How to use pivot_root to change new root and umount old root?

wangvictor — Tue, 26 Jun 2018 08:12:28 GMT

Hi community,

Recently I had tried to change root with pivot_root.

But I cannot umount the old root.

After some googling I summarize following steps.

mount /dev/mmcblk3p2 /newroot
cd /newroot
unshare -m
pivot_root . mnt
exec chroot . sh -c "umount /old_root; exec /sbin/init" <dev/console >dev/console 2>&1

But I was stuck in the fifth steps, it will show there is no console under /dev.

When I "ll /dev" I get all this things like below.

total 16
drwxr-xr-x 4 root root 4096 Jan 1 1970 ./
drwxr-xr-x 22 root root 4096 Jun 26 08:05 ../
lrwxrwxrwx 1 root root 11 Jan 1 1970 core -> /proc/kcore
lrwxrwxrwx 1 root root 13 Jan 1 1970 fd -> /proc/self/fd/
lrwxrwxrwx 1 root root 8 Jan 1 1970 ptmx -> pts/ptmx
drwxr-xr-x 2 root root 4096 Apr 21 2017 pts/
lrwxrwxrwx 1 root root 4 Jan 1 1970 ram -> ram1
drwxr-xr-x 2 root root 4096 Apr 21 2017 shm/
lrwxrwxrwx 1 root root 4 Jan 1 1970 stderr -> fd/2
lrwxrwxrwx 1 root root 4 Jan 1 1970 stdin -> fd/0
lrwxrwxrwx 1 root root 4 Jan 1 1970 stdout -> fd/1

How to solve this question?

Or my steps are wrong or has any problem?

Thanks in Advanced!

Re: How to use pivot_root to change new root and umount old root?

Bio_TICFSL — Wed, 27 Jun 2018 13:46:10 GMT

Hi Victor,

You have to change it in host, then backup you memory.

Regards

i.MX Processors中的主题 Re: How to use pivot_root to change new root and umount old root?

How to use pivot_root to change new root and umount old root?

Re: How to use pivot_root to change new root and umount old root?