<![CDATA[iGPU PCI passthrough: new experimental packages need testers]]>⚠ DO NOT TEST THIS IN PRODUCTION⚠

I did a Proof-of-Concept to improve the iGPU passthrough situation in the case where the vbios is not in the ROM BAR. This would usually fail in the guest because the guest amdgpu or i915driver would not be able to find the vbios.
I would like to share this PoC with you to gather feedback / testing.

⚠ This is not at all a production ready solution, as you will see with the manual steps which are needed to test this.

Who should test this?

If you have an host with an iGPU, and the usual 8.3 PCI passthrough procedure described at https://docs.xcp-ng.org/compute/#pci-passthrough does not work because the guest dmesg prints something like

Invalid PCI ROM header signature: expecting 0xaa55, got 0x4556

or

Failed to find VBIOS tables (VBT)

or

Unable to locate a BIOS ROM

What has been tested so far

I only tested on an AMD Ryzen Embedded V2748 with Radeon Graphics embedded APU system with a Radeon RX Vega series integrated GPU (PCI vendor id 1002 PCI device id 1636). With this config, I tested that the guest VM was able to correctly probe the GPU with the amgdpu driver.

How to test

  • Install a brand new XCP-ng 8.3 on a test host (or make sure you are up to date with latest 8.3 packages on your test host)
  • Configure XCP-ng user repositories:
wget https://koji.xcp-ng.org/repos/user/8/8.3/xcpng-users.repo -O /etc/yum.repos.d/xcpng-users.repo
  • Update your system with the iGPU PoC packages
yum update --enablerepo=xcp-ng-ysionneau1
  • it will prompt you about importing a new GPG key
  • it should install the following packages:
=============================================================================================================================================================================================================================================================================================================================
 Package                                                                      Arch                                                            Version                                                                                       Repository                                                                  Size
=============================================================================================================================================================================================================================================================================================================================
Updating:
 edk2                                                                         x86_64                                                          20220801-1.7.11.3~romtest.2.xcpng8.3                                                          xcp-ng-ysionneau1                                                          3.0 M
 forkexecd                                                                    x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          2.5 M
 message-switch                                                               x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          4.6 M
 qcow-stream-tool                                                             x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          1.4 M
 qemu                                                                         x86_64                                                          2:4.2.1-5.2.18.1.0.fixrom.1.xcpng8.3                                                          xcp-ng-ysionneau1                                                           16 M
 rrdd-plugins                                                                 x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          9.9 M
 sm-cli                                                                       x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          4.9 M
 squeezed                                                                     x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          1.9 M
 varstored-guard                                                              x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          5.0 M
 vhd-tool                                                                     x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          5.0 M
 wsproxy                                                                      x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          1.1 M
 xapi-core                                                                    x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                           30 M
 xapi-nbd                                                                     x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          3.1 M
 xapi-rrd2csv                                                                 x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          3.0 M
 xapi-storage-script                                                          x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          2.5 M
 xapi-tests                                                                   x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          5.0 M
 xapi-xe                                                                      x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          1.5 M
 xcp-networkd                                                                 x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          4.9 M
 xcp-rrdd                                                                     x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          3.6 M
 xenopsd                                                                      x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          1.4 M
 xenopsd-cli                                                                  x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          2.0 M
 xenopsd-xc                                                                   x86_64                                                          26.1.19-1.2.0.romtest.1.xcpng8.3                                                              xcp-ng-ysionneau1                                                          5.3 M

