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authorLaszlo Ersek <lersek@redhat.com>2015-06-11 02:37:58 +0200
committerMichael S. Tsirkin <mst@redhat.com>2015-06-11 12:40:30 +0200
commitc96d9286a6d70452e5fa4f1e3f840715e325be95 (patch)
tree007726d10a8a31ebca5b35bd3e374c15e8070c59
parent21549a4642e1f1b438ffc31dd9dc35f134b10e5b (diff)
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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>
-rw-r--r--hw/i386/acpi-build.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index db32fd1..8fae3b9 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) {