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

[Kefeng Wang]

On 2016/8/8 20:52, Suzuki K Poulose wrote:
> 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" ?

Er, I do misunderstood it, my bad, will use this one, thanks :)

Kefeng
> 
> 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>
>>>
>>>
>>> .
>>>
>>
> 
> 
> .
>