Transaction Summary
=============================================================================================================================================================================================================================================================================================================================
Upgrade  22 Packages
  • Then you will have to manually dump your iGPU VBIOS to precisely this path: /root/vbios.bin
    • for AMD modern iGPU it should be located in an ACPI table called VFCT, you could first call acpidump -b then use this """one liner"""
python3 -c 'import struct,sys;d=open(sys.argv[1],"rb").read();assert d[:4]==b"VFCT",d[:4];n=struct.unpack("<I",d[4:8])[0];off=struct.unpack("<I",d[0x34:0x38])[0];i=0
while off and off+28<=n:
  pcibus,pcidev,pcifunc,vendor,device,ssvid,ssid,rev,imagelen=struct.unpack("<IIIHHHHII",d[off:off+28])
  if imagelen==0 or off+28+imagelen>n:break
  fn="vbios_%02d_%04x_%04x.bin"%(i,vendor,device);open(fn,"wb").write(d[off+28:off+28+imagelen]);print(fn,"bus=%d dev=%d func=%d vid=%04x did=%04x len=%d"%(pcibus,pcidev,pcifunc,vendor,device,imagelen));off+=28+imagelen;i+=1' vfct.dat
  • Reboot the host
  • Follow the usual PCI Passthrough procedure to pass-through the iGPU PCI device to a Linux VM (a Debian 13 for instance): https://docs.xcp-ng.org/compute/#pci-passthrough
  • Make sure you have the corresponding gpu firmware Debian package installed in your VM: firmware-amd-graphics or firmware-intel-graphics
  • Start the VM
  • Check in the dmesg if the GPU is correctly detected and probed by the driver (amdgpu for AMD for instance)

What to report
Report as replies to this thread, putting text files as attached-files

  • If it worked or not
  • the dmesg of the Linux VM
  • the xl dmesg of the host (dom0)
  • the output of grep xen-pci-passthrough /var/log/xensource.log*
  • the lspci -n -vvv -s SBDF (replace SBDF with the domain:bus:device.function) or your GPU, both in the host (dom0) and in the VM (beware the SBDF will be different!)
  • hexdump -C /boot/vbios.bin | head -n100 on the host (dom0)

Thank you for your help! 🙏

]]>https://xcp-ng.org/forum/topic/12523/igpu-pci-passthrough-new-experimental-packages-need-testersRSS for NodeThu, 08 Oct 2026 10:26:59 GMTThu, 08 Oct 2026 08:07:31 GMT60<![CDATA[Reply to iGPU PCI passthrough: new experimental packages need testers on Thu, 08 Oct 2026 09:32:41 GMT]]>@yannsionneau Yes it works with the stock packages.

]]>https://xcp-ng.org/forum/post/108951https://xcp-ng.org/forum/post/108951Thu, 08 Oct 2026 09:32:41 GMT<![CDATA[Reply to iGPU PCI passthrough: new experimental packages need testers on Thu, 08 Oct 2026 09:27:58 GMT]]>@ovicz It seems your gpu works even without vbios since in your dmesg I can see

[    7.424250] i915 0000:00:08.0: Invalid PCI ROM header signature: expecting 0xaa55, got 0x0000
[    7.424259] i915 0000:00:08.0: [drm] Failed to find VBIOS tables (VBT)

So you're saying that anyway your setup was working even without all those new packages?
Thanks for testing anyway!

]]>https://xcp-ng.org/forum/post/108950https://xcp-ng.org/forum/post/108950Thu, 08 Oct 2026 09:27:58 GMT<![CDATA[Reply to iGPU PCI passthrough: new experimental packages need testers on Thu, 08 Oct 2026 09:20:58 GMT]]>Yes it does see it.
dmesg.txt
Passthrough was working and without that file from your repo.

]]>https://xcp-ng.org/forum/post/108949https://xcp-ng.org/forum/post/108949Thu, 08 Oct 2026 09:20:58 GMT<![CDATA[Reply to iGPU PCI passthrough: new experimental packages need testers on Thu, 08 Oct 2026 09:14:31 GMT]]>@ovicz with the new edk2 package it should help your VM access the vbios in the rom bar.
Does the VM see the gpu?
Can you share the VM dmesg as attached file?
Also, are you trying to passthrough a sriov virtual function? or the entire physical gpu?
Thanks

]]>https://xcp-ng.org/forum/post/108948https://xcp-ng.org/forum/post/108948Thu, 08 Oct 2026 09:14:31 GMT<![CDATA[Reply to iGPU PCI passthrough: new experimental packages need testers on Thu, 08 Oct 2026 09:12:53 GMT]]>@yannsionneau Reverted to stable and I upgraded only that package from your repo. VMs start now. At what should i look for now ?

