# [SOLVED] Kernel lies about not finding a valid root device

## mauricev

I'm trying to boot from a USB flash drive and it works so long as I manually enter the device designation. 

That is, on its own, the kernel complains 

```

Activating mdev

Determining root device...

!! Could not find the root block device LABEL=root.

```

Now where it says 

```

Please specify another value or: press Enter of the same, type "shell" for a shell, or "q" to skip...

root block device(LABEL=root) ::

```

I just type LABEL=root and it works!

So it's as if the kernel had been lying and it did find it.

Here's the kernel line:

```

title=Gentoo Linux 2.6.29-rc8-tip

root (hd0,0)

kernel /xen.gz

module /kernel-genkernel-x86_64-2.6.29-rc8-tip root=/dev/ram0 init=/linuxrc ramdisk=8192 real_root=LABEL=root doscsi rootdelay=30

module /initramfs-genkernel-x86_64-2.6.29-rc8-tip

```

I had been trying this with real device designations (i.e., /dev/sdb2) and switched to the labels to see if that would help, which obviously it didn't. I also thought it could be an issue with the USB device not being ready, but rootdelay=30 didn't make a difference.

The kernel is a dom0-privileged kernel running under Xen.Last edited by mauricev on Mon Mar 23, 2009 7:00 pm; edited 1 time in total

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## mamac

Ha...isn't it this "delay" argument you should pass to load the kernel? I had such an issue but unfortunately I can't remember the argument sorry.

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## mamac

Ha ! Isn't it rootdelay argument?

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## Kobboi

 *mauricev wrote:*   

> 
> 
> That is, on its own, the kernel complains 
> 
> ```
> ...

 

Also note that it's not the kernel talking, but the init script in the initrd.

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## mauricev

 *Quote:*   

> Also note that it's not the kernel talking, but the init script in the initrd.

 

This was helpful.   :Idea:  The actual init script is /usr/share/genkernel/defaults/linuxrc. Once I looked inside it, I see the problem.

 *Quote:*   

>  Isn't it rootdelay argument?

 

Not anymore! Apparently, at some point, someone changed it to scandelay.

Now, with scandelay it's booting fine.

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