Hi Vitaly, adding Igor, Michael, Marcel, and qemu-devel.
On 07/20/20 11:06, vit9696 wrote: > Hello, > > I discovered an issue with inconsistent QEMU/OVMF device paths, and > while I am unsure whether directing this e-mail is appropriate to you, > I believe that you likely have the contacts you could forward this > e-mail to. > > macOS uses ACPI UIDs to build the DevicePath for NVRAM boot options, > while OVMF firmware gets them via an internal channel through QEMU. > Due to a bug in QEMU (or OVMF) currently UEFI firmware and ACPI have > different values, and this makes the underlying operating system > unable to report its boot option. > > The particular node in question is the primary PciRoot (PCI0 in ACPI), > which for some reason gets assigned 1 in ACPI UID and 0 in the > DevicePath. To me this looks like a bug here: > https://github.com/qemu/qemu/blob/8f06f22/hw/i386/acpi-build.c#L1511-L1515 > Which does not correspond to the primary PCI identifier here: > https://github.com/qemu/qemu/blob/5a79d10/hw/pci/pci.c#L160-L162 > > Reference with the device paths, OVMF startup logs, and ACPI table > dumps (SysReport): > https://github.com/acidanthera/bugtracker/issues/1050 > > Would you be able to forward this to the right people or perhaps keep > an eye on the issue itself? I think you are right. In UEFI v2.8, section "10.4.2 Rules with ACPI _HID and _UID" ends with the paragraph, Root PCI bridges will use the plug and play ID of PNP0A03, This will be stored in the ACPI Device Path _HID field, or in the Expanded ACPI Device Path _CID field to match the ACPI name space. The _UID in the ACPI Device Path structure must match the _UID in the ACPI name space. (See especially the last sentence.) Considering *extra* root bridges / root buses (with bus number > 0), QEMU's ACPI generator actually does the right thing; since QEMU commit c96d9286a6d7 ("i386/acpi-build: more traditional _UID and _HID for PXB root buses", 2015-06-11). However, the _UID values for root bridge zero (on both i440fx and q35) have always been "wrong" (from UEFI perspective), going back in QEMU to commit 74523b850189 ("i386: add ACPI table files from seabios", 2013-10-14). Even in SeaBIOS, these _UID values have always been 1; see commit a4d357638c57 ("Port rombios32 code from bochs-bios.", 2008-03-08) for i440fx, and commit ecbe3fd61511 ("seabios: q35: add dsdt", 2012-12-01) for q35. Does the following patch work for you? (I can see you proposed the same in <https://github.com/acidanthera/bugtracker/issues/1050#issuecomment-660734139>) > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c > index b7bcbbbb2a35..7a5a8b3521b0 100644 > --- a/hw/i386/acpi-build.c > +++ b/hw/i386/acpi-build.c > @@ -1496,9 +1496,9 @@ build_dsdt(GArray *table_data, BIOSLinker *linker, > sb_scope = aml_scope("_SB"); > dev = aml_device("PCI0"); > aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A03"))); > aml_append(dev, aml_name_decl("_ADR", aml_int(0))); > - aml_append(dev, aml_name_decl("_UID", aml_int(1))); > + aml_append(dev, aml_name_decl("_UID", aml_int(0))); > aml_append(sb_scope, dev); > aml_append(dsdt, sb_scope); > > build_hpet_aml(dsdt); > @@ -1511,9 +1511,9 @@ build_dsdt(GArray *table_data, BIOSLinker *linker, > dev = aml_device("PCI0"); > aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A08"))); > aml_append(dev, aml_name_decl("_CID", aml_eisaid("PNP0A03"))); > aml_append(dev, aml_name_decl("_ADR", aml_int(0))); > - aml_append(dev, aml_name_decl("_UID", aml_int(1))); > + aml_append(dev, aml_name_decl("_UID", aml_int(0))); > aml_append(dev, build_q35_osc_method()); > aml_append(sb_scope, dev); > aml_append(dsdt, sb_scope); If it does, I suggest submitting the above patch to qemu-devel, and/or filing a bug for upstream QEMU at <https://bugs.launchpad.net/qemu/>. (Note: I didn't even compile the above change.) Thanks Laszlo
