linux-kernel - Re: [PATCH v8 06/13] x86/apic: Mark the apic_intr

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Date:   Wed, 6 Sep 2017 13:41:26 +0800
From:   Dou Liyang <douly.fnst@...fujitsu.com>
To:     Baoquan He <bhe@...hat.com>
CC:     <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
        <tglx@...utronix.de>, <mingo@...nel.org>, <hpa@...or.com>,
        <rjw@...ysocki.net>, <bp@...en8.de>, <indou.takao@...fujitsu.com>,
        <izumi.taku@...fujitsu.com>
Subject: Re: [PATCH v8 06/13] x86/apic: Mark the apic_intr_mode extern for
 sanity check cleanup

Hi Baoquan,

At 09/06/2017 01:26 PM, Baoquan He wrote:
[...]
>>>  static void __init smp_cpu_index_default(void)
>>> @@ -1335,19 +1295,20 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
>>
>> Please also cleanup the passed in max_cpus since it's not used here any
>> more. And up to the caller:
>
> Oops, I just checked x86 code, other arch also have this hook. Please
> ingore this comment.
>

Yes, you are right.

As I also found the comments for native_smp_prepare_cpus() is out of
date. I will update the comment and explain it like:

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 4f63afc..9f8479c 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1260,8 +1260,10 @@ static void __init smp_get_logical_apicid(void)
  }

  /*
- * Prepare for SMP bootup.  The MP table or ACPI has been read
- * earlier.  Just do some sanity checking here and enable APIC mode.
+ * Prepare for SMP bootup.
+ *
+ * @max_cpus: configured maximum number of CPUs
+ * It don't be used, but other arch also have this hook, so keep it.
   */
  void __init native_smp_prepare_cpus(unsigned int max_cpus)
  {

Thanks,
	dou.
>>
>> static noinline void __init kernel_init_freeable(void)
>> {
>> 	...
>> 	smp_prepare_cpus(setup_max_cpus);
>> 	...
>> }
>>
>>>
>>>  	apic_intr_mode_init();
>>>
>>> -	switch (smp_sanity_check(max_cpus)) {
>>> -	case SMP_NO_CONFIG:
>>> -		disable_smp();
>>> -		return;
>>> -	case SMP_NO_APIC:
>>> +	smp_sanity_check();
>>> +
>>> +	switch (apic_intr_mode) {
>>> +	case APIC_PIC:
>>> +	case APIC_VIRTUAL_WIRE_NO_CONFIG:
>>>  		disable_smp();
>>>  		return;
>>> -	case SMP_FORCE_UP:
>>> +	case APIC_SYMMETRIC_IO_NO_ROUTING:
>>>  		disable_smp();
>>>  		/* Setup local timer */
>>>  		x86_init.timers.setup_percpu_clockev();
>>>  		return;
>>> -	case SMP_OK:
>>> +	case APIC_VIRTUAL_WIRE:
>>> +	case APIC_SYMMETRIC_IO:
>>>  		break;
>>>  	}
>>>
>>> --
>>> 2.5.5
>>>
>>>
>>>
>
>
>