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Re: [PATCH for-5.0 3/8] acpi: cpuhp: spec: clarify 'CPU selector' regist
Re: [PATCH for-5.0 3/8] acpi: cpuhp: spec: clarify 'CPU selector' register usage and endianness
Thu, 5 Dec 2019 12:50:37 +0100
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On 12/04/19 18:05, Igor Mammedov wrote:
> * 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,
> + - 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:
> [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.
Reviewed-by: Laszlo Ersek <address@hidden>
[PATCH for-5.0 8/8] acpi: cpuhp: spec: document procedure for enabling modern CPU hotplug, Igor Mammedov, 2019/12/04
- [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, 2019/12/04
- Re: [PATCH for-5.0 3/8] acpi: cpuhp: spec: clarify 'CPU selector' register usage and endianness,
Laszlo Ersek <=
- [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