On Wed, 07 Jan 2026 13:44:39 -0800, Ricardo Neri wrote: > Add DeviceTree bindings to enumerate the wakeup mailbox used in platform > firmware for Intel processors. > > x86 platforms commonly boot secondary CPUs using an INIT assert, de-assert > followed by Start-Up IPI messages. The wakeup mailbox can be used when this > mechanism is unavailable. > > The wakeup mailbox offers more control to the operating system to boot > secondary CPUs than a spin-table. It allows the reuse of the same wakeup > vector for all CPUs while maintaining control over which CPUs to boot and > when. While it is possible to achieve the same level of control using a > spin-table, it would require specifying a separate `cpu-release-addr` for > each secondary CPU. > > The operation and structure of the mailbox are described in the > Multiprocessor Wakeup Structure defined in the ACPI specification. Note > that this structure does not specify how to publish the mailbox to the > operating system (ACPI-based platform firmware uses a separate table). No > ACPI table is needed in DeviceTree-based firmware to enumerate the mailbox. > > Nodes that want to refer to the reserved memory usually define > a `memory-region` property. /cpus/cpu* nodes would want to refer to the > mailbox, but they do not have such property defined in the DeviceTree > specification. Moreover, it would imply that there is a memory region per > CPU. Instead, add a `compatible` property that the operating system can use > to discover the mailbox. > > Reviewed-by: Dexuan Cui <[email protected]> > Reviewed-by: Rob Herring (Arm) <[email protected]> > Acked-by: Rafael J. Wysocki (Intel) <[email protected]> > Co-developed-by: Yunhong Jiang <[email protected]> > Signed-off-by: Yunhong Jiang <[email protected]> > Signed-off-by: Ricardo Neri <[email protected]> > --- > Changes in v8: > - None > > Changes in v7: > - Fixed Acked-by tag from Rafael to include the "(Intel)" suffix. > > Changes in v6: > - Reworded the changelog for clarity. > - Added Acked-by tag from Rafael. Thanks! > - Added Reviewed-by tag from Rob. Thanks! > - Added Reviewed-by tag from Dexuan. Thanks! > > Changes in v5: > - Specified the version and section of the ACPI spec in which the > wakeup mailbox is defined. (Rafael) > - Fixed a warning from yamllint about line lengths of URLs. > > Changes in v4: > - Removed redefinitions of the mailbox and instead referred to ACPI > specification as per discussion on LKML. > - Clarified that DeviceTree-based firmware do not require the use of > ACPI tables to enumerate the mailbox. (Rob) > - Described the need of using a `compatible` property. > - Dropped the `alignment` property. (Krzysztof, Rafael) > - Used a real address for the mailbox node. (Krzysztof) > > Changes in v3: > - Implemented the mailbox as a reserved-memory node. Add to it a > `compatible` property. (Krzysztof) > - Explained the relationship between the mailbox and the `enable-mehod` > property of the CPU nodes. > - Expanded the documentation of the binding. > > Changes in v2: > - Added more details to the description of the binding. > - Added requirement a new requirement for cpu@N nodes to add an > `enable-method`. > --- > .../reserved-memory/intel,wakeup-mailbox.yaml | 50 > ++++++++++++++++++++++ > 1 file changed, 50 insertions(+) >
My bot found errors running 'make dt_binding_check' on your patch: yamllint warnings/errors: ./Documentation/devicetree/bindings/reserved-memory/intel,wakeup-mailbox.yaml:23:1: [warning] too many blank lines (2 > 1) (empty-lines) dtschema/dtc warnings/errors: doc reference errors (make refcheckdocs): See https://patchwork.kernel.org/project/devicetree/patch/[email protected] The base for the series is generally the latest rc1. A different dependency should be noted in *this* patch. If you already ran 'make dt_binding_check' and didn't see the above error(s), then make sure 'yamllint' is installed and dt-schema is up to date: pip3 install dtschema --upgrade Please check and re-submit after running the above command yourself. Note that DT_SCHEMA_FILES can be set to your schema file to speed up checking your schema. However, it must be unset to test all examples with your schema.
