Re: Linux 2.2.19pre2

From: Kurt Garloff (garloff@suse.de)
Date: Wed Dec 20 2000 - 05:44:09 EST

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On Wed, Dec 20, 2000 at 12:32:54PM +0200, Petri Kaukasoina wrote:
> OK, I booted 2.4.0-test12 which even prints that list:
>
> BIOS-provided physical RAM map:
> BIOS-e820: 000000000009fc00 @ 0000000000000000 (usable)
> BIOS-e820: 0000000000000400 @ 000000000009fc00 (reserved)
> BIOS-e820: 0000000003480000 @ 0000000000100000 (usable)
> BIOS-e820: 0000000000100000 @ 00000000fec00000 (reserved)
> BIOS-e820: 0000000000100000 @ 00000000fee00000 (reserved)
> BIOS-e820: 0000000000010000 @ 00000000ffff0000 (reserved)
> Memory: 52232k/54784k available (831k kernel code, 2164k reserved, 62k data, 168k init, 0k highmem)
>
> The last three reserved lines correspond to the missing 2.5 Megs. What are
> they?

Data reserved by your system for whatever purpose.
Most probably ACPI data or similar.

> 2.2.18 sees all 56 Megs and works ok and after adding mem=56M on the
> kernel command line even 2.2.19pre2 works ok with all the 56 Megs. No
> crashes.

If you would have ACPI events, you would probably run into trouble.
Apart from this, chances are that the reserved data is not needed by Linux
and never accessed by the BIOS, so you may get away with using the reserved
memory.
The safe way is to respect the BIOS' RAM map.

Regards,

-- Kurt Garloff <garloff@suse.de> Eindhoven, NL GPG key: See mail header, key servers Linux kernel development SuSE GmbH, Nuernberg, FRG SCSI, Security

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