[Unionfs] UnionFS as root filesystem

[Marcelo Ricardo Leitner]

Em Quarta 15 Março 2006 11:12, iSteve escreveu:
> On Wed, 15 Mar 2006 15:13:00 +0100
>
> Olivier Evalet <evaleto at programmers.ch> wrote:
> > It could help you,
> >
> > linuxrc must have PID==1 to start correctly sbin/init ! Have a look on
> > your boot params. Below my config for a 2.6 kernel:
> > root=/dev/ram0 init=/linuxrc rw
> >
> > I did a complet and small initrd with gentoo-uclibc that mount a unionfs
> > backend (debian/ubuntu/gentoo) as rootfs, configure the backend and
> > start /sbin/init.
> >
> >
> > Olivier
>
> To expand this a little:
> The general idea with initrd is, that you are not guarantedd that your
> linuxrc will have pid 1. You, however, need pid 1, since various init
> implementations (most commonly the sys v init) behave differently if you
> have other pid.
>
> Therefore, you should probably let (as suggested above) the initrd only set
> root filesystem to /dev/ram0 (it's somewhere in /proc, no idea where; or
> you can just set it in bootloader and pray noone changes it) and write
> yourself a short /sbin/init in the initrd, which would perform the actual
> execution of the init on the target filesystem.

Sorry the late, but maybe it's:

echo 0x0100 > /proc/sys/kernel/real-root-dev

This allows me to run pivot_root normally, just like a root over nfs or 
anything else.

Regards,
Marcelo.