Kernel panic: VFS: unable to mount root fs

Kevin Alm kevinalm at shenessex.heartland.net
Mon Dec 20 13:50:28 PST 2004


Markus Mahlberg wrote:

>Clark, David A., SGT - 75th Rangers wrote:
>
>  
>
>>FIRST, THE N00B INTRODUCTION STUFF:
>>
>>Hi. My name is David. My friends at work call me Sparky, and it worked as
>>a user name. A while back, I first made the switch from Windows to Linux,
>>and found Gentoo to be a good starting point for me. I was never happier.
>>:)
>>
>>Lo and behold, my wife--who is, incidentally, not very savvy with these
>>sort of things--hated it. Naturally, I installed Windows again to sleep
>>better at night, but I left half of my disc blank for the day I'd install
>>Linux again.
>>
>>Fast forward a few months, and I found LFS, which a couple people talked
>>about on the board as "the way to go if you really want to learn Linux". I
>>downloaded the most recent book, packages, and patches; burnt one of the
>>Live CDs; and off I went. I followed along with the book without a
>>hitch--learning a LOT along the way--all the way until after the part
>>where you reboot, register, and enjoy.
>>
>>NEXT, MY N00B PROBLEM:
>>
>>Kernel panic: VFS: unable to mount root fs
>>
>>I'm not a total idiot, and I THOUGHT I knew how to fix the problem, until
>>everything I knew to check checked out.
>>
>>So, I checked the FAQ, and here's where I'm at...
>>
>>Q: Did you specify the correct partition in /etc/lilo.conf?
>>A: Menu.lst applies to me because I'm using Grub. Windows is installed on
>>/dev/hda0,
>>    
>>
>          ^     
>Uhm, one might call me stupid, but there is no hda0. Should be on hda1.
>
>  
>
>>Linux on /dev/hda4 (ext3),
>>    
>>
>Just a thought:
>hda4 is supposed to be the extended partition. By using hda4 as an primary,
>you will be unable to add any partitions (e.g. home which is useful for
>backups). It may be an restriction of the MS-compatibility mode to have
>only 4 primary partitions (though I am not sure about this at the moment),
>but as you use MS your pinned to this. Better idea would be to repartition
>your disk in a way that hda4 becomes the extended partition, hda5 becomes
>the root-partition (don't forget to do an backup first). With this setup you
>will even be able to add logical dos-drives to the extended partition
>(don't use MS-fdisk for it!)
>
>  
>
>>with /boot on /dev/hda2 (ext2) and  
>>my swapfile on /dev/hda2. My guess is that menu.lst should look like this:
>>
>>root (hd0,1)
>>...
>>kernel /lfskernel-2.6.8.1 root=/dev/hda2
>>
>>That didn't work, so I tried this:
>>
>>root (hd0,3)
>>...
>>Kernel /lfskernel-2.6.8.1 root=/dev/hda4
>>
>>This is even worse because Grub gives me "File not found" and won't even
>>begin to boot. Sadly, after that, I tried in vein every combination that
>>shouldn't work in hopes that something would work.
>>
>>Q: Did you remember to rerun lilo after changing /etc/lilo.conf?
>>A: I'm using Grub, but I did rerun it anyway, and even tried installing it
>>on (hd0,1) instead of the MBR. No dice here, either.
>>
>>Q: Is support for the hard drive enabled in the kernel?
>>A: Yep.
>>
>>Q: Is support for the hard drive compiled into the kernel, not just as a
>>module?
>>A: Yep, I configured my kernel for NO modules.
>>
>>Q: Is support for the filesystem compiled into the kernel?
>>A: Yes, same as above.
>>
>>I've looked through the FAQ of course, and I didn't find anything in the
>>hints. Maybe I missed it though. I'd definitely appreciate any help... I'd
>>hate to have to fdisk the whole thing and start over.
>>

First, let's get rid of a common misconception. In menu.lst (aka grub.conf)

root(hdm,n)   where m and n are numbers,

does _nothing_. Nada. Null. Void.

That statement only has an effect in a grub prompt, where it sets up 
where a stage1 grub sector will look for menu.lst and the other stage 
files.

Unless you are using a swap file instead of a swap partition, hda2 can't 
hold both /boot and swap. Are you sure you have a seperate /boot?


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