[syslinux] ISOLinux and OpenBSD?

Murali Krishnan Ganapathy gmurali at cs.uchicago.edu
Wed Mar 17 07:47:02 PST 2004

I am now in the process of getting an ISOLinux based CD to boot into 
OpenBSD. Is there anybody who has already done this? I seem to have hit 
upon a few problems.

* Since the OpenBSD kernel is very different from the Linux Kernel (in 
particular it contains the ramdisk image within it), I guess ISOLinux 
cannot boot the kernel?
* So the only way to boot OpenBSD is to make a 2.88MB (or 1.44MB) floppy 
image, and boot it through memdisk?

ftp://ftp.openbsd.org/pub/openbsd/3.4/i386/ has all the images I am 
talking about. In particular floppy34.fs and cd34.fs are 1.44 and 2.88MB 
floppy images, and cd34.iso is an iso image (wrapper around cd34.fs, 
which does not use ISOLinux).
What I have seen so far....

+ booting floppy34.fs image from the CD works correctly (no ISOLinux, in 
built BIOS emulates the floppy)
+ presumably booting cd34.iso off a CD also works (openBSD people would 
surely have ensured that)
+ booting cd34.fs through memdisk doesn't work (I changed the extension 
+ Yet to try floppy34.fs through memdisk.

booting cd34.fs through memdisk: memdisk loads fine and passes control 
to the boot sector of the floppy image. This inturn passes control to 
"boot" (openbsd bootloader). This checks all the peripherals (and 
reports them) fine. Then it displays "fd0" and hangs there. Doing a "man 
boot" on an OpenBSD machine, suggests that boot at this point is trying 
to read the file "/etc/boot.conf" on the floppy image.

Since cd34.fs (when packaged in cd34.iso) works, we can assume that all 
disk accesses happen through the BIOS and not directly to the 
controller. So, this should be something specific between ISOLinux and 
the OpenBSD floppy image? I think I can rule out the BIOS / Motherboard, 
bcos I have booted DOS floppy images using memdisk on that machine 
without any problems.

Any ideas?

- Murali

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