feat: raspberry pi U-Boot + GPT + btrfs boot chain

Switch Raspberry Pi builds from proprietary firmware direct-boot to a firmware → U-Boot → GRUB → kernel chain using GPT partitioning: - GPT partition layout with fixed UUIDs matching os_install: firmware (128MB), ESP (100MB), boot (2GB FAT32), root (btrfs) - U-Boot as the kernel in config.txt, chainloading GRUB EFI - Pi-specific GRUB config overrides (console, USB quirks, cgroup) - Btrfs root with shrink-to-minimum for image compression - init_resize.sh updated for GPT (sgdisk -e) and btrfs resize - Removed os-partitions from config.yaml (now derived from fstab)
2026-03-26 02:11:53 +00:00 · 2026-03-12 11:12:04 -06:00
parent d12b278a84
commit dba1cb93c1
10 changed files with 130 additions and 66 deletions
--- a/build/dpkg-deps/raspberrypi.depends
+++ b/build/dpkg-deps/raspberrypi.depends
@@ -1,5 +1,6 @@
- grub-efi
+ gdisk
 + parted
+ u-boot-rpi
 + raspberrypi-net-mods
 + raspberrypi-sys-mods
 + raspi-config
--- a/build/image-recipe/Dockerfile
+++ b/build/image-recipe/Dockerfile
@@ -23,6 +23,8 @@ RUN apt-get update && \
    squashfs-tools \
    rsync \
    b3sum \
+    btrfs-progs \
+    gdisk \
    dpkg-dev


--- a/build/image-recipe/build.sh
+++ b/build/image-recipe/build.sh
@@ -132,6 +132,10 @@ ff02::1         ip6-allnodes
 ff02::2         ip6-allrouters
 EOT

+# Installer marker file (used by installed GRUB to detect the live USB)
+mkdir -p config/includes.binary
+touch config/includes.binary/.startos-installer
+
 if [ "${IB_TARGET_PLATFORM}" = "raspberrypi" ]; then
 	mkdir -p config/includes.chroot
 	git clone --depth=1 --branch=stable https://github.com/raspberrypi/rpi-firmware.git config/includes.chroot/boot
@@ -322,9 +326,10 @@ fi

 if [ "${IB_TARGET_PLATFORM}" = "raspberrypi" ]; then
    ln -sf /usr/bin/pi-beep /usr/local/bin/beep
-    KERNEL_VERSION=${RPI_KERNEL_VERSION} sh /boot/config.sh > /boot/config.txt
+    sh /boot/config.sh > /boot/config.txt
    mkinitramfs -c gzip -o /boot/initrd.img-${RPI_KERNEL_VERSION}-rpi-v8 ${RPI_KERNEL_VERSION}-rpi-v8
    mkinitramfs -c gzip -o /boot/initrd.img-${RPI_KERNEL_VERSION}-rpi-2712 ${RPI_KERNEL_VERSION}-rpi-2712
+    cp /usr/lib/u-boot/rpi_arm64/u-boot.bin /boot/u-boot.bin
 fi

 useradd --shell /bin/bash -G startos -m start9
@@ -390,38 +395,65 @@ if [ "${IMAGE_TYPE}" = iso ]; then
 elif [ "${IMAGE_TYPE}" = img ]; then

 	SECTOR_LEN=512
-	BOOT_START=$((1024 * 1024)) # 1MiB
-	BOOT_LEN=$((512 * 1024 * 1024)) # 512MiB
+	FW_START=$((1024 * 1024)) # 1MiB (sector 2048) — Pi-specific
+	FW_LEN=$((128 * 1024 * 1024)) # 128MiB (Pi firmware + U-Boot + DTBs)
+	FW_END=$((FW_START + FW_LEN - 1))
+	ESP_START=$((FW_END + 1)) # 100MB EFI System Partition (matches os_install)
+	ESP_LEN=$((100 * 1024 * 1024))
+	ESP_END=$((ESP_START + ESP_LEN - 1))
+	BOOT_START=$((ESP_END + 1)) # 2GB /boot (matches os_install)
+	BOOT_LEN=$((2 * 1024 * 1024 * 1024))
 	BOOT_END=$((BOOT_START + BOOT_LEN - 1))
 	ROOT_START=$((BOOT_END + 1))
 	ROOT_LEN=$((MAX_IMG_LEN - ROOT_START))
-	ROOT_END=$((MAX_IMG_LEN - 1))
+
+	# Fixed GPT partition UUIDs (deterministic, based on old MBR disk ID cb15ae4d)
+	FW_UUID=cb15ae4d-0001-4000-8000-000000000001
+	ESP_UUID=cb15ae4d-0002-4000-8000-000000000002
+	BOOT_UUID=cb15ae4d-0003-4000-8000-000000000003
+	ROOT_UUID=cb15ae4d-0004-4000-8000-000000000004

