On 30/01/14 17:21, Ian Campbell wrote: > On Thu, 2014-01-30 at 17:13 +0000, Marc Zyngier wrote: >> Hi Ian, >> >> On 30/01/14 16:11, Ian Campbell wrote: >>> mach-virt has existed for a while but it is not written down what it actually >>> consists of. Although it seems a bit unusual to document a binding for an >>> entire platform since mach-virt is entirely virtual it is helpful to have >>> something to refer to in the absence of a single concrete implementation. >>> >>> I've done my best to capture the requirements based on the git log and my >>> memory/understanding. >>> >>> While here remove the xenvm dts example, the Xen tools will now build a >>> suitable mach-virt compatible dts when launching the guest. >>> >>> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx> >>> Cc: Rob Herring <robh+dt@xxxxxxxxxx> >>> Cc: Pawel Moll <pawel.moll@xxxxxxx> >>> Cc: Mark Rutland <mark.rutland@xxxxxxx> >>> Cc: Kumar Gala <galak@xxxxxxxxxxxxxx> >>> Cc: Olof Johansson <olof@xxxxxxxxx> >>> Cc: Arnd Bergmann <arnd@xxxxxxxx> >>> Cc: Marc Zyngier <marc.zyngier@xxxxxxx> >>> Cc: Will Deacon <will.deacon@xxxxxxx> >>> Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> >>> Cc: devicetree@xxxxxxxxxxxxxxx >>> Cc: linux-kernel@xxxxxxxxxxxxxxx >>> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx >>> --- >>> I'm not sure which tree this sort of thing should go though, sorry for the >>> huge Cc. >>> --- >>> .../devicetree/bindings/arm/mach-virt.txt | 32 ++++++++ >>> arch/arm/boot/dts/xenvm-4.2.dts | 81 -------------------- >>> 2 files changed, 32 insertions(+), 81 deletions(-) >>> create mode 100644 Documentation/devicetree/bindings/arm/mach-virt.txt >>> delete mode 100644 arch/arm/boot/dts/xenvm-4.2.dts >>> >>> diff --git a/Documentation/devicetree/bindings/arm/mach-virt.txt b/Documentation/devicetree/bindings/arm/mach-virt.txt >>> new file mode 100644 >>> index 0000000..562bcda >>> --- /dev/null >>> +++ b/Documentation/devicetree/bindings/arm/mach-virt.txt >>> @@ -0,0 +1,32 @@ >>> +* Mach-virt "Dummy Virtual Machine" platform >>> + >>> +"mach-virt" is the smallest, dumbest platform possible, to be used as >>> +a guest for Xen, KVM and other hypervisors. It has no >>> +properties/functionality of its own and is driven entirely by device >>> +tree. >>> + >>> +This document defines the requirements for such a platform. >>> + >>> +* Required properties: >>> + >>> +- compatible: should be one of: >>> + "linux,dummy-virt" >>> + "xen,xenvm" >>> + >>> +In addition to the standard nodes (chosen, cpus, memory etc) the >>> +platform is required to provide certain other basic functionality >>> +which must be described in the device tree: >>> + >>> + The platform must provide an ARM Generic Interrupt Controller >>> + (GIC), defined in Documentation/devicetree/bindings/arm/gic.txt. >>> + >>> + The platform must provide ARM architected timer, defined in >>> + Documentation/devicetree/bindings/arm/arch_timer.txt. >>> + >>> + If the platform is SMP then it must provide the Power State >>> + Coordination Interface (PSCI) described in >>> + Documentation/devicetree/bindings/arm/psci.txt. >> >> I'm afraid I disagree with most of the above. The whole point of >> mach-virt is to provide a shell for DT platforms. None of this hardware >> is mandated. Instead, all the necessary information should be described >> in DT. > > "Add support for the smallest, dumbest possible platform, to be > used as a guest for KVM or other hypervisors. > > It only mandates a GIC and architected timers" > > (your original commit message :-P) Right. 1984, here we come. I'll disappear for a while, rewriting the history. More seriously, that was just me scheming to get it merged, hiding my cunning plan for mach-virt world domination! >> Actually, mach-virt doesn't really stand for Virtual Machine. It stands >> for virtual mach-* directory! Eventually, mach-virt should become the >> default platform, the one we use when we don't match anything else in >> the kernel > > I can word it more like that for sure, along with the alternative > wording suggested by Christopher/Stefano to clarify the intent that > everything comes from DTB and removal of the specific requirements for > GIC/timer/PSCI I think that suit the (new) intention better? Yes, please! :-) M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
