Differences
This shows you the differences between two versions of the page.
|
ass:labs-2025:04:tasks:01 [2025/08/07 18:10] florin.stancu |
ass:labs-2025:04:tasks:01 [2025/08/07 20:54] (current) florin.stancu |
||
|---|---|---|---|
| Line 1: | Line 1: | ||
| - | ==== 02. Disk image & Debian ==== | + | ==== 01. Preparations ==== |
| - | You’ll be running scripts in ''./scripts'', either one by one or all together via ''./run-all.sh''. | + | {{:ass:labs-2025:04:rauc-lab-skel.tar.gz|Download here the starter archive}} containing skeleton files + scripts. |
| - | **The scripts are templates** — you may need to complete missing parts (search for ''TODO''s)! | + | Extract it somewhere in a new directory (e.g., create ''rauc-lab''). |
| - | === 2.1. Install Debian into an empty directory === | + | The code structure will become (mostly is, but some are TODO) as follows: |
| - | Yes, really, you can easily do this! | ||
| - | |||
| - | You will use the [[https://wiki.debian.org/Debootstrap|debootstrap]] official tool to install a minimal Debian (you can also install deb-based derivatives like Ubuntu!) base system. | ||
| - | |||
| - | 📄 Edit the ''05-debootstrap.sh'' script. | ||
| - | |||
| - | Since we need to install the Debian binaries executable on a 64-bit ARM architecture, we will need to split the installation into two stages: first, the .deb (Debian install packages) are downloaded from a Debian mirror server and unpacked into the target rootfs directory. Afterwards, since Debian will need to run some scripts to setup its distro system, we must **emulate** the target architecture. Enter [[https://www.qemu.org/|qemu]] which will help us to just that! | ||
| - | |||
| - | Finally, we need to obtain the ''artifacts/debrootfs.tar.gz'' archive with the contents of our newly-created Aarch64 Debian. Use ''tar'' to ''c''reate a g''z''ipped archive, and be sure to ''p''reserve permissions! | ||
| - | |||
| - | The final results should be something like: | ||
| <code> | <code> | ||
| - | -rw-r--r-- 1 root root 148M 2025-08-07 14:23 debrootfs.tar.gz | + | rauc-lab/ |
| + | ├── artifacts/ # <-- you'll create this | ||
| + | │ ├── flash_spl.bin # A working flash.bin image you already have | ||
| + | │ ├── flash_emmc.bin # Your new flash.bin (see tasks) | ||
| + | │ ├── linux.itb # A kernel image (after removing the initrd) | ||
| + | │ ├── uboot.env # U-Boot environment variables (just the var file) | ||
| + | ├── utils/ | ||
| + | │ ├── ca.cert.pem | ||
| + | │ ├── rauc-mark-good.service | ||
| + | │ ├── system.conf | ||
| + | │ └── fstab # Optional custom fstab | ||
| + | ├── scripts/ # <-- your main job to finish those! | ||
| + | │ ├── 05-debootstrap.sh | ||
| + | │ ├── 10-create-base-disk.sh | ||
| + | │ ├── 11-populate-disk-image.sh | ||
| + | │ ├── 20-modify-bootcmd.sh | ||
| + | │ ├── 21-install-boot.sh | ||
| + | │ └── 30-install-rauc.sh | ||
| + | ├── run-all.sh # Will run all scripts in order | ||
| </code> | </code> | ||
| - | === 2.2. Create the base disk image === | + | === Prerequisites === |
| - | 📄 File: ''10-create-base-disk.sh'' | + | First, make sure you have these packages installed on your host system (they were already installed on the VM, so you can skip this): |
| - | Your task: | + | <code bash> |
| + | sudo apt install qemu-user-static binfmt-support debootstrap parted dosfstools e2fsprogs u-boot-tools | ||
| + | </code> | ||
| - | - Use ''truncate'' or ''dd'' to allocate the image with the desired size; | ||
| - | - Modify the ''parted'' invocation (script); | ||
| - | - Add partitions for: | ||
| - | - rootfsA (ext4) | ||
| - | - rootfsB (ext4) | ||
| - | - data (ext4) | ||
| - | <note warning> | + | Then, check that ''binfmt_misc'' is active and register the QEMU handler for ''aarch64'': |
| - | Make the partition have the labels documented above (as they are used throughout the RAUC scripts and/or in u-boot)! | + | |
| - | </note> | + | |
| - | === 2.3. Populate the rootfs partitions === | + | <code bash> |
| + | grep aarch64 /proc/sys/fs/binfmt_misc/qemu-aarch64 | ||
| + | </code> | ||
| - | 📄 File: ''25-populate-base-disk.sh'' | + | If it’s empty, run: |
| - | Subtasks: | + | <code bash> |
| - | + | sudo su | |
| - | - Mount the partitions created previously (already in script); | + | echo ':qemu-aarch64:M::\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff:/usr/bin/qemu-aarch64-static:CF' > /proc/sys/fs/binfmt_misc/register |
| - | - Extract the previously-obtained Debian ''debrootfs.tar.gz'' on each rootfs A/B partition (a simple ''tar xf'' will suffice); | + | exit |
| - | + | </code> | |
| - | Note: you will lack ''flash_emmc.bin'' required by this script. So let's proceed without testing, for now. | + | |
| - | + | ||
| - | === Entering the rootfs === | + | |
| - | + | ||
| - | If you wish to enter your newly bootstrapped Debian rootfs, you can use the following script: | + | |
| - | + | ||
| - | <file bash enter-rootfs.sh> | + | |
| - | #!/bin/bash | + | |
| - | set -e | + | |
| - | + | ||
| - | ROOTFS=$1 | + | |
| - | + | ||
| - | if [[ ! -d "$ROOTFS/usr/bin" ]]; then | + | |
| - | echo "[!] Invalid rootfs argument: '$ROOTFS'" | + | |
| - | exit 1 | + | |
| - | fi | + | |
| - | + | ||
| - | cleanup() { | + | |
| - | echo "[*] Cleaning up..." | + | |
| - | for sub in dev/pts dev proc sys run; do | + | |
| - | if mountpoint -q "$ROOTFS/$sub"; then | + | |
| - | echo " Unmounting $ROOTFS/$sub" | + | |
| - | sudo umount "$ROOTFS/$sub" || true | + | |
| - | fi | + | |
| - | done | + | |
| - | } | + | |
| - | trap cleanup EXIT | + | |
| - | + | ||
| - | echo "[+] Binding chroot filesystems..." | + | |
| - | for fs in dev dev/pts proc sys run; do | + | |
| - | sudo mount --bind "/$fs" "$ROOTFS/$fs" | + | |
| - | done | + | |
| - | + | ||
| - | echo "[+] Ensuring /etc/resolv.conf for DNS inside chroot" | + | |
| - | sudo cp /etc/resolv.conf "$ROOTFS/etc/resolv.conf" | + | |
| - | + | ||
| - | echo "[+] Entering your chroot shell..." | + | |
| - | echo "Type exit to leave" | + | |
| - | sudo chroot "$ROOTFS" /usr/bin/qemu-aarch64-static /bin/bash | + | |
| - | </file> | + | |
| - | You can even run ''apt install'' in there ;) | + | For Arch Linux users: check out [[https://wiki.archlinux.org/title/QEMU#Chrooting_into_arm/arm64_environment_from_x86_64|this guide for installable dependencies]]! |
