linux-kernel - Re: warning in arch/x86/kernel/cpu/mtrr/generic.c:400 with 2.6.29-rc3 on IBM x3400

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Date:	Mon, 09 Feb 2009 18:40:13 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>
CC:	"Morten P.D. Stevens" <mstevens@...-professional.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Arjan van de Ven <arjan@...radead.org>,
	linux-kernel@...r.kernel.org
Subject: Re: warning in arch/x86/kernel/cpu/mtrr/generic.c:400 with	2.6.29-rc3
 on IBM x3400

Ingo Molnar wrote:
> * Morten P.D. Stevens <mstevens@...-professional.com> wrote:
> 
>> Hi,
>>
>> Update:
>>
>> the same issue with a linux 2.6.28.4 kernel.
>>
>> [    0.000000] ------------[ cut here ]------------
>> [    0.000000] WARNING: at arch/x86/kernel/cpu/mtrr/generic.c:404 generic_get_mtrr+0xdf/0x119()
>> [    0.000000] mtrr: your BIOS has set up an incorrect mask, fixing it up.
> 
> buggy BIOS most likely. Had the kernel not fixed up the MTRRs you'd have
> a very slow and unhappy system now.

please try:
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 0c0a455..7a359ce 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -397,7 +397,8 @@ static void generic_get_mtrr(unsigned int reg, unsigned long *base,
 		tmp |= ~((1<<(hi - 1)) - 1);
 
 		if (tmp != mask_lo) {
-			WARN_ONCE(1, KERN_INFO "mtrr: your BIOS has set up an incorrect mask, fixing it up.\n");
+			printk(KERN_INFO "mtrr: BIOS set mask_lo: %x should be %x, fixing it up\n", mask_lo, tmp);
+			WARN_ONCE(1, KERN_INFO "mtrr: your BIOS has set up an incorrect mask.\n");
 			mask_lo = tmp;
 		}
 	}
--
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