[PATCH v2] arm64: Support hard limit of cpu count by nr_cpus

[Suzuki K Poulose]

On 08/08/16 12:28, Kefeng Wang wrote:
>
>
> On 2016/8/8 18:50, Suzuki K Poulose wrote:
>> On 08/08/16 07:05, Kefeng Wang wrote:
>>> Enable the hard limit of cpu count by set boot options nr_cpus=x
>>> on arm64, and show a better warning when cpu number exceeds the limit.
>>>
>>> Reported-by: Shiyuan Hu <hushiyuan at huawei.com>
>>> Signed-off-by: Kefeng Wang <wangkefeng.wang at huawei.com>
>>> ---
>>>
>>> Changed since v1:
>>> - clip cpu number in smp_init_cpus suggested-by Will and Suzuki, and update
>>>   the warning.
>>>
>>>  arch/arm64/kernel/smp.c | 8 ++++----
>>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
>>> index 76a6d92..cbfc31c 100644
>>> --- a/arch/arm64/kernel/smp.c
>>> +++ b/arch/arm64/kernel/smp.c
>>> @@ -661,9 +661,9 @@ void __init smp_init_cpus(void)
>>>          acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT,
>>>                        acpi_parse_gic_cpu_interface, 0);
>>>
>>> -    if (cpu_count > NR_CPUS)
>>> -        pr_warn("no. of cores (%d) greater than configured maximum of %d - clipping\n",
>>> -            cpu_count, NR_CPUS);
>>> +    if (cpu_count > nr_cpu_ids)
>>> +        pr_warn("%d cores exceeds configured maximum of %d - clipping\n",
>>> +            cpu_count, nr_cpu_ids);
>>
>> I think we should leave the message as it was, and is better than what you have
>> changed it to.
>
> The old message is OF only and the old logic shows message when the first cpu number greater than NR_CPUS.

I think you misunderstood "of" (as in plain english) with OF (as in Open Firmware). To avoid
the confusion, how about making it :

"Number of cores (%d) exceeds configured maximum of %d - clipping\n" ?

Certainly a message like :

"5 cores exceeds configured maximum of %d..." doesn't look nice.


Suzuki

> But now the cpu_count is the total cpu counts(get from DT or ACPI), so I change the message.
>
>
>>
>>
>> With that change,
>>
>> Reviewed-by: Suzuki K Poulose <suzuki.poulose at arm.com>
>>
>>
>> .
>>
>