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Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c

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On 01/12/15 16:31, Mark Rutland wrote:
> For PSCI 0.2+ we can query AFFINITY_INFO to discover whether a CPU is
> whether or not it is in the firmware (i.e. whether or not it is
> potentially in the kernel), so we can certainly query this in some
> cases.
>
> We already do this in the usual hotplug-off case; see cpu_kill.

OK, good to know.

>> Correct, I didn't think about kexec. May be we could indicate the result
>> back (that we are looping in kernel) in secondary_data and that could solve
>> the synchronisation part ?
>
> I think we need to have two flags, a cpu-must-die flag in secondary
> data, and a global stuck-in-the-kernel flag.
>
> The CPU wanting to die could set its cpu-must-die flag, signal the
> completion, then cpu_die(). The CPU awaiting the completion would then
> check cpu-must-die, and if so, cpu_kill() that CPU. If not set, we had a
> successful onlining.

Correct.

>
> We need stuck-in-the-kernel flag to account for CPUs which didn't manage
> to turn the MMU on (which are either in the spin-table, or failed when
> they were individually onlined).

Did you mean to say "turn the MMU off" ?

Cheers
Suzuki

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[PATCH v2 0/6] arm64: cpufeature: Add sanity check for ASIDBits "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100
  [PATCH v2 4/6] arm64: Add hook for checking early CPU features "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100
  [PATCH v2 1/6] arm64: Introduce kill_cpu_early "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100
  [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100
    Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c Mark Rutland <mark.rutland@arm.com> - 2015-12-01 16:30 +0100
      Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-12-01 17:10 +0100
        Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c Mark Rutland <mark.rutland@arm.com> - 2015-12-01 17:40 +0100
          Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-12-01 18:40 +0100
            Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c Mark Rutland <mark.rutland@arm.com> - 2015-12-01 19:00 +0100
              Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-12-01 19:20 +0100
                Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c Mark Rutland <mark.rutland@arm.com> - 2015-12-01 20:00 +0100
                Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-12-03 17:40 +0100
                Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c Mark Rutland <mark.rutland@arm.com> - 2015-12-03 18:10 +0100
  [PATCH v2 6/6] arm64: Ensure the secondary CPUs have safe ASIDBits size "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100
  [PATCH v2 5/6] arm64: Add helper for extracting ASIDBits "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100

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