Comment 49 for bug 642421

I investigated a bit further and my idea above is clearly wrong. If I put a printf right at the beginning of the initramfs init script that triggers after the "FATAL" message, so this is clearly a modprobe triggered by kernel code before init starts running. My next suspicion is that the kernel calls modprobe before it has finished unpacking the initramfs, so that /sbin/modprobe is already available but modules.dep is not. And when I repacked the initramfs with modules.dep as the very first file (well, after ".", "./lib", "./lib/modules" etc) the error went away.

There are a few places in the kernel where modprobe can be called from. Sticking printk statements in there should show which it is and what command line is being called. That will have to wait until I get round to it though.