[Qemu-devel] Re: [PATCH 22/32] add next_cpu_index

[Jan Kiszka]

Glauber Costa wrote:
> On Thu, Oct 23, 2008 at 09:21:45AM -0500, Anthony Liguori wrote:
>> Glauber Costa wrote:
>>> From: Glauber Costa <address@hidden>
>>>
>>> separate the logic for calculating the next cpu index
>>> from cpu creation. It will allow others to query what's
>>> the next cpu index to be created before cpu creation.
>>>   
>> What is this useful for?
> In earlier versions of the series, I was passing the cpu_index to init_env.
> So I guess it's just a die hard patch that survived the reworks. It can be 
> dropped
> now (although I believe its clearer this way).

Why not keep track of the last assigned cpu_index in a global or static
variable? That should be clearer and avoids the iteration (which is
basically a count-how-many-cpus-we-already-have loop).

Jan

> 
>> Regards,
>>
>> Anthony Liguori
>>
>>> Signed-off-by: Glauber Costa <address@hidden>
>>> ---
>>>  exec.c |   22 ++++++++++++++--------
>>>  1 files changed, 14 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/exec.c b/exec.c
>>> index 80b8a78..7fe7eeb 100644
>>> --- a/exec.c
>>> +++ b/exec.c
>>> @@ -526,25 +526,31 @@ static int cpu_common_load(QEMUFile *f, void *opaque, 
>>> int version_id)
>>>  }
>>>  #endif
>>>
>>> -void cpu_exec_init(CPUState *env)
>>> +int next_cpu_index(void)
>>>  {
>>>      CPUState **penv;
>>> -    int cpu_index;
>>> +    int cpu_index = 0;
>>>
>>> -    env->next_cpu = NULL;
>>>      penv = &first_cpu;
>>> -    cpu_index = 0;
>>> +
>>>      while (*penv != NULL) {
>>>          penv = (CPUState **)&(*penv)->next_cpu;
>>>          cpu_index++;
>>>      }
>>> -    env->cpu_index = cpu_index;
>>> +    return cpu_index;
>>> +}
>>> +
>>> +void cpu_exec_init(CPUState *env)
>>> +{
>>> +    env->next_cpu = NULL;
>>> +    env->cpu_index = next_cpu_index();
>>>      env->nb_watchpoints = 0;
>>> -    *penv = env;
>>> +    if (env->cpu_index == 0)
>>> +        first_cpu = env;
>>>  #if defined(CPU_SAVE_VERSION) && !defined(CONFIG_USER_ONLY)
>>> -    register_savevm("cpu_common", cpu_index, CPU_COMMON_SAVE_VERSION,
>>> +    register_savevm("cpu_common", env->cpu_index, CPU_COMMON_SAVE_VERSION,
>>>                      cpu_common_save, cpu_common_load, env);
>>> -    register_savevm("cpu", cpu_index, CPU_SAVE_VERSION,
>>> +    register_savevm("cpu", env->cpu_index, CPU_SAVE_VERSION,
>>>                      cpu_save, cpu_load, env);
>>>  #endif
>>>  }
>>>   


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