[solved] could not find root block device

Tony0945 · Posted: Tue Apr 29, 2014 1:38 pm Post subject:

I had a similar problem two weeks ago when updating my drive hardware. This may be a grub configuration problem. IIRC, what I finally did was boot sysrescuecd, follow gentoo handbook chapeters 4,6,10 to chroot, mount the boot drive (separate boot partition) then while chrooted ran "grub-install /dev/sda" . But for days both grub and grub-install refused to find the boot files.

My drive configuration is boot partition on sda1, swap on sda2, real root ('/') on sda3, no sda4. I had to edit /etc/fstab because my old drive had a fourth backup partition on sda4 and while I was swapping drives, drive sdb was a different drive. Put a crosshatch (#) in front of any drives or partitions that are at this moment attached. If you run 'grub' rather than 'grub-install', the command "find /boot/grub/stage1" should come back with (hd0,0). If it doesn't, there is a configuration error. Mine kept coming back with (hd0,2) until I did what I said above in paragraph one. The fstab troubles came later in the boot.

There may be more info here: http://www.supergrubdisk.org/wiki/Howto_Fix_Grub

I'm running legacy grub (0.97).

ch64 · Guru Joined: 09 Jun 2010 Posts: 412

Hi.
I have compiled only that ata_piix. It seems like that this is the driver.
Because i have /proc/partitions filled with partitions.
But in /dev/ there is nothing populated. I have DEVTMPFS=y

Tony0945,
i don't really think that i have a grub error.

NeddySeagoon · Posted: Wed Apr 30, 2014 8:20 pm Post subject:

ch64,

If you can see into /dev then grub has done its thing and loaded the kernel and initrd file.
Its possible that you are passing incorrect parameters to the kernel, so the initrd is not used but then you would not have a shell to see into /dev to observe that it was empty.
That means grub looks good.

Do you have MOUNTDEVTMPFS in your kernel?
The option is hidden until you select DEVTMPFS.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

ch64 · Guru Joined: 09 Jun 2010 Posts: 412

For me! it seems like that the initrd isn't loaded.
Normally it puts out a huge list of drivers loaded.
But for me there is only: "loading initrd" but no list...

NeddySeagoon · Posted: Thu May 01, 2014 8:38 pm Post subject:

ch64,

Post the output of

ch64 · Guru Joined: 09 Jun 2010 Posts: 412

http://pastebin.com/wiXQhPJH
http://pastebin.com/5G5kTV2V

On the grub.conf i only use the first entry.
The others didn't work, too.

Hey i'm now on my irc server. irc.it-flash.de #gentoo

for the history of this thread: it's empty overall. But now i'm online on it.

That title=Gentoo Linux 2.6.29 is booting. But i have to go in interactive mode and disable udev. Because of no devtmpfs=y in the 2.6.29. (starts with 2.6.32)

NeddySeagoon · Posted: Sat May 03, 2014 1:23 pm Post subject:

ch64,

Its been a long time since you needed to tell the kernel about the initrd which is what

ch64 · Guru Joined: 09 Jun 2010 Posts: 412

On my Quadcore PC i'm booting with this:

ch64 · Guru Joined: 09 Jun 2010 Posts: 412

It is not working on the laptop. And the problem is still :p not solved.
That last posting was only telling you, that you can boot with that root=/dev/ram0 option on newer kernels.

I have stopped working on the machine which is causing the thread, because i have no time and space at this time for more tests.

But with some freetime, i will look after it again.

Tony0945 · Posted: Mon Aug 18, 2014 10:27 pm Post subject:

Just was looking again at that grub.conf:

ch64 · Guru Joined: 09 Jun 2010 Posts: 412

No. That grub config, WinXP is from an old install. I have partitioned a new, bigger disk.
Now with kernel 3.18.1 it is the same error. could not find root block device in .
When i type in shell and then: mount /dev/sda1 /newroot i get:
mounting /dev/sda1 on /newroot failed no such file or directory

I can find the two partitions, root & swap in /proc/partitions

So i think i'm getting closer to a solution, here...

A short google brings back the fascination to me. There must be a possibilty to access root.

Somebody has an idea about the error: [i]no such file or directory[/b] when mounting /dev/sda1 on the /bin/ash shell?

update:
nah, the problem is, the device sda1 is not populated into /dev/ ... http://www.gentoo-wiki.info/Acer_Extensa_5220
There i found out that sata ahci is the right driver... i have it compiled in *

update2:

the lsmod is completelly empty. and when i cat the modules.cache file there is no ata driver in it.
also when i modprobe a driver which is in that file like raid10 ... it is not showing in lsmod.
it remains empty!

update3:
One thing was strange.. in the drivers directory, there were no *.ko modules for the ata driver.
So genkernel did not compile what i told it to do in the kernel .config
Now i looked over the version of genkernel.
It's: 3.4.10.906 damn old...
I now install the newest version and will look, if it compiled that drivers.

ch64 · Guru Joined: 09 Jun 2010 Posts: 412

Yehaah!
Now after about 1 year of sometimes looking at it, i have solved the error.
I had to update to the neweset genkernel version.
Also i have the real_root=UUID=UUID in the grub.conf

thanks for all your help.