linux-kernel - Re: AGP aperture size detection 32b vs. 64b kernels

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Date:	Mon, 23 Feb 2009 09:47:07 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Jeffrey Trull <jetrull@...global.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: AGP aperture size detection 32b vs. 64b kernels


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

>  drivers/char/agp/amd64-agp.c |   13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> Index: linux-2.6/drivers/char/agp/amd64-agp.c
> ===================================================================
> --- linux-2.6.orig/drivers/char/agp/amd64-agp.c
> +++ linux-2.6/drivers/char/agp/amd64-agp.c
> @@ -271,15 +271,15 @@ static __devinit int fix_northbridge(str
>  	nb_order = (nb_order >> 1) & 7;
>  	pci_read_config_dword(nb, AMD64_GARTAPERTUREBASE, &nb_base);
>  	nb_aper = nb_base << 25;
> -	if (agp_aperture_valid(nb_aper, (32*1024*1024)<<nb_order)) {
> -		return 0;
> -	}
>  
>  	/* Northbridge seems to contain crap. Try the AGP bridge. */
>  
>  	pci_read_config_word(agp, cap+0x14, &apsize);
> -	if (apsize == 0xffff)
> +	if (apsize == 0xffff) {
> +		if (agp_aperture_valid(nb_aper, (32*1024*1024)<<nb_order))
> +			return 0;
>  		return -1;
> +	}
>  
>  	apsize &= 0xfff;
>  	/* Some BIOS use weird encodings not in the AGPv3 table. */
> @@ -301,6 +301,11 @@ static __devinit int fix_northbridge(str
>  		order = nb_order;
>  	}
>  
> +	if (nb_order >= order) {
> +		if (agp_aperture_valid(nb_aper, (32*1024*1024)<<nb_order))
> +			return 0;
> +	}
> +

if the fix does the trick then please do some cleanups as well: 
for example the 32MB magic constant should go into a define.

	Ingo
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