On Sun, May 04, 2025 at 06:45:59PM +0200, Krzysztof Kozlowski wrote: > On Sat, May 03, 2025 at 12:15:06PM GMT, Ricardo Neri wrote: > > Add bindings for CPUs in x86 architecture. Start by defining the `reg` and > > What for?
Thank you for your quick feedback, Krzysztof! Do you mean for what reason I want to start bindings for x86 CPUs? Or only the `reg` property? If the former, it is to add an enable-method property to x86 CPUs. If the latter, is to show the relationship between APIC and `reg`. > > > `enable-method` properties and their relationship to x86 APIC ID and the > > available mechanisms to boot secondary CPUs. > > > > Start defining bindings for Intel processors. Bindings for other vendors > > can be added later as needed. > > > > Signed-off-by: Ricardo Neri <ricardo.neri-calde...@linux.intel.com> > > --- > > Not really tested so only limited review follows. Sorry, I ran make dt_binding_check but only on this schema. I missed the reported error. > > > .../devicetree/bindings/x86/cpus.yaml | 80 +++++++++++++++++++ > > 1 file changed, 80 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/x86/cpus.yaml > > > > diff --git a/Documentation/devicetree/bindings/x86/cpus.yaml > > b/Documentation/devicetree/bindings/x86/cpus.yaml > > new file mode 100644 > > index 000000000000..108b3ad64aea > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/x86/cpus.yaml > > @@ -0,0 +1,80 @@ > > +# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/x86/cpus.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: x86 CPUs > > + > > +maintainers: > > + - Ricardo Neri <ricardo.neri-calde...@linux.intel.com> > > + > > +description: | > > + Description of x86 CPUs in a system through the "cpus" node. > > + > > + Detailed information about the CPU architecture can be found in the Intel > > + Software Developer's Manual: > > + https://intel.com/sdm > > + > > +properties: > > + compatible: > > + enum: > > + - intel,x86 > > That's architecture, not a CPU. CPUs are like 80286, 80386, so that's > not even specific instruction set. I don't get what you need it for. Am I to understand the the `compatible` property is not needed if the bindings apply to any x86 CPU? > > > + > > + reg: > > Missing constraints. I could add minItems. For maxItems, there is no limit to the number of threads. > > > + description: | > > Do not need '|' unless you need to preserve formatting. OK. > > > + Local APIC ID of the CPU. If the CPU has more than one execution > > thread, > > + then the property is an array with one element per thread. > > + > > + enable-method: > > + $ref: /schemas/types.yaml#/definitions/string > > + description: | > > + The method used to wake up secondary CPUs. This property is not > > needed if > > + the secondary processors are booted using INIT assert, de-assert > > followed > > + by Start-Up IPI messages as described in the Volume 3, Section 11.4 > > of > > + Intel Software Developer's Manual. > > + > > + It is also optional for the bootstrap CPU. > > + > > + oneOf: > > I see only one entry, so didn't you want an enum? Indeed, enum would be more appropriate. > > > + - items: > > Not a list > > > + - const: intel,wakeup-mailbox > > So every vendor is supposed to come with different name for the same > feature? Or is wakeup-mailnox really intel specific, but then specific > to which processors? It would not be necessary for every vendor to provide a different name for the same feature. I saw, however that the Devicetree specification requires a [vendor],[method] stringlist. Also, platform firmware for any processor could implement the wakeup mailbox. > > > > + description: | > > + CPUs are woken up using the mailbox mechanism. The platform > > + firmware boots the secondary CPUs and puts them in a state > > + to check the mailbox for a wakeup command from the operating > > + system. > > + > > +required: > > + - reg > > + - compatible > > + > > +unevaluatedProperties: false > > Missing ref in top-level or this is supposed to be additionalProps. See > example-schema. I will check. > > > + > > +examples: > > + - | > > + /* > > + * A system with two CPUs. cpu@0 is the bootstrap CPU and its status is > > + * "okay". It does not have the enable-method property. cpu@1 is a > > + * secondary CPU. Its status is "disabled" and defines the > > enable-method > > + * property. > > + */ > > + > > + cpus { > > + #address-cells = <1>; > > + #size-cells = <0>; > > + > > + cpu@0 { > > + reg = <0x0 0x1>; > > + compatible = "intel,x86"; > > + status = "okay"; > > Drop I will drop status = "okay" > > > + }; > > + > > + cpu@1 { > > + reg = <0x0 0x1>; > > + compatible = "intel,x86"; > > + status = "disabled"; > > Why? Because this is a secondary CPU that the operating system will enable using the method specified in the `enable-method` property. Thanks and BR, Ricardo
