Complete Linux/Complete Linux.iso/kernels/old_docs/bootdisk.faq

Text File | 1994-05-29 | 2.6 KB | 70 lines

There's only one question that's *really* frequently asked, and that's
"How do I make a bootdisk with drivers for XXX?"

Well..... here goes. :^)

First, you need to make a new kernel with the drivers you want. You'll have
to apply a small patch first, to make the kernel wait for you to switch in
the rootdisk before attempting to load it into the ramdisk. This patch can be
found on ftp.cdrom.com: /pub/linux/slackware_source/bootdisk/ramdisk.c.
Replace /usr/src/linux/drivers/block/ramdisk.c with this new version. Then,
'make config' and select the drivers you want. Once you've got that figured
out, do 'make dep ; make clean ; make zImage' to build the new kernel.

Modify the bootflags on the kernel, so that it will load a ramdisk:
rdev -R zImage 0
rdev -r zImage 1440 (use 1200 if you're using a 5.25" floppy drive)
rdev -v zImage -1
rdev zImage /dev/fd0

OK, now we are ready to put this kernel on a disk. Make a copy of a bootkernel
disk as a starting point, and then mount it with a command like this:

mount /dev/fd0 /mnt

Put the new kernel in place like this:
cat zImage > /mnt/vmlinuz

And unmount the disk:
umount /dev/fd0

Now the disk must be activated with LILO in order to make it self-booting.
You'll need to use another copy of the kernel to do this. Put a different
formatted (and expendable) disk into /dev/fd0, and do this:

rdev -r zImage 0   (this tells it NOT to use a ramdisk for this)
cat zImage > /dev/fd0

At this point, reboot your machine, leaving the disk in the drive. Your
machine will load the new disk, and it will ask you to insert a disk to
be mounted as root and hit ENTER. At this point, take the disk out and
replace it with the new bootkernel disk and hit ENTER.

You'll see some error messages on your way to the login prompt. You can
ignore them. When you get a login prompt, log in as root.

Now for the magic words:

lilo
sync

After typing 'lilo', you should see 'Added ramdisk' and 'Added mount' appear
at the bottom of the screen. When you get another prompt, you type 'sync'.
As soon as the disk stops spinning and the drive light goes out, take the disk
out of the drive.

That should do it! This new disk should work as a bootkernel disk.

Also - if you already have a kernel image that you want to use, you can use
an image without the ramdisk patch. You still have to do all the 'rdev's to
it. If you do use an unpatched kernel, the bootkernel disk you create will not
prompt for you to insert the rootdisk, but should still work fine. You'll just
have to swap the rootdisk in once you see the 'Uncompressing Linux' message.

Good luck!!! :^)

---
Patrick Volkerding
[e-mail]
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