handle being on an arm64 system

README.md

@@ -0,0 +1,65 @@
+# toes-image-builder
+
+Builds a Raspberry Pi Ubuntu Server image for Toes hardware.
+
+## What it does
+
+`build.sh` starts from the Ubuntu 24.04.4 preinstalled ARM64 Raspberry Pi image, mounts it locally, chroots into it, and installs/configures:
+
+- Toes app and systemd service
+- Matter service
+- audio overlay, ALSA config, and audio init service
+- Wi-Fi via `wpa_supplicant` and `systemd-networkd`
+- Bluetooth/Avahi support
+- SSH password login
+- USB serial gadget login
+
+## Requirements
+
+Run on an Ubuntu/Debian host with `sudo` access. On non-ARM64 hosts, the build expects `qemu-aarch64` binfmt support.
+
+Bootstrap the host once:
+
+```sh
+scripts/bootstrap-repo.sh
+```
+
+## Build
+
+```sh
+./build.sh
+```
+
+The script downloads the base image into `cache/`, writes build artifacts into `build/`, mounts the image under `mnt/`, and cleans up mounts on exit.
+
+Final image path:
+
+```text
+build/toes-ubuntu-base.img
+```
+
+## Default image access
+
+- Hostname: `toes`
+- User: `toes`
+- Password: set by `scripts/build-in-chroot.sh`
+- SSH password auth: enabled
+- USB serial gadget: enabled on `ttyGS0`
+
+## Layout
+
+- `build.sh` - top-level build pipeline
+- `scripts/` - host-side build phases
+- `audio/` - audio overlay, ALSA config, and init service
+- `matter/` - Matter systemd service
+- `cache/` - downloaded Ubuntu image and checksums
+- `build/` - generated image files
+- `mnt/` - temporary mount points
+
+## Cleanup
+
+If a build is interrupted and mounts are left behind, run:
+
+```sh
+scripts/cleanup.sh
+```

scripts/bootstrap-repo.sh

@@ -4,18 +4,26 @@ set -ex
 # bootstrap _this_ repo (toes-image-builder), not the image itself.
 # should only have to do this once per host we run this on.
 
-sudo apt-get update
-sudo apt-get install -y \
-	qemu-user-static \
-	binfmt-support \
-	qemu-system-arm \
-	qemu-utils \
-	kpartx \
-	parted \
-	fdisk \
-	dosfstools \
-	e2fsprogs \
-	xz-utils \
-	rsync \
-	curl \
+packages=(
+	kpartx
+	parted
+	fdisk
+	dosfstools
+	e2fsprogs
+	xz-utils
+	rsync
+	curl
 	ca-certificates
+)
+
+case "$(uname -m)" in
+	aarch64|arm64)
+		echo "native arm64 host detected; skipping qemu user emulation packages"
+		;;
+	*)
+		packages=(qemu-user-static binfmt-support "${packages[@]}")
+		;;
+esac
+
+sudo apt-get update
+sudo apt-get install -y "${packages[@]}"

scripts/build-in-chroot.sh

@@ -1,7 +1,7 @@
 #! /bin/bash
 set -ex
 
-# runs setup commands inside the image, under qemu arm64.
+# runs setup commands inside the arm64 image rootfs.
 
 sudo tee mnt/root/tmp/image-build.sh >/dev/null <<'EOF'
 #! /bin/bash