On Tue, 2025-04-22 at 00:31 +0800, Tomita Moeko wrote: > CAUTION: External Email!! > 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:
Not sure how upstream prefers handling documentation. Those are only small changes, so I'd add them to the corresponding commits. -- Kind regards, Corvin
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