# kernel panic after hard reboot [solved]

## damoncf

I rebooted my system after it wouldn't totally wake up from being asleep and am getting the following error no matter what kernel I use :

```

No File System Could Mount Root, tried: ext3 ext2 vfat msdos

Kernel Panic - not syncing: vfs : unable to mount root fs on unknown-block (8,3)

```

I currently only have one hard drive and it is partitioned into boot, (ext2) swap, and my / (ext3)

If you need anything else just ask.

DamoncfLast edited by damoncf on Mon Sep 07, 2009 7:15 pm; edited 1 time in total

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## redwood

Can you boot from a rescuecd or livecd?

If so, can you mount your disk partitions?

Then you can repair your system by chroot'ing into it:

```

swapon /dev/<swap partition>

mount /dev/<root partition> /mnt/gentoo

mount /dev/<boot partiton> /mnt/gentoo/boot

mount -t proc proc /mnt/gentoo/proc

mount -o bind /dev none /mnt/gentoo/dev

chroot /mnt/gentoo /bin/bash

env-update && source etc-profile

```

Have you upgraded your kernel or udev?

The latest udev doesn't work with older kernels, 

and so you could be missing needed /dev nodes.

What does your grub line look like?

When you say your computer was asleep, do you mean it was suspended to RAM or DISK?

or merely that the display had gone into powersaving mode?

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## kyrylo

I had the same problem.

You need to backup your /boot partition.

Emerge grub again:

```
# emerge -av grub
```

Update menu.lst file from your backup-copy of /boot partition.

After that:

```
# grub-install --no-floppy /dev/<you_hard>
```

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## damoncf

 *Quote:*   

> Have you upgraded your kernel or udev? 

 

No haven't updated in over a month and have rebooted in the past month w/o error.

 *Quote:*   

> What does your grub line look like?

 

```
#Which listing to boot as default. 0 is the first, 1 the second etc.

default 0

#How many seconds to wait before teh default listing is booted.

timeout 30

#Nice, fat splash-image to spice things up ;)

#Comment out if you dont have a graphics card installed

splashimage=(hd0,0)/grub/splash.xpm.gz

title=Gentoo New kernel 

#Partition where the kernel image (or operating system) is located

root (hd0,2)

kernel (hd0,0)/vmlinuz root=/dev/sda3

title=Gentoo old kernel

root (hd0,2)

kernel (hd0,0)/vmlinuz.old root=/dev/sda3

#old kernel that works

title=Gentoo 2.6.27

root (hd0,2)

kernel (hd0,0)/vmlinuz-2.6.27-gentoo

```

 *Quote:*   

> When you say your computer was asleep, do you mean it was suspended to RAM or DISK?
> 
> or merely that the display had gone into powersaving mode?

 

I believe it was suspended to ram.  KDE 4.3 is configured to suspend to ram after a while if not in use and unplugged for a certain length of time.

 *Quote:*   

> 
> 
> Update menu.lst file from your backup-copy of /boot partition.
> 
> After that:
> ...

 

This gives me:

```

The file /boot/grub/stage1 not read correctly.

```

----------

## redwood

You say you have one drive with 3 partitions:

```

sda1 /boot ext2    #This is where your kernel is located

sda2 swap 

sda3 /       ext3

```

Where did you install grub to? the MBR or to a partition?

If you chroot into your filesystem and run grub

```

grub> find /boot/grub/stage1

   (hd0,0)

grub> root(hd0,0)  # kernel is located on 1st partition of 1st drive

grub> setup (hd0)  #install grub to MBR of 1st drive

grub> quit

```

Then your /etc/grub/grub.conf

```

title=Gentoo

#location of kernel is on 1st partition of 1st drive:

root (hd0,0) 

# The kernel is in the folder /boot of the 1st partition of 1st drive:

kernel /boot/vmlinuz root=/dev/sda3

```

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## gerard27

This is a typical misunderstanding of grub's "root" and linux root.

Grub's root is where the kernel and grub directory are.

root (hd0,2) is where your linux root partition is.

Should be (hd0,0)!

Gerard.

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## damoncf

Thank you for the help. I think it was grub command line stuff as well as editing my grub.conf file that fixed it for anyone else that finds themselves in my shoes.

Damoncf

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