Messages in this thread | | | Date | Thu, 23 Sep 2021 12:48:13 +0300 | From | Nick Kossifidis <> | Subject | Re: [PATCH] riscv: Add RISC-V svpbmt extension |
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Στις 2021-09-23 12:42, Nick Kossifidis έγραψε: > Στις 2021-09-23 12:37, Anup Patel έγραψε: >> On Thu, Sep 23, 2021 at 2:55 PM Nick Kossifidis <mick@ics.forth.gr> >> wrote: >>> >>> Hello Guo, >>> >>> Στις 2021-09-23 10:27, guoren@kernel.org έγραψε: >>> diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml >>> b/Documentation/devicetree/bindings/riscv/cpus.yaml >>> index e534f6a7cfa1..1825cd8db0de 100644 >>> --- a/Documentation/devicetree/bindings/riscv/cpus.yaml >>> +++ b/Documentation/devicetree/bindings/riscv/cpus.yaml >>> @@ -56,7 +56,9 @@ properties: >>> enum: >>> - riscv,sv32 >>> - riscv,sv39 >>> + - riscv,sv39,svpbmt >>> - riscv,sv48 >>> + - riscv,sv48,svpbmt >>> - riscv,none >>> >>> Isn't svpbmt orthogonal to the mmu type ? It's a functionality that >>> can >>> be present on either sv39/48/57 so why not have another "svpbmt" >>> property directly on the cpu node ? >> >> Actually, "mmu-type" would be a good place because it's page based >> memory attribute and paging can't exist without mmu translation mode. >> >> Also, "svpmbt" is indeed a CPU property so has to be feature >> individual >> CPU node. Hypothetically, a heterogeneous system is possible where >> some CPUs have "svpmbt" and some CPUs don't have "svpmbt". For >> example, a future FUxxx SoC might have a E-core and few S-cores >> where S-cores have Svpmbt whereas E-core does not have Svpmbt >> because it's an embedded core. >> > > I should say cpuX node, not the root /cpu node. We can have an svpbmt > property in the same way we have an mmu-type property. >
I'm also thinking of future mmu-related extensions, e.g. what about svnapot ? Should we have mmu-type be riscv,sv39,svnapot and e.g. riscv.sv39,svpbmt,svnapot ? It'll become messy.
Regards, Nick
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