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ro_raspi3_fs/README.md
Milan Toman f7d6dba0e1 Reorder documents to fit the use
2021-04-08 09:39:32 +02:00

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# Docker RO image
# Pre-boot
## Create base image, simpel
wget https://downloads.raspberrypi.org/raspios_lite_armhf/images/raspios_lite_armhf-2021-01-12/2021-01-11-raspios-buster-armhf-lite.zip
[temelin ro_raspi3_fs]# unzip 2021-01-11-raspios-buster-armhf-lite.zip
Archive: 2021-01-11-raspios-buster-armhf-lite.zip
inflating: 2021-01-11-raspios-buster-armhf-lite.img
[temelin ro_raspi3_fs]# ls -l
total 2267512
-rw-r--r-- 1 root root 1862270976 11. led 14.08 2021-01-11-raspios-buster-armhf-lite.img
-rw-r--r-- 1 root root 459635953 11. led 14.11 2021-01-11-raspios-buster-armhf-lite.zip
## Mount image partition locally
[temelin ro_raspi3_fs]# fdisk -l 2021-01-11-raspios-buster-armhf-lite.img
Disk 2021-01-11-raspios-buster-armhf-lite.img: 1,73 GiB, 1862270976 bytes, 3637248 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xe8af6eb2
Device Boot Start End Sectors Size Id Type
2021-01-11-raspios-buster-armhf-lite.img1 8192 532479 524288 256M c W95 FAT32 (LBA)
2021-01-11-raspios-buster-armhf-lite.img2 532480 3637247 3104768 1,5G 83 Linux
Disk offset to be mounted at loopback: part start (**8192**) * sector size (**512**) = **4194304**
[temelin ro_raspi3_fs]# losetup -o 4194304 /dev/loop0 2021-01-11-raspios-buster-armhf-lite.img
[temelin ro_raspi3_fs]# losetup -o 272629760 /dev/loop1 2021-01-11-raspios-buster-armhf-lite.img
[temelin ro_raspi3_fs]# mkdir root boot
[temelin ro_raspi3_fs]# mount /dev/loop0 boot
[temelin ro_raspi3_fs]# mount /dev/loop1 root
Enable ssh server and permit login via ssh by default
[temelin ro_raspi3_fs]# touch ./boot/ssh
Disable serial console, change root device to generic mmcblk0p2, init a resize when inserted
[temelin ro_raspi3_fs]# echo "console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet init=/usr/lib/raspi-config/init_resize.sh" > ./boot/cmdline.txt
[temelin ro_raspi3_fs]# echo "dtoverlay=disable-bt" >> ./boot/config.txt
[temelin ro_raspi3_fs]# echo "enable_uart=1" >> ./boot/config.txt
[temelin ro_raspi3_fs]# rm ./root/etc/systemd/system/multi-user.target.wants/hciuart.service
[temelin ro_raspi3_fs]# mv ./root/etc/fstab ./root/etc/fstab.bkp
[temelin ro_raspi3_fs]# cat ./root/etc/fstab | sed 's/PARTUUID=[0-9a-z\-]\+\([0-9]\)\ /dev\/mmcblk0p\1/g' > ./root/etc/fstab
Sync / umount
[temelin ro_raspi3_fs]# umount boot root
# Additional steps and remarks
1. UART > HW (already done at copy phase)
2. GSM - generic - ip config / reboot / setup (netctl, ipspace, network-manager)
- recommend netctl / ipspace, net manager has dependencies on Gnome.
3. wahtchdog mod (configuration not known, just installed)
4. BalenaOS, Hypriot, RTOS, alternatives
- BalenaOS:
Not looking all that bad, customisation not necessary. Need to test
kernel availability and modules for HW devices (CAN / Modbus)
Has option for a RO file system. Would recommend a Raspberry PI4
- Hypriot:
Dedicated docker image. Does not seem to be actively developed anymore.
Non ROFS support out of the box
- RTOS non-linux standards
RTOS would require a complete rewrite. No Java.
- Arch Linux / ubuntu ...
Arch: highly customisable, but might be challenging to maintain. Good
community support, great tutorials and documentation. Rolling release,
no full system upgrades. 64-bit available
Ubuntu: based on debian, bloated more than others, has dedicated streams
to implementthird party / paid / non-opensource code on the fly
FreeBSD:
Similar to arch, pain to get non-FBSD/GPL code signed, verified and
implemented. Very lightweight, stable. 64-bit available
# Prepare SD card
## dd to SDcard
[temelin ro_raspi3_fs]# dd if=./2021-01-11-raspios-buster-armhf-lite.img of=/dev/sdb status=progress