]]>https://xcp-ng.org/forum/post/108947https://xcp-ng.org/forum/post/108947Thu, 08 Oct 2026 09:12:53 GMT<![CDATA[Reply to iGPU PCI passthrough: new experimental packages need testers on Thu, 08 Oct 2026 08:55:34 GMT]]>@yannsionneau cd /sys/bus/pci/devices/0000:00:02.0/
[11:55 xcp-ng-akz 0000:00:02.0]# echo 1 > rom
[11:55 xcp-ng-akz 0000:00:02.0]# cat rom > /root/vbios.bin
cat: rom: Input/output error
[11:55 xcp-ng-akz 0000:00:02.0]# echo 0 > rom

]]>https://xcp-ng.org/forum/post/108946https://xcp-ng.org/forum/post/108946Thu, 08 Oct 2026 08:55:34 GMT<![CDATA[Reply to iGPU PCI passthrough: new experimental packages need testers on Thu, 08 Oct 2026 08:53:04 GMT]]>Another possibility for you would be to yum downgrade qemu and the xapi packages, everything except edk2 and try again.

]]>https://xcp-ng.org/forum/post/108945https://xcp-ng.org/forum/post/108945Thu, 08 Oct 2026 08:53:04 GMT<![CDATA[Reply to iGPU PCI passthrough: new experimental packages need testers on Thu, 08 Oct 2026 08:51:50 GMT]]>@ovicz in your case it seems the vbios is in the ROM BAR.
You can dump the vbios by doing something like

cd /sys/bus/pci/devices/0000:00:02.0/
echo 1 > rom
cat rom > /root/vbios.bin
echo 0 > rom
]]>https://xcp-ng.org/forum/post/108944https://xcp-ng.org/forum/post/108944Thu, 08 Oct 2026 08:51:50 GMT<![CDATA[Reply to iGPU PCI passthrough: new experimental packages need testers on Thu, 08 Oct 2026 08:48:13 GMT]]>lspci -n -vvv -s 00:02.0
00:02.0 0300: 8086:46d1 (prog-if 00 [VGA controller])
Subsystem: 8086:7270
Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Interrupt: pin A routed to IRQ 16
Region 0: Memory at 60e7000000 (64-bit, non-prefetchable) [disabled] [size=16M]
Region 2: Memory at 4000000000 (64-bit, prefetchable) [disabled] [size=256M]
Region 4: I/O ports at 3000 [disabled] [size=64]
[virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
Capabilities: [40] Vendor Specific Information: Len=0c <?>
Capabilities: [70] Express (v2) Root Complex Integrated Endpoint, MSI 00
DevCap: MaxPayload 128 bytes, PhantFunc 0
ExtTag- RBE+
DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
MaxPayload 128 bytes, MaxReadReq 128 bytes
DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend-
DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR-, OBFF Not Supported
DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF Disabled
Capabilities: [ac] MSI: Enable- Count=1/1 Maskable+ 64bit-
Address: 00000000 Data: 0000
Masking: 00000000 Pending: 00000000
Capabilities: [d0] Power Management version 2
Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
Capabilities: [100 v1] Process Address Space ID (PASID)
PASIDCap: Exec- Priv-, Max PASID Width: 14
PASIDCtl: Enable- Exec- Priv-
Capabilities: [200 v1] Address Translation Service (ATS)
ATSCap: Invalidate Queue Depth: 00
ATSCtl: Enable-, Smallest Translation Unit: 00
Capabilities: [300 v1] Page Request Interface (PRI)
PRICtl: Enable- Reset-
PRISta: RF- UPRGI- Stopped+
Page Request Capacity: 00008000, Page Request Allocation: 00000000
Capabilities: [320 v1] Single Root I/O Virtualization (SR-IOV)
IOVCap: Migration-, Interrupt Message Number: 000
IOVCtl: Enable- Migration- Interrupt- MSE- ARIHierarchy-
IOVSta: Migration-
Initial VFs: 7, Total VFs: 7, Number of VFs: 0, Function Dependency Link: 00
VF offset: 1, stride: 1, Device ID: 46d1
Supported Page Size: 00000553, System Page Size: 00000001
Region 0: Memory at 00000060e0000000 (64-bit, non-prefetchable)
Region 2: Memory at 0000006000000000 (64-bit, prefetchable)
VF Migration: offset: 00000000, BIR: 0
Kernel driver in use: pciback

