Re: PID of init != 1 when initrd with pivot_root

[Ivan Vadovic]

> > But the problem still remains. How do I make my /sbin/init run with PID 1 
> > using initial ramdisk under the new root change mechanism? I don't want to 
> > use the old change_root mechanism...
> 
> I had the same problem when doing some development for mkCDrec.
> This project uses busybox, whose init does not run if its PID != 1.
> I asked the busybox folks same question you did and never got a response.
> 
> As a kludge, and after looking at the busybox source code, I renamed init
> to linuxrc.  In this case the program is functionally equivalent to init,
> except that it does not do the PID == 1 check.
> 
> An excerpt from my real linuxrc:
> 
> echo Pivot_root: my PID is $$
> # exec /usr/sbin/chroot . /sbin/init < dev/console > dev/console 2>&1
> # Okay, try this:
> exec /usr/sbin/chroot . /sbin/linuxrc < /dev/console > /dev/console 2>&1
> 
> /sbin/linuxrc is actually init, renamed.
> 

I fugured it out. The Documentation/initrd.txt says to use root=/dev/rd/0 with
devfs. Well, that's wrong. You should use root=/dev/ram0 even with devfs no
matter what the documentation says. And my linuxrc finaly runs with PID == 1.

Ivan Vadovic