linux-kernel - Re: [PATCH] x86: Don't print number of MCE banks for every CPU

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Date:	Tue, 27 Oct 2009 13:53:13 -0700
From:	Mike Travis <travis@....com>
To:	Roland Dreier <rdreier@...co.com>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	x86@...nel.org
Subject: Re: [PATCH] x86: Don't print number of MCE banks for every CPU


Mike Travis wrote:
> Hi Roland,
> 
> I've found that I'm getting one of these lines for every cpu:
> 
> mce: CPU supports 0 MCE banks
> 

A bit more info.  THe data above was from our simulator which
apparently is not simulating mce very well.  On a live system
I get 383 lines (for 383 additional cpus) with what appears to be
redundant lines...

[    4.882085] CPU 1 MCA banks SHD:0 SHD:1 CMCI:2 CMCI:3 CMCI:5 SHD:6 SHD:7 SHD:8 SHD:9 SHD:12 SHD:13 SHD:14 SHD:15 SHD:16 SHD:17 SHD:18 SHD:19 SHD:20 SHD:21
[    4.978893] CPU 2 MCA banks SHD:0 SHD:1 CMCI:2 CMCI:3 CMCI:5 SHD:6 SHD:7 SHD:8 SHD:9 SHD:12 SHD:13 SHD:14 SHD:15 SHD:16 SHD:17 SHD:18 SHD:19 SHD:20 SHD:21
...
[    4.978893] CPU 2 MCA banks SHD:0 SHD:1 CMCI:2 CMCI:3 CMCI:5 SHD:6 SHD:7 SHD:8 SHD:9 SHD:12 SHD:13 SHD:14 SHD:15 SHD:16 SHD:17 SHD:18 SHD:19 SHD:20 SHD:21


> Regards,
> Mike
> 
> Roland Dreier wrote:
>> The MCE initialization code explicitly says it doesn't handle asymmetric
>> configurations where different CPUs support different numbers of MCE
>> banks, and it prints a big warning in that case.  Therefore, printing
>> the "mce: CPU supports <x> MCE banks" message into the kernel log for
>> every CPU is pure redundancy that clutters the log significantly for
>> systems with lots of CPUs.
>>
>> Signed-off-by: Roland Dreier <rolandd@...co.com>
>> ---
>>  arch/x86/kernel/cpu/mcheck/mce.c |    3 ++-
>>  1 files changed, 2 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/mcheck/mce.c 
>> b/arch/x86/kernel/cpu/mcheck/mce.c
>> index b1598a9..721a77c 100644
>> --- a/arch/x86/kernel/cpu/mcheck/mce.c
>> +++ b/arch/x86/kernel/cpu/mcheck/mce.c
>> @@ -1214,7 +1214,8 @@ static int __cpuinit mce_cap_init(void)
>>      rdmsrl(MSR_IA32_MCG_CAP, cap);
>>  
>>      b = cap & MCG_BANKCNT_MASK;
>> -    printk(KERN_INFO "mce: CPU supports %d MCE banks\n", b);
>> +    if (!banks)
>> +        printk(KERN_INFO "mce: CPU supports %d MCE banks\n", b);
>>  
>>      if (b > MAX_NR_BANKS) {
>>          printk(KERN_WARNING
>> -- 
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