linux-kernel - Re: More E820 brokenness

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Message-ID: <20070927235427.GA18900@cosmic.amd.com>
Date:	Thu, 27 Sep 2007 17:54:27 -0600
From:	"Jordan Crouse" <jordan.crouse@....com>
To:	"H. Peter Anvin" <hpa@...or.com>
cc:	jkeating@...hat.com, "Joerg Pommnitz" <pommnitz@...oo.com>,
	"Chuck Ebbert" <cebbert@...hat.com>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
	"Andi Kleen" <ak@...e.de>
Subject: Re: More E820 brokenness

On 27/09/07 16:36 -0700, H. Peter Anvin wrote:
> Jordan Crouse wrote:
> >>>
> >> Oh bugger, looks like this one might be genuinely my fault after all.
> >> The ID check in the new code is buggy.
> >>
> >> Can you please test this revised patch out (against current -git)?
> > 
> > 
> > That looks the same as the previous patch you sent?
> > 
> 
> Sorry, this is the right one...
> 
> 	-hpa

> diff --git a/arch/i386/boot/memory.c b/arch/i386/boot/memory.c
> index bccaa1c..2f37568 100644
> --- a/arch/i386/boot/memory.c
> +++ b/arch/i386/boot/memory.c
> @@ -28,11 +28,10 @@ static int detect_memory_e820(void)
>  
>  	do {
>  		size = sizeof(struct e820entry);
> -		id = SMAP;
>  		asm("int $0x15; setc %0"
> -		    : "=am" (err), "+b" (next), "+d" (id), "+c" (size),
> +		    : "=dm" (err), "+b" (next), "=a" (id), "+c" (size),
>  		      "=m" (*desc)
> -		    : "D" (desc), "a" (0xe820));
> +		    : "D" (desc), "d" (SMAP), "a" (0xe820));
>  
>  		/* Some BIOSes stop returning SMAP in the middle of
>  		   the search loop.  We don't know exactly how the BIOS

Worked, but that just raises more questions.  Why didn't more x86 boxes
break or, alternatively, why did a new version of the BIOS fix the problem? 
I guess we shouldn't look a gift horse in the mouth. Or something.

Thanks very much for your help.

Jordan

-- 
Jordan Crouse
Systems Software Development Engineer 
Advanced Micro Devices, Inc.


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