On Sun, Feb 09, 2025 at 04:23:09PM +0100, Krzysztof Kozlowski wrote: > On 09/02/2025 16:10, Mike Rapoport wrote: > > On Sun, Feb 09, 2025 at 11:29:41AM +0100, Krzysztof Kozlowski wrote: > >> On 06/02/2025 14:27, Mike Rapoport wrote: > >>> From: "Mike Rapoport (Microsoft)" <rppt@xxxxxxxxxx> > >>> > >>> We introduced KHO into Linux: A framework that allows Linux to pass > >>> metadata and memory across kexec from Linux to Linux. KHO reuses fdt > >>> as file format and shares a lot of the same properties of firmware-to- > >>> Linux boot formats: It needs a stable, documented ABI that allows for > >>> forward and backward compatibility as well as versioning. > >> > >> Please use subject prefixes matching the subsystem. You can get them for > >> example with `git log --oneline -- DIRECTORY_OR_FILE` on the directory > >> your patch is touching. For bindings, the preferred subjects are > >> explained here: > >> https://www.kernel.org/doc/html/latest/devicetree/bindings/submitting-patches.html#i-for-patch-submitters > > > > These are not devicetree binding for communicating data from firmware to > > the kernel. These bindings are specific to KHO which is perfectly > > reflected by the subject. > > No, it is not. None of the bindings use above subject prefix. > > > > > Just a brief reminder from v2 discussion: > > (https://lore.kernel.org/linux-mm/20231222193607.15474-1-graf@xxxxxxxxxx/) > > > > "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. > > does not matter. You added file to ABI documentation so you must follow > that ABI documentation rules. One rule is proper subject prefix. No, it does not. It's a different ABI. FDT is a _data structure_ that provides cross platform unified, versioned, introspectable data format. Documentation/devicetree/bindings standardizes it's use for describing hardware, but KHO uses FDT _data structure_ to describe state of the kernel components that will be reused by the kexec'ed kernel. KHO is a different namespace from Open Firmware Device Tree, with different requirements and different stakeholders. Putting descriptions of KHO data formats in Documentation/kho rather than in Documentation/devicetree/bindings was not done to evade review of Open Firmware Device Tree maintainers, but rather to emphasize that KHO FDT _is not_ Open Firmware Device Tree. > Best regards, > Krzysztof -- Sincerely yours, Mike.
