Show page

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 [2026/07/16 14:36] (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:deb-rauc-lab-skel-2026.tar.gz|Download here the starter archive}} containing starter (skeleton) files & scripts.
-**The scripts are templates** — you may need to complete missing parts (search for ''TODO''s)!
+Extract it somewhere in your base working directory.
-=== 2.1. Install Debian into an empty directory ===
+The code structure should be similar to this:
-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>
--rw-r--r--  1 root  root  148M 2025-08-07 14:23 debrootfs.tar.gz
+arm-summer-school/
+├── staging/         # you should have this from lab02
+│   ├── linux-*.its  # Two variants of Linux uImage source descriptors
+│   ├── Makefile     # a Makefile to build linux.itb (finally!)
+│   └── Image,imx93-11x11-frdm.dtb,rootfs.cpio   # copied by the Makefile
+├── rauc-utils/      # RAUC installation 'package'!
+│   ├── install.sh       # RAUC installation script (must be ran inside the chroot!)
+│   ├── ca.cert.pem
+│   ├── rauc-mark-good.service
+│   ├── system.conf
+│   └── fstab            # Optional, custom fstab to mount /boot
+├── linux/               # Linux kernel source directory
+├── u-boot/              # u-boot source directory
+├── debian-rootfs/       # will be created by 'mk-debian-rootfs.sh'
+├── Makefile             # Makefile to build flash.bin from labs 1-3 (u-boot mainline!)
+├── newdefault.env       # new/recommended u-boot default environment
+├── uboot-extra.config   # extra config to use (used by Makefile above)
+├── mk-disk-image.sh     # script to build a FAT32 + EXT4 disk image (solved in lab02/03)
+├── mk-disk-image2.sh    # new disk image script, modified to make 2*rootfs+data partitions
+├── mk-debian-rootfs.sh  # script to debootstrap your debian directory
+└── chroot-enter.sh      # utility script to execute commands in your debian rootfs
 </code>
-=== 2.2. Create the base disk image ===
+=== Prerequisites ===
-📄 File: ''10-create-base-disk.sh''
+We will need the static qemu-aarch64 binaries if we're cross-building, since we need to execute Debian install scripts on our native host archivecture (e.g., ''x86_64'').
-Your task:
+First, make sure you have these packages installed (they were already installed on the VM, so you can skip this):
-  - Use ''truncate'' or ''dd'' to allocate the image with the desired size;
+<code bash>
-  - Modify the ''parted'' invocation (script);
+sudo apt install qemu-user-static binfmt-support debootstrap parted dosfstools e2fsprogs u-boot-tools
-  - Add partitions for:
+</code>
-    - 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]]!