mizy overlay filesystem usage

some overlay commands

• overlay info - show some info about overlay image
• overlay save -f - save change to persistent storage
• overlay.gz2jffs - convert tar.gz user data to jffs (last system can store user data as raw tar.gz format just on block device without any file system )

examples

MMC storage, user data in jffs

[email protected]:/etc/rc.local.d# overlay info
[i] dev /dev/mmcblk0
==miZy mmc header
16777216                                                       
orange_pi_zero_miZy-sys2info-id-.MMC.hybrid.16M.8192.bin       
miZy_spi_image_builder Fri Nov  2 20:44:11 2018 ## hyphop ##   
==
[i] parts: uboot=524288;script=65536;dtb=65536;kernel=3801088;initrd=7798784;user=4521984
[i] total size: 16777216
[i] user data offset: 12255232
[i] user data size: 4521984
[i] LOOP: /dev/loop0
[i] MTD: /dev/mtd7
[i] MTDBLK: /dev/mtdblock7
/dev/mtdblock7 /tmp/user.MMC jffs2 ro,noatime 0 0
/dev/mtdblock7            4416       272      4144   6% /tmp/user.MMC

MMC storage, if user data in tar.gz

overlay info

[i] dev /dev/mmcblk0
==miZy mmc header
16777216                                                       
orange_pi_zero_miZy-sys2info-id-.MMC.hybrid.16M.8192.bin       
miZy_spi_image_builder Fri Nov  2 20:44:11 2018 ## hyphop ##   
==
[i] parts: uboot=524288;script=65536;dtb=65536;kernel=3801088;initrd=7798784;user=4521984
[i] total size: 16777216
[i] user data offset: 12255232
[i] user data size: 4521984
[i] LOOP: 
[i] MTD: 
[i] MTDBLK: 

convert gz to jffs

overlay.gz2jffs yes

[i] check /dev/loop0 gz: yes
[i] usage /opt/overlay.gz2jffs yes
[email protected]:/etc/rc.local.d# overlay.gz2jffs yes
[i] check /dev/loop0 gz: yes
ff* => dd of=/dev/mmcblk0 count=552 bs=8192 seek=1497
551+1 records in
551+1 records out
4519936 bytes (4.3MB) copied, 2.009147 seconds, 2.1MB/s
[i] check /dev/loop0 gz: 
[i] force mode
rsync -av --delete --inplace /overlay /tmp/user
[i] /dev/mtdblock7 /tmp/user.MMC jffs2 ro,noatime 0 0
[w] /tmp/user mounted as read only
[i] force mode / remount ro to rw /tmp/user.MMC
sending incremental file list
overlay/
overlay/etc/
overlay/etc/hostname
overlay/etc/rc.local

sent 14,870 bytes  received 207 bytes  30,154.00 bytes/sec
total size is 14,102  speedup is 0.94
[i] force mode / remount rw to ro /tmp/user.MMC

mizy filesystem structure

mount

• rootfs on / type rootfs (rw)
• /dev/root on / type squashfs (ro,relatime)
• devtmpfs on /dev type devtmpfs (rw,relatime,size=185408k,nr_inodes=46352,mode=755)
• none on /proc type proc (rw,relatime)
• tmp on /mnt type tmpfs (rw,relatime)
• /dev/ram0 on /rom type squashfs (ro,relatime)
• tmp-overlay on /overlay type tmpfs (rw,relatime)
• overlayfs on / type overlayfs (rw,sync,noatime,lowerdir=/mnt/ro,upperdir=/mnt/rw)
• sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,noatime)
• cgroup on /sys/fs/cgroup type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event,blkio,freezer,devices,memory,cpuacct,cpu,cpuset)
• tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime)
• tmpfs on /dev type tmpfs (rw,nosuid,relatime,size=512k,mode=755)
• devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,mode=600,ptmxmode=000)
• debugfs on /sys/kernel/debug type debugfs (rw,noatime)

overlay layers

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          < ROOT FS OVERLAY >
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RAM-RO SQUSHFS | RAM-RW (online changes)
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STORAGES | SPI | SD | MMC | USB | ...
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