Re: [UPDATED PATCH 21/27] sparc32, smpboot: Use generic SMP bootinginfrastructure

[Srivatsa S. Bhat]

On 06/02/2012 01:14 PM, Sam Ravnborg wrote:

> On Sat, Jun 02, 2012 at 08:52:49AM +0200, Sam Ravnborg wrote:
>> Hi Srivatsa.
>>
>> I cannot see how this would work for sparc32...
>> [Did not notice before...]
>>
>>> --- a/arch/sparc/kernel/leon_smp.c
>>> +++ b/arch/sparc/kernel/leon_smp.c
>>
>>> +void __cpuinit __cpu_pre_starting(void *unused)
>>> +{
>>> +	unsigned int cpuid = hard_smp_processor_id();
>>>  
>>> diff --git a/arch/sparc/kernel/sun4d_smp.c b/arch/sparc/kernel/sun4d_smp.c
>>> index ddaea31..cd5367a 100644
>>> --- a/arch/sparc/kernel/sun4d_smp.c
>>> +++ b/arch/sparc/kernel/sun4d_smp.c
>>
>>> +void __cpuinit __cpu_pre_starting(void *unused)
>>> +{
>>> +	unsigned int cpuid = hard_smp_processor_id();
>>>  
>>> diff --git a/arch/sparc/kernel/sun4m_smp.c b/arch/sparc/kernel/sun4m_smp.c
>>> index 128af73..ed05f54 100644
>>> --- a/arch/sparc/kernel/sun4m_smp.c
>>> +++ b/arch/sparc/kernel/sun4m_smp.c
>>
>>> +void __cpuinit __cpu_pre_starting(void *unused)
>>> +{
>>> +	unsigned int cpuid = hard_smp_processor_id();
>>
>> See how you define a function with the same name three times.
>> On sparc32 we include all of the above files in the kernel,
>> and uses various tricks to determine at run-time
>> which variant to use.
>>
>> We need to define these general functions in smp_32.c and
>> then take relevant action depending on sparc_cpu_model.
> 
> I took a short look at this.
> And it is a bit complicated :-(
> 
> leon is the odd-one here. For reasons I do not understand
> we have a call from head_32.S to leon_smp_cpu_startup:
> in trampoline_32.S.
> 
> But sun4m and sun4d uses the normal path via start_kernel() etc.
> 
> This has the side-effect that sparc_cpu_model is not set
> when we call leon_smp_cpu_startup.
> 


Yes, I saw that too now..

> I will try to dive into this and see if I on the sparc32 side
> can make leon behave like the other platforms, and then 
> unify some of the smp cpu boot stuff such that we then
> can introduce the generalization from your patch.
> 


Thanks a lot for that Sam!
 
Regards,
Srivatsa S. Bhat

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