn-validity-check-before-shadow-remove
+remove-fixed-host-bridge-check