Re: [PATCH for-5.0 3/8] acpi: cpuhp: spec: clarify 'CPU selector' register usage and endianness
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 > --- > 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. > Reviewed-by: Laszlo Ersek
[PATCH for-5.0 3/8] acpi: cpuhp: spec: clarify 'CPU selector' register usage and endianness
* 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 --- 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
