What is the logic to mount overlay at booting?

For Developers
1

Hi all,

[    9.919896] block: extroot: not configured
[    9.925195] mount_root: no usable overlay filesystem found, using tmpfs overlay
[    9.933388] mount_root: BUG: no suitable fs found

Check mount_root, it support mounting jffs2 for overlay. But it always fail to mount, why?

It is okay to mount with manual mount.

root@OmniVision OA8000-101c:~# mount -t jffs2 /dev/mtdblock2 /overlay/
cat /p[  229.062545] jffs2: notice: (1130) jffs2_build_xattr_subsystem: complete building xattr 
subsystem, 0 of xdatum (0 unchec.


root@OmniVision OA8000-101c:~# mount
none on / type rootfs (rw)
proc on /proc type proc (rw,nosuid,nodev,noexec,noatime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,noatime)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime)
/dev/mtdblock4 on /etc/factory type vfat (ro,noatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,erro)
tmpfs on /tmp/root type tmpfs (rw,noatime,mode=755)
tmpfs on /mnt type tmpfs (ro,relatime)
tmpfs on /dev type tmpfs (rw,nosuid,noexec,noatime,size=512k,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,noatime,mode=600,ptmxmode=000)
/dev/mmcblk0p1 on /mnt type vfat (rw,relatime,fmask=0000,dmask=0000,allow_utime=0022,codepage=437,iocharset=iso8859-1,shortname=)
/dev/mtdblock2 on /overlay type jffs2 (rw,relatime)

Check partition name.

root@OmniVision OA8000-101c:~# cat /proc/mtd 
dev:    size   erasesize  name
mtd0: 01000000 00001000 "FW"
mtd1: 00032000 00001000 "Env"
mtd2: 00dbb000 00001000 "rootfs_data"
mtd3: 00010000 00001000 "WIFI"
mtd4: 00200000 00001000 "factory"

Any suggestion to resolve this issue? Thanks.

2

Any modifications (settings, passwords, ...) you make are stored on the overlay. Without the overlay no modification is possible. Possible causes for a broken overlay are often lack of space.

1 Like
3

Hi @Borromini

Thanks and do you know why my rootfs_data partition always fails to mount?

At ubifs, I know I have to create rootfs_data volume name for overlay partition.
At jffs2, I don't know how to create volume for my overlay partition.
Looks like this is the reason why fail to mount overly. Any suggestion? Thanks.

4

I use jffs2 as overlay file system.
At booting, device always fail to mount overlay. The log are

[    9.796357] jffs2: notice: (144) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orph.
[    9.812820] block: attempting to load /tmp/jffs_cfg/upper/etc/config/fstab
[    9.820127] block: unable to load configuration (fstab: Entry not found)
[    9.827169] block: attempting to load /tmp/jffs_cfg/etc/config/fstab
[    9.833917] block: unable to load configuration (fstab: Entry not found)
[    9.840812] block: attempting to load /etc/config/fstab
[    9.846963] block: extroot: not configured
[   12.511919] jffs2: notice: (142) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orph.
[   13.174377] block: attempting to load /tmp/jffs_cfg/upper/etc/config/fstab
[   13.181559] block: unable to load configuration (fstab: Entry not found)
[   13.188678] block: attempting to load /tmp/jffs_cfg/etc/config/fstab
[   13.195454] block: unable to load configuration (fstab: Entry not found)
[   13.202360] block: attempting to load /etc/config/fstab
[   13.208619] block: extroot: not configured
[   13.215058] mount_root: overlay filesystem has not been fully initialized yet
[   13.223421] mount_root: switching to jffs2 overlay
[   13.231436] overlayfs: upper fs does not support tmpfile.
[   13.240871] mount_root: pivot_root failed /mnt /mnt/rom: Invalid argument
[   13.247968] mount_root: switching to jffs2 failed - fallback to ramoverlay
[   13.255582] mount_root: opening /proc/filesystems failed: No such file or directory
[   13.263532] mount_root: BUG: no suitable fs found

Anyone can help to debug which part is wrong? at kernel option or ? Please help. Thanks.