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Busybox troubleshooting

Uninformative mount error

Maybe, mount of busybox can deliver strange error messages, more strange then default mount in GNU/Linux distributions. This is because they struggle to let their mount small and do not try to implement fancy things like clear error messages (which may require lot of code to probe the system for status).

So, what to do when there is an informative error like that? My experience shows some clues:

mount: mounting /dev/sda1 on /mnt failed: No such file or directory

Specify the system you want to build with the -t flag:

# mount -t ext3 /dev/sda1 /mnt

mount: mounting /dev/sda1 on /mnt failed: No such device

If, after you specified -t, you get a problem like that, it is very likely that the kernel cannot mount the requested filesystem for you. Does the kernel supports the filesystem? Is there a module for that filesystem? Is it loaded? Check with the lsmod command:

# lsmod

You may try to load it with the modprobe command:

# modprobe ext3

If the module doesn't exist, you are in a problem. In my case, I was using a version of Debian GNU/Linux that didn't have the module, so I stole the module from a Ubuntu initrd CD and put it together with other modules on my modified initrd.

mount: mounting /dev/sda1 on /mnt failed: Invalid argument

The kernel can probably mount the filesystem, but it wrongly guess its type. Try using the -t flag as told in mount: mounting /dev/sda1 on /mnt failed: No such file or directory.