On 24/12/2023 00:20, Alexander Graf wrote: >>> new file mode 100644 >>> index 000000000000..9960fefc292d >>> --- /dev/null >>> +++ b/Documentation/devicetree/bindings/kho/ftrace/ftrace-array.yaml >>> @@ -0,0 +1,46 @@ >>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) >>> +%YAML 1.2 >>> +--- >>> +$id: http://devicetree.org/schemas/kho/ftrace/ftrace-array.yaml# >>> +$schema: http://devicetree.org/meta-schemas/core.yaml# >>> + >>> +title: Ftrace trace array >>> + >> Missing description. Commit msg also does not tell me much. This must >> stand on its own and must describe the hardware. Whatever you have in >> cover letter, does not matter, especially that you did not Cc us on it. > > > Alrighty, I'll add descriptions and make the commit message stand on its > own. > > For quick reference: KHO is a new mechanism this patch set introduces > which allows Linux to pass arbitrary memory and metadata between kernels > on kexec. I'm reusing FDTs to implement the hand over protocol, as > Linux-to-Linux boot communication holds very similar properties to > firmware-to-Linux boot communication. So this binding is not about > hardware; it's about preserving Linux subsystem state across kexec. Devicetree is for non-discoverable systems and their hardware, not for passing arbitrary data between kernels. For me this does not suit DT at all, please use other ways. > > For more details, please refer to the KHO documentation which is part of > patch 7 of this patch set: > https://lore.kernel.org/lkml/20231222195144.24532-2-graf@xxxxxxxxxx/ > > >> >>> +maintainers: >>> + - Alexander Graf <graf@xxxxxxxxxx> >>> + >>> +properties: >>> + compatible: >>> + enum: >>> + - ftrace,array-v1 >>> + >>> + trace_flags: >> Underscores are not allowed. Does not look like generic property. > > > Let me make it "trace-flags" to not have underscores. Could you please > elaborate on what you mean by generic property? Generic property, so one without vendor prefix, is shared and common to a group of devices. > > >> >> >>> + $ref: /schemas/types.yaml#/definitions/uint32 >>> + description: >>> + Bitmap of all the trace flags that were enabled in the trace array at the >>> + point of serialization. >>> + >>> +# Subnodes will be of type "ftrace,cpu-v1", one each per CPU >>> +additionalProperties: true >> No, this must be false. And it goes after required: > > > Ok, making it false and adding pattern matches instead for subnodes. > > >> >> >>> + >>> +required: >>> + - compatible >>> + - trace_flags >>> + >>> +examples: >>> + - | >>> + ftrace { >>> + compatible = "ftrace-v1"; >>> + events = <1 1 2 2 3 3>; >>> + >>> + global_trace { >> Again, no underscores. > > > Ok :) > > >> >>> + compatible = "ftrace,array-v1"; >>> + trace_flags = < 0x3354601 >; >>> + >>> + cpu0 { >>> + compatible = "ftrace,cpu-v1"; >>> + cpu = < 0x00 >; >> Drop redundant spaces. > > > I don't understand what you're referring to as redundant spaces? Double > checking, I believe indentation is off for every line below "ftrace {". > Is that what you're referring to? Fixing :) Open DTS, some recent, arm64 like Qualcomm. Do you see spaces around <>? Or open the coding style document... Please do not introduce different coding style. > > >> >>> + mem = < 0x101000000ULL 0x38ULL 0x101000100ULL 0x1000ULL 0x101000038ULL 0x38ULL 0x101002000ULL 0x1000ULL>; >> ? Do you see any of such syntax in DTS? > > > I was trying to make it easy to reason to readers about 64bit numbers - 64bit numbers are not a problem for DTS reading. Above syntax is. > and then potentially extend dtc to consume that new syntax. KHO DTs are > native/little endian, so dtc already has some difficulties interpreting > it which I'll need to fix up with patches to it eventually :). I'll > change it to something that looks more 32bit'y for now. > Best regards, Krzysztof
