How do I rebuild the initrd?

[Tom Diehl]

Hi,

I need to know if anyone has the magic incantation to get mkinitrd to build a
proper initrd from either rescue mode or the live cd. I need to put a drive
into another box that has a different disk controller in it.

If I boot into rescue mode and setup a chroot, when I run mkinitrd I get
an error that says "error opening /sys/block: No such file or directory.

I also get the same error if I try to do the same thing from the live cd.

The resulting initrd is unusable because the kernel cannot find the root
partition.

I there a howto somewhere for this?

I tried google but either I am not looking for the right thing or it does not
exist.

Regards,

Tom