Subject: Re: booting from an alternate partition?
To: Markus Illenseer <>
From: David Laight <>
List: current-users
Date: 07/19/2002 23:28:59
>  Well, it can read the kernel from FFS. Would it be possible to change the
> loader to load the kernel from other partitions and other file systems?
> I.e. CD9660?

Theoretically yes, but the loader has to have its own copy of the code
that understands the file system format.  Also it does rely on the PC
BIOS for the disk read/write functions - and I don't know if there
are ones for ATAPI CDROMs [1].
The other slight problem is that without major surgery the boot
program is limited to 64k for its code, data and stack (but not heap).
Some code I added earlier in the week (to do filename globbing in 'ls')
caused the stack to hit the data area.  So adding support for another
file system type could be problematical.

>  I am not sure how the "read a command" would help? This command, where is
> it? And what can the command do w/o a kernel?

A command like 'boot -s'

Oh yes, boot supports -q (quiet) and -v (verbose) on all ports and
passes the value into the kernel....


[1] bootable CDROM for PCs have a file that contains a floppy image!

David Laight: