Re: [PATCH] x86_64: not set boot cpu in cpu_online_map at smp_prepare_boot_cpu

[Yinghai Lu <Yinghai.Lu@Sun.COM>]

Zachary Amsden wrote:
> On Mon, 2007-11-26 at 00:38 -0800, Yinghai Lu wrote:
>> [PATCH] x86_64: not set boot cpu in cpu_online_map at smp_prepare_boot_cpu
>>
>> in init/main.c boot_cpu_init() does that before
>>
>> Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
>>
>> diff --git a/arch/x86/kernel/smpboot_64.c b/arch/x86/kernel/smpboot_64.c
>> index 500670c..966d124 100644
>> --- a/arch/x86/kernel/smpboot_64.c
>> +++ b/arch/x86/kernel/smpboot_64.c
>> @@ -912,7 +912,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
>>  void __init smp_prepare_boot_cpu(void)
>>  {
>>  	int me = smp_processor_id();
>> -	cpu_set(me, cpu_online_map);
>> +	/* already set me in cpu_online_map in boot_cpu_init() */
>>  	cpu_set(me, cpu_callout_map);
>>  	per_cpu(cpu_state, me) = CPU_ONLINE;
>>  }
> 
> 
> This ordering can be tricky wrt CPU hotplug.  Are you sure you are not
> breaking CPU hotplug?  AFAIK, x86_64 has that right and the 32-bit code
> had it wrong.


CPU hot plug path will call smp_prepare_boot_cpu?
it is using __init instead of __cpuinit?

YH