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:	Wed, 11 Feb 2009 11:43:32 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Yinghai Lu <yinghai@...nel.org>
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


* Yinghai Lu <yinghai@...nel.org> wrote:

> 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;
>  		}
>  	}

Could you please embedd this info in the WARN_ONCE() itself please, so that it gets 
reported as one unit? (and send a proper changelogged patch, etc.) WARN_ONCE() is a 
full printk as well so you can add anything to it.

Thanks,

	Ingo
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