Using Linux on BIOS limited to 504MB \ VOGONS

Using Linux on BIOS limited to 504MB

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First post, by eesz34

Posted on 2023-10-25, 13:39

eesz34 Offline

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The BIOS in my 386 allows me to set more than 1024 cylinders, but MSDOS fdisk only recognizes 500MB or so. Not surprising. I don't have a lot of use for more in DOS anyway, but I was thinking, could I put an old Slackware release on it since Linux doesn't use the BIOS handler?

I think what I'd have to do is shrink the DOS partition some so the start of the Linux partition is still within the first 1023 cylinders. But, this assumes the relevant files are within this region until Linux takes over the BIOS routines. Has anyone tried this? It seems feasible, but perhaps tricky. Or, maybe I need to make a small boot partition just at the end of 1023 cylinder limit that boots Linux. Not sure how to do that.

Reply 1 of 5, by BitWrangler

Posted on 2023-10-25, 14:10

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Maybe find some clues here...
https://www.ibiblio.org/pub/Linux/docs/HOWTO/ … arge-Disk-HOWTO
There might be earlier editions of that on pre 1998 distribution disks that have more about the lower limits.

Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.

Reply 2 of 5, by eesz34

Posted on 2023-10-25, 14:22

eesz34 Offline

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BitWrangler wrote on 2023-10-25, 14:10:

Maybe find some clues here...
https://www.ibiblio.org/pub/Linux/docs/HOWTO/ … arge-Disk-HOWTO
There might be earlier editions of that on pre 1998 distribution disks that have more about the lower limits.

Nice, that is precisely what I was looking for.

Reply 3 of 5, by the3dfxdude

Posted on 2023-10-25, 15:01

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If you are saying you have dos on the first primary partition within the 504mb limit, then you can just run loadlin and boot linux from dos. The kernel will load as a file on the dos file system, and you won't need any overlay. You don't need to repartition in a linux partition to move a linux kernel image within the 1024 cylinders, when the kernel is already accessible on your dos partition.

Reply 4 of 5, by eesz34

Posted on 2023-10-25, 16:20

eesz34 Offline

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the3dfxdude wrote on 2023-10-25, 15:01:

If you are saying you have dos on the first primary partition within the 504mb limit, then you can just run loadlin and boot linux from dos. The kernel will load as a file on the dos file system, and you won't need any overlay. You don't need to repartition in a linux partition to move a linux kernel image within the 1024 cylinders, when the kernel is already accessible on your dos partition.

Oh interesting. I seem to recall something about this from awhile back.

Reply 5 of 5, by thp

Posted on 2023-10-25, 17:00

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+1 on loadlin. Works fine here even with the latest kernel (6.5.9), and with a busybox initrd, you can even boot into a minimal Linux system from a DOS partition alone.

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