diff options
| author | Laszlo Ersek <lersek@redhat.com> | 2015-06-11 02:37:58 +0200 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2015-06-11 12:40:30 +0200 |
| commit | c96d9286a6d70452e5fa4f1e3f840715e325be95 (patch) | |
| tree | 007726d10a8a31ebca5b35bd3e374c15e8070c59 /hw | |
| parent | 21549a4642e1f1b438ffc31dd9dc35f134b10e5b (diff) | |
i386/acpi-build: more traditional _UID and _HID for PXB root buses
The ACPI specification permits the _HID and _UID objects to evaluate to
strings. (See "6.1.5 _HID (Hardware ID)" and "6.1.12 _UID (Unique ID)" in
the ACPI v6.0 spec.)
With regard to related standards, the UEFI specification can also express
a device address composed from string _HID and _UID identifiers, inside
the Expanded ACPI Device Path Node. (See "9.3.3 ACPI Device Path", Table
49, in the UEFI v2.5 spec.)
However, numeric (integer) contents for both _HID and _UID are more
traditional. They are recommended by the UEFI spec for size reasons:
[...] the ACPI Device Path node is smaller and should be used if
possible to reduce the size of device paths that may potentially be
stored in nonvolatile storage [...]
External tools support them better (for example the --acpi_hid and
--acpi_uid options of "efibootmgr" only take numeric identifiers).
Finally, numeric _HID and _UID contents are existing practice in the QEMU
source.
This patch was tested with a Fedora 20 LiveCD and a preexistent Windows
Server 2012 R2 guest. Using "acpidump" and "iasl" in the Fedora guest, we
get, in the SSDT:
> Scope (\_SB)
> {
> Device (PC04)
> {
> Name (_UID, 0x04) // _UID: Unique ID
> Name (_HID, EisaId ("PNP0A03") /* PCI Bus */) // _HID: Hardware ID
Cc: Marcel Apfelbaum <marcel@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw')
| -rw-r--r-- | hw/i386/acpi-build.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c index db32fd1526..8fae3b9037 100644 --- a/hw/i386/acpi-build.c +++ b/hw/i386/acpi-build.c @@ -944,9 +944,8 @@ build_ssdt(GArray *table_data, GArray *linker, scope = aml_scope("\\_SB"); dev = aml_device("PC%.02X", bus_num); - aml_append(dev, - aml_name_decl("_UID", aml_string("PC%.02X", bus_num))); - aml_append(dev, aml_name_decl("_HID", aml_string("PNP0A03"))); + aml_append(dev, aml_name_decl("_UID", aml_int(bus_num))); + aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A03"))); aml_append(dev, aml_name_decl("_BBN", aml_int(bus_num))); if (numa_node != NUMA_NODE_UNASSIGNED) { |