[PLUG] FW: Can't bootup linux

Carlos Konstanski ckonstan at lunarlogic.com
Sun Aug 14 00:05:08 UTC 2005


Use fdisk -l to see where your partitions are.  Do you have /boot
mounted on its own partition?  You'll have to mount it:

cd /boot
ls -l

If you see 0 entries listed, try this:

cd /
mount /dev/hda1 /boot   # This assumes /dev/hda1 is your /boot partition
cd /boot
ls -l

You should see files now.

On redhat, /boot/grub/grub.conf should be the location of the file.

>From a grub prompt at bootup time, you can manually type in any commands
that one would find in a grub.conf file.  You can try out various
vmlinuz lines from there, without having to get all the way to a place
where you can edit the grub.conf file.  You can get to the prompt by
typing "c" when yu see the grub menu screen.  Try this out for fun at
the grub prompt:

root (hd0,0) # Use the right numbers, of course.  These point to the first
              # partition on the first drive, a good place to put your
              # /boot partition.  It is the equivalent of /dev/hda1.

configfile /grub/grub.conf # This assumes /boot is its own partition.
                            # If /boot is part of your root filesystem,
                            # use the path /boot/grub/grub.conf instead.

These 2 commands at the grub prompt will manually launch the grub menu.
You can also type in commands like the following to boot "manually":

root (hd0,0)
kernel /vmlinuz-2.6.12-gentoo-r4 root=/dev/hda5 ro lang=en vga=791
boot

This is straight out of my menu.lst file (the debian and gentoo name for
grub.conf).  The grub.conf file's entries get executed as-is when you
choose one at bootup time, as if you typed them yourself at the prompt.
As you can see, my root filesystem is on /dev/hda5, the first extended
partition of the disk.  You alluded to a syntax that lets grub figure
out the root filesystem partition for itself (root=LABEL=/).  I suggest
spelling it out explicitly as I have done here.

Do you need an initrd image?  If it's a stock redhat kernel, I would say
it's a certainty.  I have not used an initrd image for a long time, so I
have no known working example to offer you.  But it's not too hard; it
looks like the "kernel" line, except with no params.  Here's a googled
one:

initrd /initrd-2.4.18-0.12.img

You would put this somewhere between the "root" line and the "boot" line.
Again, you can see that "/boot" is not part of the path.  This is
because /boot is its own partition on this machine.  If /boot were part
of the root filesystem, all the paths in grub.conf would have "/boot"
prepended.

With a stock redhat kernel, your kernel will be unable to read your hard
drive without the assistance of the modules in that initrd image.  I'd
bet that is your problem.  No ATA support, no workie.  Add an initrd
line to your grub commands in grub.conf, or type the lines in manually
from the grub prompt.

Carlos

On Sat, 13 Aug 2005, James H. Webb wrote:

> Date: Sat, 13 Aug 2005 19:37:33 -0400
> From: James H. Webb <jimwebb at charter.net>
> Reply-To: "General Linux/UNIX discussion and help; civil and on-topic"
>     <plug at lists.pdxlinux.org>
> To: PLUG <plug at lists.pdxlinux.org>
> Subject: [PLUG] FW: Can't bootup linux
> 
> I've gone into the RH 8 linux rescue mode and am at the /bin/sh-2.05b#
> prompt.  I'm in a new territory here.  All of this is a new territory for
> me.
>
> Doesn't anyone have any ideas where to go.  I've been trying to find my
> grub.conf file or boot folder, but no avail.
>
> TIA,
>
> Jim
>
>> -----Original Message-----
>> From: James H. Webb [mailto:jimwebb at charter.net]
>> Sent: Saturday, August 13, 2005 6:15 PM
>> To: PLUG
>> Subject: FW: Can't bootup linux
>>
>>
>>
>>
>>> -----Original Message-----
>>> From: James H. Webb [mailto:jimwebb at charter.net]
>>> Sent: Wednesday, August 10, 2005 1:51 PM
>>> To: PLUG
>>> Subject: FW: Can't bootup linux
>>>
>>>
>>> I googled and got the following information; and Where is the
>>> correct root partition in RH8?
>>>
>>> ok its possible that ur boot directory has changed
>>> boot linux in rescue mode
>>> i.e bot it from CD & type
>>>
>>> linux rescue
>>> at boot prompt after that check in /etc/grub.conf file & check
>>> wheather it points to correct root partition
>>>
>>> if u dont know abt where ur root partition is :
>>> then give this command at the cmd-prompt
>>>
>>> #fdisk -l
>>>
>>> I also saw this: root=LABEL=/
>>> to
>>> root=/dev/hda*
>> I tried this and went into the flash screen and edited the
>> parameters to ro root=/dev/hda1.
>> I received the following message the Kernel panic: No init found.
>>  Try passing init= option to kernel.
>> I then tried editing in this line: kernel /vmlinuz-2.4.18-18.8.0
>> ro root=/dev/hda1 init = 3
>> I get the same message of Kernel panic: No init found.  Try
>> passing init= option to kernel.
>>
>> What gives here????
>>
>> TIA,
>>
>> Jim
>>
>>>
>>>> -----Original Message-----
>>>> From: James H. Webb [mailto:jimwebb at charter.net]
>>>> Sent: Tuesday, August 09, 2005 10:59 PM
>>>> To: PLUG
>>>> Subject: Can't bootup linux
>>>>
>>>>
>>>> I switched the HD to another box and get the following message
>>>> VFS:  Cannot open root device "Label=?" or )):))
>>>> Please append a correct "root=" boot option
>>>> Kernel panic: VFS: Unable to mount root fs on 00:00
>>>>
>>>> It looks like it's having problems seeing root on the HD.
>>>>
>>>> any suggestions.
>>>>
>>>> Jim
>
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