"Steven M. Bellovin" <smb@cs.columbia.edu> writes:
>>On the current (old style) install CDs, not directly (you need to put
>>the kernel onto a floppy or disk-on-key or something) because the El
>>Torrito boot mechanism uses a disk image on the CD as the boot
>>medium. (It is not particularly hard to copy one of the kernels into
>>an FFS on a disk-on-key or what have you, but it isn't just a matter
>>of typing the name at the prompt.)
>
> But I thought that the floppy emulation image was boot-big.fs, not the 
> actual kernel.  Certainly, that's the operand to -b in the mkisofs 
> invocation.  That's the program that should be able to deal with a 
> prompt.

The floppy image is just the install kernel + a boot loader on a tarfs
file system. (tarfs is basically just a tar file dd'ed onto the disk
except there is an 8k header in the front with the boot loader in it
-- that's taken from /usr/mdec/bootxx_ustarfs.)

The way this works is the INSTALL kernel has the root file system
embedded inside it in an array. It is rigged up to mount that file
system on boot, so the boot floppy basically just has to supply the
kernel. You can even get an install kernel (and part of the boot code)
out of the boot floppy just by using tar -x.

The shell script that assembles the INSTALL kernel is largely
contained in the Makefile src/distrib/common/Makefile.tarfloppy

We probably should create some shell scripts to make it easier for
non-experts to deal with this stuff, though now that there are
disk-on-key setups, you really don't need to worry about ustarfs any
more, since you can just create a bootable disk-on-key (to make a disk
on key bootable you need to put an MBR on it, disklabel it, newfs it
and installboot it) with the appropriate INSTALL kernel on it.

Perry