| Date | Tue, 09 Sep 2014 00:23:25 -0400 | From | Jon Masters <> | Subject | Re: [PATCH v3 09/17] ARM64 / ACPI: Parse MADT for SMP initialization |
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On 09/01/2014 10:57 AM, Hanjun Guo wrote: > MADT contains the information for MPIDR which is essential for > SMP initialization, parse the GIC cpu interface structures to > get the MPIDR value and map it to cpu_logical_map(), and add > enabled cpu with valid MPIDR into cpu_possible_map. > > ACPI 5.1 only has two explicit methods to boot up SMP, PSCI and > Parking protocol, but the Parking protocol is only specified for > ARMv7 now, so make PSCI as the only way for the SMP boot protocol > before some updates for the ACPI spec or the Parking protocol spec.
> + /* CPU 0 was already initialized */ > + if (cpu) { > + if (cpu_ops[cpu]->cpu_init(NULL, cpu)) > + return -EOPNOTSUPP; > + > + /* map the logical cpu id to cpu MPIDR */ > + cpu_logical_map(cpu) = mpidr;
I'm not sure it's worth noting in a comment or just in the dialogue that none of these MPIDR values is literally the value in the MPIDR. Linux doesn't store that anyway (even in the cpu_logical_map), since it is pre-filtered against MPIDR_HWID_BITMASK to remove the non-affinity level bits. And since the ACPI5.1 specification requires that non-affinity bits be zero everything works. But it relies upon this assumption so it might be worth explicitly masking out the bits when making the call into:
acpi_map_gic_cpu_interface(processor->arm_mpidr, processor->flags & ACPI_MADT_ENABLED);
During the parsing of the processor object's MPIDR value.
Jon.
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