AW: More E820 brokenness

From: Joerg Pommnitz
Date: Fri Sep 28 2007 - 02:19:54 EST

Hello all,
I won't be able to test anything before next Tuesday, but I'm with
Jordan on this one. Have a look at the dmsg output I sent you some
time ago (

This was as plain from Linus' tree as you get it (git bisect, make defconfig, make)
and I see:
BIOS-provided physical RAM map:
BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved)
BIOS-e820: 0000000000100000 - 000000001e7b0000 (usable)
BIOS-e820: 000000001e7b0000 - 000000001e7bffc0 (ACPI data)
BIOS-e820: 000000001e7bffc0 - 000000001e7c0000 (ACPI NVS)
BIOS-e820: 0000000040400000 - 0000000040440004 (reserved)
BIOS-e820: 00000000f0000000 - 0000000100000000 (reserved) --
Kind regards


----- Ursprüngliche Mail ----
Von: Jordan Crouse <jordan.crouse@xxxxxxx>
An: H. Peter Anvin <hpa@xxxxxxxxx>
CC: jkeating@xxxxxxxxxx; Joerg Pommnitz <pommnitz@xxxxxxxxx>; Chuck Ebbert <cebbert@xxxxxxxxxx>; Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; Andi Kleen <ak@xxxxxxx>
Gesendet: Freitag, den 28. September 2007, 01:15:52 Uhr
Betreff: Re: More E820 brokenness

On 27/09/07 15:47 -0700, H. Peter Anvin wrote:
> Jordan Crouse wrote:
> >
> > Breaks on the Geode - original behavior.
> >
> > I think that having boot_prams.e820_entries != 0 makes the kernel
> > assume the e820 data is correct.
> >
> Okay, now I'm utterly baffled how 2.6.22 ever worked on this Geode,
> because this, to the best of my reading, mimics the 2.6.22 behavior
> exactly. DID IT REALLY, and/or did you make any kind of configuration
> changes?

I copied in a 2.6.22 kernel to see that it really did work, and it did.
But here's the crazy part - I did a dmesg, and it looks like it
*is* using e820 data, and it looks complete (I see the entire map -
including the ACPI and reserved blocks way up high).

So apparently it was the 2.6.22 code that was buggy, but reading it,
I don't immediately see how.

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

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