[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[PATCH for-5.0 3/8] acpi: cpuhp: spec: clarify 'CPU selector' register u
From: |
Igor Mammedov |
Subject: |
[PATCH for-5.0 3/8] acpi: cpuhp: spec: clarify 'CPU selector' register usage and endianness |
Date: |
Wed, 4 Dec 2019 18:05:42 +0100 |
* 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>
---
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 ee219c8..4e65286 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.
--
2.7.4
- [PATCH for-5.0 0/8] q35: CPU hotplug with secure boot, part 1+2, Igor Mammedov, 2019/12/04
- [PATCH for-5.0 3/8] acpi: cpuhp: spec: clarify 'CPU selector' register usage and endianness,
Igor Mammedov <=
- [PATCH for-5.0 6/8] acpi: cpuhp: spec: add typical usecases, Igor Mammedov, 2019/12/04
- [PATCH for-5.0 5/8] acpi: cpuhp: spec: clarify store into 'Command data' when 'Command field' == 0, Igor Mammedov, 2019/12/04
- [PATCH for-5.0 7/8] acpi: cpuhp: add CPHP_GET_CPU_ID_CMD command, Igor Mammedov, 2019/12/04
[PATCH for-5.0 8/8] acpi: cpuhp: spec: document procedure for enabling modern CPU hotplug, Igor Mammedov, 2019/12/04