How to build boot disk for boot/root floppy

How to build boot disk for boot/root floppy

Post by Scott Mckins » Sat, 06 Aug 1994 14:42:20



I have a problem with probes to my NE2000 clone locking up my computer
(it conflicts with my IN2000 scsi).

The question is how do you build a custom boot disk that will wait for
a disk change to load the root floppy?  Or how about just replacing the
kernel on the slackware boot disk?

Thanks,

Scott

 
 
 

How to build boot disk for boot/root floppy

Post by David A. Bers » Tue, 09 Aug 1994 08:18:05


:> The question is how do you build a custom boot disk that will wait for
:> a disk change to load the root floppy?  Or how about just replacing the
:> kernel on the slackware boot disk?

I have done this for kernel version 1.1.35.  From a brief look at the
kernel, it looks like this should happen.  However, some of the stuff
with ramdisks has changed in the last few versions, so maybe it is broken.

Anyway, in recent kernel versions, there is a function rd_load() in
/usr/src/linux/drivers/block/ramdisk.c.
In this function, after the first if stmt I added the following lines:

printk("Insert root disk and press ENTER\n" );
wait_for_keypress();

To make my boot disk I used dd to copy the slackware image to the harddrive,
and then back to a fresh disk (to preserve the old kernel, just in case)
then I did the following with the new boot disk in /dev/fd0:

mount -t minix /dev/fd0 /mnt
cp zImage /mnt/vmlinuz
cd /mnt
rdev vmlinuz /dev/fd0
ramsize vmlinuz 1440
lilo -r /mnt -C etc/lilo.conf

David A. Berson.


 
 
 

1. Boot + root or boot/root floppies: how??

My root ext2 partition has had a long run, and it finally needs a defrag, so I
want to make boot/root floppies that are capable of running defrag.  (Defrag
fyi doesn't run on a mounted fs).

The Bootdisk.HOWTO is hopelessly outdated (it proudly proclaims support for
kernel 1.2.0!) and was pretty much unhelpful.  I want to hopefully get about 2
megs of stuff on 1 disk, and this seems feasible with compression and the use
of a ramdisk.  I've tried to use yard, Bootkit, CatRescue, etc. to no avail,
although yard seems to be the closest to being able to give me what I want: a
basic filesystem, with my 1.3.79 kernel on it, and e2defrag.  Yard works fine
in building the filesystem in the ramdisk and compressing it, and even succeeds
in dd'ing the compressed kernel and filesystem to disk.  Then it says:
Doing some rdev's...
and after a brief delay a slew of floppy errors beginning with
"floppy0: not current!"
splatter across my screen.  Then yard happily reports "Done." and exits.
When I boot with that floppy the kernel loads, VFS says to put in the root disk
so I just hit return since it's a boot/root disk, and the kernel panics with
something about MSDOS filesystem. (??)  My limited knowledge of boot/root disks
tells me that the problem is one of the rdevs that failed was telling the
kernel where to find the root filesystem on the floppy.  (I could be wrong...)
But I haven't had success in making those rdev's work right, I even tried going
through the perl scripts and doing them roughly by hand.

So, two things: first, does anyone recognize the above floppy error?  (If so
how do I fix it?)  And, am I right and it's the failed rdev's that are the
problem or is something else going on?

One diagnostic: my floppy drive (or possibly the floppy controller) is
sometimes problematic because it can't write to the last two tracks on a disk.
However the first 78 are reliable and I don't think this is related to the
problem because a) I have a set of Slackware boot and root disks which I made
on this floppy drive following the Slackware instructions, that work fine--I
can't use them because they don't have e2defrag or even the libraries necessary
to run e2defrag; b) the compressed filesystem+kernel takes up far less than the
first 78 tracks on the disk, maybe two-thirds of the disk tops.

I think I can do it on 2 disks (although I haven't succeeded yet) but this
compression thing is driving me crazy and I'm determined to do it that way now.

Thx in advance
Cory Dodt

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