linux-kernel - Re: [patch] x86: 2.6.31-rc7 crash due to buggy flat_phys_pkg

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Date:	Tue, 25 Aug 2009 13:36:41 -0700
From:	Ravikiran G Thirumalai <kiran@...lex86.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Yinghai Lu <yinghai@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Cyrill Gorcunov <gorcunov@...il.com>,
	linux-kernel@...r.kernel.org, shai@...lex86.org,
	Suresh Siddha <suresh.b.siddha@...el.com>
Subject: Re: [patch] x86: 2.6.31-rc7 crash due to buggy flat_phys_pkg_id

On Tue, Aug 25, 2009 at 09:24:16PM +0200, Ingo Molnar wrote:
>> ...
>> > Furthermore, commit 2759c3287 did not declare any side-effects and 
>> > clearly causes a side-effect on vSMP which apparently has an 
>> > overlapping set of initial APIC ids.
>> > 
>> > Ravikiran, your patch does not do a clear revert of this bit though. 
>> > If you do a plain revert of the line above alone, does that fix the 
>> > problem too?
>> 
>> how about patch phys_pkg_id for vsmp?
>> 
>> diff --git a/arch/x86/kernel/apic/probe_64.c b/arch/x86/kernel/apic/probe_64.c
>> index f3b1037..65edc18 100644
>> --- a/arch/x86/kernel/apic/probe_64.c
>> +++ b/arch/x86/kernel/apic/probe_64.c
>> @@ -44,6 +44,11 @@ static struct apic *apic_probe[] __initdata = {
>>  	NULL,
>>  };
>>  
>> +static int apicid_phys_pkg_id(int initial_apic_id, int index_msb)
>> +{
>> +	return hard_smp_processor_id() >> index_msb;
>> +}
>> +
>>  /*
>>   * Check the APIC IDs in bios_cpu_apicid and choose the APIC mode.
>>   */
>> @@ -69,6 +74,11 @@ void __init default_setup_apic_routing(void)
>>  		printk(KERN_INFO "Setting APIC routing to %s\n", apic->name);
>>  	}
>>  
>> +	if (is_vsmp_box()) {
>> +		/* need to update phys_pkg_id */
>> +		apic->phys_pkg_id = apicid_phys_pkg_id;
>> +	}
>
>Hm, this is rather tempting simply because it only affects vSMP 
>systems and we are in late -rc's. Ravikiran, does Yinghai's patch 
>solve the crash for you too?
>

Yes it does.  Tested and confirmed.

Thanks,
Kiran
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