[BusyBox] pivot_root - devfs problem

[Roberto De Leo]

>
>
>>I am trying to build a floppy boot disk for my project (movix.sf.net) 
>>and I'm almost there, except for a detail: after pivoting I cannot 
>>umount the old root since I cannot umount its dev directory mounted with 
>>"-t devfs".
>>
>>I searched with google and found many messages about this topic here and 
>>there [it is thanks to them that now almost everything works] but none 
>>of them managed to solve this last problem.
>>    
>>
>
>What works for me is to configure the kernel to auto-mount the devfs on 
>/dev at boot, then after pivoting you can mount another copy of devfs on 
>the new /dev and unmount the original (e.g. now /old_root/dev) at your 
>leisure.
>
This is exactly what I am doing, but when I try to umount /old_root/dev 
I get the error message "device is busy" :-(
Almost everything works fine [i.e. doing an "exec linuxrc" the new 
system starts and so on] but I keep getting that message every time I 
try to umount /old_root/dev
Now I'll give a try to the Laurence boot image to see whether how his 
own image works.
Thanks,
 Roberto