Now the VMs don't start at all.

vm.start
{
"id": "6783fdf9-3569-0224-fdc0-0082323305fe",
"bypassMacAddressesCheck": false,
"force": false
}
{
"code": "INTERNAL_ERROR",
"params": [
"xenopsd internal error: Cannot_add(0000:00:02.0, Device_common.QMP_Error(5, "{\"error\":{\"class\":\"GenericError\",\"desc\":\"failed to find romfile \\\"/root/vbios.bin\\\"\",\"data\":{}},\"id\":\"qmp-000015-5\"}"))"
],
"call": {
"duration": 4031,
"method": "VM.start",
"params": [
"* session id *",
"OpaqueRef:2877507a-7ad9-f1e6-2b9c-e5690cb21e76",
false,
false
]
},
"message": "INTERNAL_ERROR(xenopsd internal error: Cannot_add(0000:00:02.0, Device_common.QMP_Error(5, "{\"error\":{\"class\":\"GenericError\",\"desc\":\"failed to find romfile \\\"/root/vbios.bin\\\"\",\"data\":{}},\"id\":\"qmp-000015-5\"}")))",
"name": "XapiError",
"stack": "XapiError: INTERNAL_ERROR(xenopsd internal error: Cannot_add(0000:00:02.0, Device_common.QMP_Error(5, "{\"error\":{\"class\":\"GenericError\",\"desc\":\"failed to find romfile \\\"/root/vbios.bin\\\"\",\"data\":{}},\"id\":\"qmp-000015-5\"}")))
at XapiError.wrap (file:///opt/xo/xo-builds/xen-orchestra-202610080923/packages/xen-api/_XapiError.mjs:16:12)
at file:///opt/xo/xo-builds/xen-orchestra-202610080923/packages/xen-api/transports/json-rpc.mjs:38:21
at runNextTicks (node:internal/process/task_queues:65:5)
at processImmediate (node:internal/timers:541:9)"
}

]]>https://xcp-ng.org/forum/post/108943https://xcp-ng.org/forum/post/108943Thu, 08 Oct 2026 08:48:13 GMT<![CDATA[Reply to iGPU PCI passthrough: new experimental packages need testers on Thu, 08 Oct 2026 08:41:07 GMT]]>

@ovicz a dit:

intel alder lake cpu

Thanks for giving this a try!
Can you give me the output of lspci -n -vvv -s SBDF_OF_GPU on your dom0 please?

]]>https://xcp-ng.org/forum/post/108942https://xcp-ng.org/forum/post/108942Thu, 08 Oct 2026 08:41:07 GMT<![CDATA[Reply to iGPU PCI passthrough: new experimental packages need testers on Thu, 08 Oct 2026 08:39:25 GMT]]>Hi. I only have this after acpidump -b on a igpu from intel alder lake cpu.

