Hi,

> 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;
> 		}
> 	}

result:

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: at arch/x86/kernel/cpu/mtrr/generic.c:405
generic_get_mtrr+0xd0/0x10a()
[    0.000000] mtrr: your BIOS has set up an incorrect mask.
[    0.000000] Modules linked in:
[    0.000000] Pid: 0, comm: swapper Not tainted 2.6.28.4-ibm #1
[    0.000000] Call Trace:
[    0.000000]  [<ffffffff8023acca>] warn_slowpath+0xb4/0xda
[    0.000000]  [<ffffffff8023b8c6>] vprintk+0x2a4/0x2d1
[    0.000000]  [<ffffffff80221bea>] default_spin_lock_flags+0x6/0x8
[    0.000000]  [<ffffffff80451cf9>] printk+0x4e/0x5d
[    0.000000]  [<ffffffff80453e6a>] _spin_lock_irqsave+0x25/0x2c
[    0.000000]  [<ffffffff802194c0>] mtrr_wrmsr+0x1b/0x48
[    0.000000]  [<ffffffff805e5f88>] get_mtrr_state+0x2e5/0x2f1
[    0.000000]  [<ffffffff8021960e>] generic_get_mtrr+0xd0/0x10a
[    0.000000]  [<ffffffff805e4e0d>] mtrr_bp_init+0x1f5/0xc39
[    0.000000]  [<ffffffff805e58e4>]
mtrr_trim_uncached_memory+0x93/0x374
[    0.000000]  [<ffffffff805f07c9>] early_iounmap+0x13d/0x19d
[    0.000000]  [<ffffffff805f07c9>] early_iounmap+0x13d/0x19d
[    0.000000]  [<ffffffff805da140>] early_idt_handler+0x0/0x71
[    0.000000]  [<ffffffff805e0d56>] setup_arch+0x407/0x78c
[    0.000000]  [<ffffffff805f4c81>] cgroup_init_subsys+0x2a/0xd9
[    0.000000]  [<ffffffff805f4f5e>] cgroup_init_early+0x1a4/0x1b6
[    0.000000]  [<ffffffff80453f10>] _spin_lock+0x6/0x7
[    0.000000]  [<ffffffff805da931>] start_kernel+0x7b/0x38b
[    0.000000]  [<ffffffff805da140>] early_idt_handler+0x0/0x71
[    0.000000]  [<ffffffff805da3a1>] x86_64_start_kernel+0xe7/0xf4
[    0.000000] ---[ end trace 4eaa2a86a8e2da22 ]---



-----Original Message-----
From: Yinghai Lu [mailto:yinghai@kernel.org] 
Sent: Tuesday, February 10, 2009 3:40 AM
To: Ingo Molnar
Cc: Morten P.D. Stevens; Thomas Gleixner; H. Peter Anvin; Arjan van de
Ven; linux-kernel@vger.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@win-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;
 		}
 	}