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Re: [PATCH 1/2] i386/acpi: fix inconsistent QEMU/OVMF device paths
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH 1/2] i386/acpi: fix inconsistent QEMU/OVMF device paths |
Date: |
Thu, 30 Jul 2020 18:11:17 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 |
On 7/30/20 5:58 PM, Michael S. Tsirkin wrote:
> 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 ACPI 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. This is due to the _UID assigned to it by build_dsdt in
> hw/i386/acpi-build.c Which does not correspond to the primary PCI
> identifier given by pcibus_num in hw/pci/pci.c
>
> Reference with the device paths, OVMF startup logs, and ACPI table
> dumps (SysReport):
> https://github.com/acidanthera/bugtracker/issues/1050
>
> 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.
>
> Suggested-by: Laszlo Ersek <lersek@redhat.com>
> Tested-by: vit9696 <vit9696@protonmail.com>
Vitaly uses his full name on EDK2 mailing list, so I don't think he'll
have a problem to use it in QEMU too:
Tested-by: Vitaly Cheptsov <vit9696@protonmail.com>
From:
https://wiki.qemu.org/Contribute/SubmitAPatch#Patch_emails_must_include_a_Signed-off-by:_line
"Please use your real name to sign a patch (not an alias or acronym)."
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
> hw/i386/acpi-build.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index b7bcbbbb2a..7a5a8b3521 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1497,7 +1497,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> 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);
>
> @@ -1512,7 +1512,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> 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);
>