ls -l | grep dat
-rw-r--r-- 1 root root 476 Oct 8 11:35 apic.dat
-rw-r--r-- 1 root root 92 Oct 8 11:35 dbg2.dat
-rw-r--r-- 1 root root 52 Oct 8 11:35 dbgp.dat
-rw-r--r-- 1 root root 480216 Oct 8 11:35 dsdt.dat
-rw-r--r-- 1 root root 276 Oct 8 11:35 facp.dat
-rw-r--r-- 1 root root 64 Oct 8 11:35 facs.dat
-rw-r--r-- 1 root root 156 Oct 8 11:35 fidt.dat
-rw-r--r-- 1 root root 68 Oct 8 11:35 fpdt.dat
-rw-r--r-- 1 root root 56 Oct 8 11:35 hpet.dat
-rw-r--r-- 1 root root 204 Oct 8 11:35 lpit.dat
-rw-r--r-- 1 root root 60 Oct 8 11:35 mcfg.dat
-rw-r--r-- 1 root root 45 Oct 8 11:35 nhlt.dat
-rw-r--r-- 1 root root 1553 Oct 8 11:35 phat.dat
-rw-r--r-- 1 root root 136 Oct 8 11:35 rmad.dat
-rw-r--r-- 1 root root 1850 Oct 8 11:35 ssdt10.dat
-rw-r--r-- 1 root root 15082 Oct 8 11:35 ssdt11.dat
-rw-r--r-- 1 root root 14810 Oct 8 11:35 ssdt12.dat
-rw-r--r-- 1 root root 324 Oct 8 11:35 ssdt13.dat
-rw-r--r-- 1 root root 916 Oct 8 11:35 ssdt14.dat
-rw-r--r-- 1 root root 419 Oct 8 11:35 ssdt15.dat
-rw-r--r-- 1 root root 427 Oct 8 11:35 ssdt16.dat
-rw-r--r-- 1 root root 7087 Oct 8 11:35 ssdt17.dat
-rw-r--r-- 1 root root 4937 Oct 8 11:35 ssdt18.dat
-rw-r--r-- 1 root root 4027 Oct 8 11:35 ssdt19.dat
-rw-r--r-- 1 root root 908 Oct 8 11:35 ssdt1.dat
-rw-r--r-- 1 root root 23819 Oct 8 11:35 ssdt2.dat
-rw-r--r-- 1 root root 10549 Oct 8 11:35 ssdt3.dat
-rw-r--r-- 1 root root 13271 Oct 8 11:35 ssdt4.dat
-rw-r--r-- 1 root root 54407 Oct 8 11:35 ssdt5.dat
-rw-r--r-- 1 root root 7962 Oct 8 11:35 ssdt6.dat
-rw-r--r-- 1 root root 10883 Oct 8 11:35 ssdt7.dat
-rw-r--r-- 1 root root 9047 Oct 8 11:35 ssdt8.dat
-rw-r--r-- 1 root root 6425 Oct 8 11:35 ssdt9.dat
-rw-r--r-- 1 root root 76 Oct 8 11:35 tpm2.dat
-rw-r--r-- 1 root root 72 Oct 8 11:35 uefi.dat
-rw-r--r-- 1 root root 40 Oct 8 11:35 wsmt.dat

And the python script throws an error :

python3 -c 'import struct,sys;d=open(sys.argv[1],"rb").read();assert d[:4]==b"VFCT",d[:4];n=struct.unpack("<I",d[4:8])[0];off=struct.unpack("<I",d[0x34:0x38])[0];i=0
while off and off+28<=n:
pcibus,pcidev,pcifunc,vendor,device,ssvid,ssid,rev,imagelen=struct.unpack("<IIIHHHHII",d[off:off+28])
if imagelen==0 or off+28+imagelen>n:break
fn="vbios_%02d_%04x_%04x.bin"%(i,vendor,device);open(fn,"wb").write(d[off+28:off+28+imagelen]);print(fn,"bus=%d dev=%d func=%d vid=%04x did=%04x len=%d"%(pcibus,pcidev,pcifunc,vendor,device,imagelen));off+=28+imagelen;i+=1' vfct.dat
Traceback (most recent call last):
File "<string>", line 1, in <module>
FileNotFoundError: [Errno 2] No such file or directory: 'vfct.dat'

]]>https://xcp-ng.org/forum/post/108941https://xcp-ng.org/forum/post/108941Thu, 08 Oct 2026 08:39:25 GMT