On 21 July 2003 23:53, Rene Mayrhofer wrote:
> Hi all,
>
> [Please CC me in replies, I am currently not subsribed to this list.]
>
> I am currently using 2.4.21-ac4 (with a few other patches, but none of
> them seems to touch pivot_root in any way) on a VIA EPIA M6000 board,
> with works pretty fine and seems more stable than the previsouly used
> 2.4.21-rc2. However, there is one problem that I am unable to solve:
>
> When switching the root filesystem on the fly basically with:
>
> <prepare the new root fs, which is in fact a cramfs>
> mount -t cramfs /dev/rd/0 $mntpoint
> cd $mntpoint
> mount -nt proc none proc/
> mount -nt devfs none dev/
> /sbin/pivot_root . mnt <dev/console >dev/console 2>&1
> <snip, some further preparations on the new root fs>
> /usr/sbin/chroot . /sbin/telinit u <dev/console >/dev/console 2>&1
btw you probably have to remove leading / ^^^
> <snip>
> exit 0
Hm... I thought you are running with pid 1 and have to do
exec chroot . /sbin/init <dev/console >/dev/console 2>&1
or the like as a final command.
> it no longer works as expected. I should probably note that the
> redirections to /dev/console were not necessary for 2.4.21-rc2, I tried
> them with 2.4.21-ac4. While the above commands did the trick for
> 2.4.21-rc2, with 2.4.21-ac4 the kernel processes leave the console on
> the old root fs open:
>
> lsof -n | grep mnt
> keventd 2 root 0u CHR 5,1 16 /mnt/dev/console
> keventd 2 root 1u CHR 5,1 16 /mnt/dev/console
> keventd 2 root 2u CHR 5,1 16 /mnt/dev/console
> ksoftirqd 3 root 0u CHR 5,1 16 /mnt/dev/console
> ksoftirqd 3 root 1u CHR 5,1 16 /mnt/dev/console
> ksoftirqd 3 root 2u CHR 5,1 16 /mnt/dev/console
> kswapd 4 root 0u CHR 5,1 16 /mnt/dev/console
> kswapd 4 root 1u CHR 5,1 16 /mnt/dev/console
> kswapd 4 root 2u CHR 5,1 16 /mnt/dev/console
> bdflush 5 root 0u CHR 5,1 16 /mnt/dev/console
> bdflush 5 root 1u CHR 5,1 16 /mnt/dev/console
> bdflush 5 root 2u CHR 5,1 16 /mnt/dev/console
> kupdated 6 root 0u CHR 5,1 16 /mnt/dev/console
> kupdated 6 root 1u CHR 5,1 16 /mnt/dev/console
> kupdated 6 root 2u CHR 5,1 16 /mnt/dev/console
> kjournald 7 root 0u CHR 5,1 16 /mnt/dev/console
> kjournald 7 root 1u CHR 5,1 16 /mnt/dev/console
> kjournald 7 root 2u CHR 5,1 16 /mnt/dev/console
> scsi_eh_0 81 root 0u CHR 5,1 16 /mnt/dev/console
> scsi_eh_0 81 root 1u CHR 5,1 16 /mnt/dev/console
> scsi_eh_0 81 root 2u CHR 5,1 16 /mnt/dev/console
>
> Does anybody have an idea what might be wrong here ?
I don't know for sure but it seems like kernel daemons share fds with pid 1.
On my system:
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
init 1 root cwd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
init 1 root rtd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
init 1 root txt REG 0,8 19688 77715 /app/util-linux-2.11p/sbin/init (172.16.42.75:/.rootfs/.std)
init 1 root mem REG 0,8 832636 8248 /app/glibc-2.3/lib/ld-2.3.so (172.16.42.75:/.rootfs/.std)
init 1 root mem REG 0,8 69355 8254 /app/glibc-2.3/lib/libcrypt-2.3.so (172.16.42.75:/.rootfs/.std)
init 1 root mem REG 0,8 16153080 8249 /app/glibc-2.3/lib/libc-2.3.so (172.16.42.75:/.rootfs/.std)
init 1 root 3u FIFO 0,6 405 /dev/initctl
keventd 2 root cwd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
keventd 2 root rtd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
keventd 2 root 3u FIFO 0,6 405 /dev/initctl
ksoftirqd 3 root cwd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
ksoftirqd 3 root rtd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
ksoftirqd 3 root 3u FIFO 0,6 405 /dev/initctl
kswapd 4 root cwd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
kswapd 4 root rtd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
kswapd 4 root 3u FIFO 0,6 405 /dev/initctl
bdflush 5 root cwd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
bdflush 5 root rtd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
bdflush 5 root 3u FIFO 0,6 405 /dev/initctl
kupdated 6 root cwd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
kupdated 6 root rtd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
kupdated 6 root 3u FIFO 0,6 405 /dev/initctl
rpciod 16 root cwd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
rpciod 16 root rtd DIR 0,8 1024 65282 / (172.16.42.75:/.rootfs/.std)
rpciod 16 root 3u FIFO 0,6 405 /dev/initctl
See? fd 3 is open to /dev/initctl in init AND in kernel daemons.
I conclude that daemons simply share fd table with init.
So you might try to do the exec chroot . /sbin/init trick
and see whether that works.
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This archive was generated by hypermail 2b29 : Wed Jul 23 2003 - 22:00:45 EST