grub floppy fails to boot
I'm repeating a question for which I still lack an answer.
The object is to boot a new installation of debian sarge, filesystem
reiserfs, from a grub (0.95+cvs20040624-8) boot loader installed on a
diskette. Grub has not yet been installed on the target disk because I
want the security of a boot floppy in case it gums things up when I do
install it (I assume that a grub boot floppy does not need to have
grub installed on the hard disk).
This diskette boots my current system (debian sarge, reiserfs) just
fine. And the bootloader on my current disk (sda) MBR can boot the
target disk (sdc). It's only using the boot floopy to boot the target
disk that I get into trouble.
At this point I'm trying to understand the set of boot error messages
associated with a kernel panic when try to use it to boot the target
disk:
1. kmod failed to exec /sbin/modprobe -s -k block-major-8 errno=2
Is this message relevant? This is a new installation of sarge and so
I've not yet run depmod -a to create the module database. So is this
error to be expected at this point? Or is it a hint of trouble? I
assume the reiserfs driver is in the kernel and does not require being
loaded by modprobe. The program /sbin/modprobe exists on sdc. I've no
idea what errno=2 is.
With the target disk (sdc1) mounted on my running system (sda), I did
try to run depmod from a chroot. Although I do have
/lib/modules/2.6.7-1-386 directory on the target disk (sdc), when I
try to create a module database from chroot:
:/# depmod -a
depmod: Can't open /lib/modules/2.4.18-bf2.4/modules.dep for writing
It seems depmod is looking at the running system (sda), which uses
kernel 2.4.18-bf2.4, rather than the target system with which has the
2.6.7-1-386 kernel. Is this behavior to be expected?
On sdc1 I do have /lib/modules/2.6.7-1-386 directory that appears to
hold the necessary modules, such as
/lib/modules/2.6.7-1-386/boot/initrd.img-2.6.7-1-386 and
/lib/modules/2.6.7-1-386/kernel/fs/reiserfs/reiserfs.ko
The root partition of the target disk is mounted locally on sda
/mnt/debinst:
ls -l /mnt
drwxr-xr-x 25 root root ... debinst
2. VFS: Cannot open root devices "sdc1" or 08:21
The device I want to mount is definitely sdc1. And the file system can
be mounted on it, for I can mount the root fs by using a boot loader
installed in the MBR of my current system (sda). However, I can't boot
by using the grub boot loader installed on diskette, even though the
grub stanzas are the same).
Why "devices" (plural)? I assume that "08:21" is the major:minor
device number, and is equivalent to "sdc1", not an alternative to
sdc1. Or am I wrong here?
3. Please append a correct "root=" boot option
Here is the grub stanza that works when the grub boot loader is on
my current (sda) MBR, but the same stanza does not work when on the
floppy:
root (hd2,0)
kernel /vmlinuz root=/dev/sdc1 ro
Given that "vmlinuz" is a symlink to the kernel in /boot, and the grub
stanza works when booting sdc from a bootloader on sda MBR, I assume
the syntax of the stanza is correct. Am I right to infer that the
problem is therefore not a failure locating the sdc1 device, but
mounting it, such as not finding a reiserfs driver?
4. kenel panic: VFS: unable to mount root fs on 08:21
Is it possible that the mount failure results from there being no
reiserfs driver present? I added reiserfs_stage1_5 to the /boot/grub
directory on the diskette, but it didn't help. I assume I don't need
it because the kernel I'm using (the stock 2.6.7-1-386) supplies it
and makes it available prior to trying to mount the root fs. Is this
assumption correct?
One anomaly. I found that I could not create a symlink from grub.conf
to menu.lst on the floppy, even though I'm sure I've done it
before. Is this the result of my having formatted the diskette DOS? I
simply added both grub configuration files instead. but assume I could
delete one of them as long as I have no intention of booting RedHat
with the floppy.
Haines Brown
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