In previous commits, several changes were made to IGD passthrough:
* Legacy mode now requires the IGD to be Gen6–Gen9.
* OpRegion quirk is enabled by default.
* "etc/igd-bdsm-size" is set to 0 when guest firmware does not need to
allocate Data Stolen Memory and write BDSM register.
Update the documentation to reflect these changes.
Signed-off-by: Tomita Moeko <tomitamo...@gmail.com>
---
docs/igd-assign.txt | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/docs/igd-assign.txt b/docs/igd-assign.txt
index 3aed7956d5..eac31ea3dd 100644
--- a/docs/igd-assign.txt
+++ b/docs/igd-assign.txt
@@ -47,6 +47,7 @@ Intel document [1] shows how to dump VBIOS to file. For UEFI
Option ROM, see
QEMU also provides a "Legacy" mode that implicitly enables full functionality
on IGD, it is automatically enabled when
+* IGD generation is 6 to 9 (Sandy Bridge to Comet Lake)
* Machine type is i440fx
* IGD is assigned to guest BDF 00:02.0
* ROM BAR or romfile is present
@@ -101,7 +102,7 @@ digital formats work well.
Options
=======
-* x-igd-opregion=[on|*off*]
+* x-igd-opregion=[*on*|off]
Copy host IGD OpRegion and expose it to guest with fw_cfg
* x-igd-lpc=[on|*off*]
@@ -123,7 +124,7 @@ Examples
* Adding IGD with OpRegion and LPC ID hack, but without VGA ranges
(For UEFI guests)
- -device
vfio-pci,host=00:02.0,id=hostdev0,addr=2.0,x-igd-legacy-mode=off,x-igd-opregion=on,x-igd-lpc=on,romfile=efi_oprom.rom
+ -device
vfio-pci,host=00:02.0,id=hostdev0,addr=2.0,x-igd-legacy-mode=off,x-igd-lpc=on,romfile=efi_oprom.rom
Guest firmware
@@ -156,6 +157,12 @@ fw_cfg requirements on the VM firmware:
it's expected that this fw_cfg file is only relevant to a single PCI
class VGA device with Intel vendor ID, appearing at PCI bus address 00:02.0.
+ Starting from Meteor Lake, IGD devices access stolen memory via its MMIO
+ BAR2 (LMEMBAR) and removed the BDSM register in config space. There is
+ no need for guest firmware to allocate data stolen memory in guest address
+ space and write it to BDSM register. Value of this fw_cfg file is 0 in
+ such case.
+
Upstream Seabios has OpRegion and BDSM (pre-Gen11 device only) support.
However, the support is not accepted by upstream EDK2/OVMF. A recommended
solution is to create a virtual OpRom with following DXE drivers:
--
2.47.2
