2.4 kernel style boot using pivot_root (RFC)

[Jan Rekorajski]

[piątek, 08 marzec 2002], Michal Moskal napisał(a):

> Hi,
> 
> Yesterday qboosh suggested me some additions to bsp to allow pivot_root
> style boot using it. I thought it would be funny to have system booted up
> this way, so I did it :)
> 
> There were some more or less severe problems during it.
> 
>   1) old root (initrd) has to be placed somewhere on real root, I suggest
>      /var/lib/bsp/oldroot [RFC]

Why not /boot/root ?

>   2) we cannot unmount old root while bsp is running, I first thought we
>      can unmount and freeramdisk old root in rc-scripts, however there is
>      no standalone freeramdisk utility and even beside it, unmounting in
>      rc-scripts seems messy, so I decided to use two stage bsp bootup.

Works for me and my Rescue CD.
freeramdisk = /sbin/blockdev --flushbufs /dev/rd/*

>      Bsp from initrd, at end of its life does exec /sbin/bsp (from real
>      root filesystem, in the meantime we have to close /dev/console but
>      this ain't problem), that unmounts oldroot, frees ramdisk and does
>      exec /sbin/init. This works :) anyway RFC.

I can send you linuxrc.c from Rescue CD.

>   3) there is problem with devfs. We can mount it in stage 1, unmount
>      before trying to unmount oldroot, and mount it again in real root,
>      so we don't have to have /dev/ram0 and /dev/console on root filesystem,
>      but what then? leave it mounted? what about people not using it?
>      and what if there is not devfs in kernel? RFC

Just use normal /dev at first stage.

Janek
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