Hi Suzuki,
On 06/04/16 12:24, Suzuki K Poulose wrote:
> maxcpu=n sets the number of CPUs activated at boot time to a max of n,
> but allowing the remaining CPUs to be brought up later if the user
> decides to do so. However, on arm64 due to various reasons, we disallowed
> hotplugging CPUs beyond n, by marking them not present. Now that
> we have checks in place to make sure the hotplugged CPUs have compatible
> features with system and requires no new errata, relax the restriction.
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index b2d5f4e..0988ccc 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -659,21 +659,12 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> if (max_cpus > ncores)
> max_cpus = ncores;
This "if (max_cpus > ncores)" is the only user of max_cpus left in this
function, and 'ncores' isn't used for anything else. Dead code?
> - /* Don't bother if we're effectively UP */
> - if (max_cpus <= 1)
> - return;
> -
> /*
> * Initialise the present map (which describes the set of CPUs
> * actually populated at the present time) and release the
> * secondaries from the bootloader.
> - *
> - * Make sure we online at most (max_cpus - 1) additional CPUs.
> */
> - max_cpus--;
> for_each_possible_cpu(cpu) {
> - if (max_cpus == 0)
> - break;
>
> if (cpu == smp_processor_id())
> continue;
> @@ -686,7 +677,6 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> continue;
>
> set_cpu_present(cpu, true);
> - max_cpus--;
> }
> }
>
>
Thanks,
James
