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[PULL v3 03/18] acpi: cpuhp: spec: clarify 'CPU selector' register usage
From: |
Michael S. Tsirkin |
Subject: |
[PULL v3 03/18] acpi: cpuhp: spec: clarify 'CPU selector' register usage and endianness |
Date: |
Thu, 23 Jan 2020 02:10:14 -0500 |
From: Igor Mammedov <address@hidden>
* Move reserved registers to the top of the section, so reader would be
aware of effects when reading registers description.
* State registers endianness explicitly at the beginning of the section
* Describe registers behavior in case of 'CPU selector' register contains
value that doesn't point to a possible CPU.
Signed-off-by: Igor Mammedov <address@hidden>
Reviewed-by: Laszlo Ersek <address@hidden>
Message-Id: <address@hidden>
Reviewed-by: Michael S. Tsirkin <address@hidden>
Signed-off-by: Michael S. Tsirkin <address@hidden>
---
docs/specs/acpi_cpu_hotplug.txt | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/docs/specs/acpi_cpu_hotplug.txt b/docs/specs/acpi_cpu_hotplug.txt
index ee219c8358..4e65286ff5 100644
--- a/docs/specs/acpi_cpu_hotplug.txt
+++ b/docs/specs/acpi_cpu_hotplug.txt
@@ -30,6 +30,18 @@ Register block base address:
Register block size:
ACPI_CPU_HOTPLUG_REG_LEN = 12
+All accesses to registers described below, imply little-endian byte order.
+
+Reserved resisters behavior:
+ - write accesses are ignored
+ - read accesses return all bits set to 0.
+
+The last stored value in 'CPU selector' must refer to a possible CPU, otherwise
+ - reads from any register return 0
+ - writes to any other register are ignored until valid value is stored into
it
+On QEMU start, 'CPU selector' is initialized to a valid value, on reset it
+keeps the current value.
+
read access:
offset:
[0x0-0x3] reserved
@@ -86,9 +98,3 @@ write access:
ACPI_DEVICE_OST QMP event from QEMU to external applications
with current values of OST event and status registers.
other values: reserved
-
-Selecting CPU device beyond possible range has no effect on platform:
- - write accesses to CPU hot-plug registers not documented above are
- ignored
- - read accesses to CPU hot-plug registers not documented above return
- all bits set to 0.
--
MST
- [PULL v3 00/18] virtio, pc: fixes, features, Michael S. Tsirkin, 2020/01/23
- [PULL v3 01/18] q35: implement 128K SMRAM at default SMBASE address, Michael S. Tsirkin, 2020/01/23
- [PULL v3 03/18] acpi: cpuhp: spec: clarify 'CPU selector' register usage and endianness,
Michael S. Tsirkin <=
- [PULL v3 02/18] tests: q35: MCH: add default SMBASE SMRAM lock test, Michael S. Tsirkin, 2020/01/23
- [PULL v3 04/18] acpi: cpuhp: spec: fix 'Command data' description, Michael S. Tsirkin, 2020/01/23
- [PULL v3 05/18] acpi: cpuhp: spec: clarify store into 'Command data' when 'Command field' == 0, Michael S. Tsirkin, 2020/01/23
- [PULL v3 06/18] acpi: cpuhp: introduce 'Command data 2' field, Michael S. Tsirkin, 2020/01/23
- [PULL v3 07/18] acpi: cpuhp: spec: add typical usecases, Michael S. Tsirkin, 2020/01/23
- [PULL v3 09/18] bios-tables-test: document expected file update, Michael S. Tsirkin, 2020/01/23
- [PULL v3 10/18] virtio-9p-device: fix memleak in virtio_9p_device_unrealize, Michael S. Tsirkin, 2020/01/23
- [PULL v3 11/18] virtio-9p-device: convert to new virtio_delete_queue, Michael S. Tsirkin, 2020/01/23
- [PULL v3 12/18] virtio-scsi: delete vqs in unrealize to avoid memleaks, Michael S. Tsirkin, 2020/01/23
- [PULL v3 13/18] virtio-scsi: convert to new virtio_delete_queue, Michael S. Tsirkin, 2020/01/23