1854296576 bytes (1,9 GB, 1,7 GiB) copied, 377 s, 4,9 MB/s
3637248+0 records in
3637248+0 records out
1862270976 bytes (1,9 GB, 1,7 GiB) copied, 380,898 s, 4,9 MB/s
# Post-boot
[raspi /]# sudo apt-get update
[raspi /]# sudo apt-get upgrade
[raspi /]# sudo reboot
## Set up country? Wifi needed?
[raspi /]# sudo apt install network-manager #(to get nmcli, 23MB)
[raspi /]# sudo apt remove python3.7 --purge #python3.5 compatible, subject to testing
[raspi /]# sudo apt install watchdog python3.5 openjdk-8-jre #(800 MB additional)
## Disable swap
[raspi /]# sudo sync
[raspi /]# sudo swapoff -a
[raspi /]# sudo apt-get purge -y dphys-swapfile
[raspi /]# sudo rm /var/swap
[raspi /]# sudo sync
HCI / UART:
root@raspberrypi:~# ls -l /dev/serial0
lrwxrwxrwx 1 root root 7 Mar 18 16:05 /dev/serial0 -> ttyAMA0
root@raspberrypi:~# ls -l /dev/serial1
lrwxrwxrwx 1 root root 5 Mar 18 16:05 /dev/serial1 -> ttyS0
# re-create SDcard image
## make image, shrink it (
[temelin ro_raspi3_fs]# e2fsck -f -y -v -C 0 /dev/sdb2
[temelin ro_raspi3_fs]# resize2fs -p /dev/sdb2 2764800K
[temelin ro_raspi3_fs]# parted -s /dev/sdb 'print'
Model: Multi Flash Reader (scsi)
Disk /dev/sdb: 32,0GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:
Number Start End Size Type File system Flags
1 4194kB 273MB 268MB primary fat32 lba
2 273MB 3200MB 2927MB primary ext4
[temelin ro_raspi3_fs]# parted -s /dev/sdb 'resizepart 2 3105M'
## Create an empty RAW device + partitions
[temelin ro_raspi3_fs]# dd if=/dev/zero of=./ro_img.dd status=progress bs=1M count=2900
[temelin ro_raspi3_fs]# parted -s ./ro_img.dd 'mktable msdos'
[temelin ro_raspi3_fs]# parted -s ./ro_img.dd 'mkpart primary fat32 2048s 257MiB'
[temelin ro_raspi3_fs]# parted -s ./ro_img.dd 'mkpart primary ext4 257MiB 100%'
[temelin ro_raspi3_fs]# parted -s ./ro_img.dd 'print'
Model: (file)
Disk /mnt/ssd2/ro_img.dd: 3041MB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:
Number Start End Size Type File system Flags
1 1049kB 269MB 268MB primary lba
2 269MB 3041MB 2771MB primary
## Create filesystems. Need to mount with offset, again
2048 * 512 = 1048576, 526336 * 512 = 269484032
[temelin ro_raspi3_fs]# fdisk -l ./ro_img.dd
Disk ./ro_img.dd: 2,83 GiB, 3040870400 bytes, 5939200 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xded84696
Device Boot Start End Sectors Size Id Type
./ro_img.dd1 2048 526335 524288 256M c W95 FAT32 (LBA)
./ro_img.dd2 526336 5939199 5412864 2,6G 83 Linux
[temelin ro_raspi3_fs]# losetup -o 1048576 /dev/loop0 ./ro_img.dd
[temelin ro_raspi3_fs]# losetup -o 269484032 /dev/loop1 ./ro_img.dd
[temelin ro_raspi3_fs]# mkfs.vfat -F 32 -n BOOT /dev/loop0
[temelin ro_raspi3_fs]# mkfs.ext4 -L rootfs /dev/loop1
[temelin ro_raspi3_fs]# mount /dev/loop0 ./boot
[temelin ro_raspi3_fs]# mount /dev/loop1 ./root
[temelin ro_raspi3_fs]# ls -ld boot_sd || mkdir boot_sd
[temelin ro_raspi3_fs]# ls -ld root_sd || mkdir root_sd
[temelin ro_raspi3_fs]# mount /dev/sdb1 ./boot_sd
[temelin ro_raspi3_fs]# mount /dev/sdb2 ./root_sd
[temelin ro_raspi3_fs]# rsync -auP ./boot_sd/ ./boot/
[temelin ro_raspi3_fs]# rsync -auP ./root_sd/ ./root/
## Don't forget to re-do the resize at initial boot
[temelin ro_raspi3_fs]# echo "console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet init=/usr/lib/raspi-config/init_resize.sh" > ./boot/cmdline.txt
# RO part - manual
## making a RO overlay root fs => enable it in raspi-config
This only adds entries to /boot/cmdline.txt and a different overlay kernel to config.txt
By removing it, we can get to RW system manually.
-- This breaks the partition resize process. Manual resize and re-enable RO must be triggered at later stage.
Must not do this at image generation / adjust the extension process
[raspi /]# sudo raspi-config nonint do_overlayfs 0
## Mounting root as RW?
[raspi /]# sudo losetup -f /dev/mmcblk0p1
[raspi /]# sudo losetup -f /dev/mmcblk0p2
[raspi /]# sudo mount -o rw /dev/loop1 /mnt
[raspi /]# sudo mount -o rw /dev/loop0 /mnt/boot
## If you need to mount / update
[raspi /]# sudo chroot /mnt
[raspi /]# sudo mount -t proc /proc proc/
[raspi /]# sudo mount --rbind /sys sys/
[raspi /]# sudo mount --rbind /dev dev/
## Docker's overlay2 needs to be a tmpfs - Skipped for now
Docker wants to do some mambo-jumbo inside and does not want overlay, need tmpfs
sudo mount -t tmpfs tmpfs /var/lib/docker
need to copy contents of overlay2?
sudo mount -t tmpfs tmpfs /var/lib/docker
sudo cp -r /mnt/var/lib/docker /var/lib/
cp -r /var/lib/docker/* /mnt/var/lib/docker
# Results:
RO FS:
pi@raspberrypi:~ $ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/root 15G 1.5G 13G 11% /
devtmpfs 430M 0 430M 0% /dev
tmpfs 463M 0 463M 0% /dev/shm
tmpfs 463M 6.2M 456M 2% /run
tmpfs 5.0M 4.0K 5.0M 1% /run/lock
tmpfs 463M 0 463M 0% /sys/fs/cgroup
/dev/mmcblk0p1 253M 48M 205M 19% /boot
tmpfs 93M 0 93M 0% /run/user/1000
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