 	TARGET_NAME=$prep_results_dir/${IMAGE_BASENAME}.img
 	truncate -s $MAX_IMG_LEN $TARGET_NAME

 	sfdisk $TARGET_NAME <<-EOF
-		label: dos
-		label-id: 0xcb15ae4d
-		unit: sectors
-		sector-size: 512
+		label: gpt

-		${TARGET_NAME}1 : start=$((BOOT_START / SECTOR_LEN)), size=$((BOOT_LEN / SECTOR_LEN)), type=c, bootable
-		${TARGET_NAME}2 : start=$((ROOT_START / SECTOR_LEN)), size=$((ROOT_LEN / SECTOR_LEN)), type=83
+		${TARGET_NAME}1 : start=$((FW_START / SECTOR_LEN)), size=$((FW_LEN / SECTOR_LEN)), type=EBD0A0A2-B9E5-4433-87C0-68B6B72699C7, uuid=${FW_UUID}, name="firmware"
+		${TARGET_NAME}2 : start=$((ESP_START / SECTOR_LEN)), size=$((ESP_LEN / SECTOR_LEN)), type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, uuid=${ESP_UUID}, name="efi"
+		${TARGET_NAME}3 : start=$((BOOT_START / SECTOR_LEN)), size=$((BOOT_LEN / SECTOR_LEN)), type=0FC63DAF-8483-4772-8E79-3D69D8477DE4, uuid=${BOOT_UUID}, name="boot"
+		${TARGET_NAME}4 : start=$((ROOT_START / SECTOR_LEN)), size=$((ROOT_LEN / SECTOR_LEN)), type=B921B045-1DF0-41C3-AF44-4C6F280D3FAE, uuid=${ROOT_UUID}, name="root"
 	EOF

+	FW_DEV=$(losetup --show -f --offset $FW_START --sizelimit $FW_LEN $TARGET_NAME)
+	ESP_DEV=$(losetup --show -f --offset $ESP_START --sizelimit $ESP_LEN $TARGET_NAME)
 	BOOT_DEV=$(losetup --show -f --offset $BOOT_START --sizelimit $BOOT_LEN $TARGET_NAME)
 	ROOT_DEV=$(losetup --show -f --offset $ROOT_START --sizelimit $ROOT_LEN $TARGET_NAME)

-	mkfs.vfat -F32 $BOOT_DEV
-	mkfs.ext4 $ROOT_DEV
+	mkfs.vfat -F32 -n firmware $FW_DEV
+	mkfs.vfat -F32 -n efi $ESP_DEV
+	mkfs.vfat -F32 -n boot $BOOT_DEV
+	mkfs.btrfs -f -L rootfs $ROOT_DEV

 	TMPDIR=$(mktemp -d)

-	mkdir -p $TMPDIR/boot $TMPDIR/root
-	mount $ROOT_DEV $TMPDIR/root
+	# Extract boot files from squashfs to staging area
+	BOOT_STAGING=$(mktemp -d)
+	unsquashfs -n -f -d $BOOT_STAGING $prep_results_dir/binary/live/filesystem.squashfs boot
+
+	# Mount partitions
+	mkdir -p $TMPDIR/firmware $TMPDIR/efi $TMPDIR/boot $TMPDIR/root
+	mount $FW_DEV $TMPDIR/firmware
+	mount $ESP_DEV $TMPDIR/efi
 	mount $BOOT_DEV $TMPDIR/boot
-	unsquashfs -n -f -d $TMPDIR $prep_results_dir/binary/live/filesystem.squashfs boot
+	mount $ROOT_DEV $TMPDIR/root
+
+	# Split boot files: firmware to Part 1, kernels/initramfs to Part 3 (/boot)
+	cp -a $BOOT_STAGING/boot/. $TMPDIR/firmware/
+	for f in $TMPDIR/firmware/vmlinuz-* $TMPDIR/firmware/initrd.img-* $TMPDIR/firmware/System.map-* $TMPDIR/firmware/config-*; do
+		[ -e "$f" ] && mv "$f" $TMPDIR/boot/
+	done
+	rm -rf $BOOT_STAGING

 	mkdir $TMPDIR/root/images $TMPDIR/root/config
 	B3SUM=$(b3sum $prep_results_dir/binary/live/filesystem.squashfs | head -c 16)
@@ -434,40 +466,73 @@ elif [ "${IMAGE_TYPE}" = img ]; then
 	mount -t overlay -o lowerdir=$TMPDIR/lower,workdir=$TMPDIR/root/config/work,upperdir=$TMPDIR/root/config/overlay overlay $TMPDIR/next

 	if [ "${IB_TARGET_PLATFORM}" = "raspberrypi" ]; then
-		sed -i 's| boot=startos| boot=startos init=/usr/lib/startos/scripts/init_resize\.sh|' $TMPDIR/boot/cmdline.txt
 		rsync -a $SOURCE_DIR/raspberrypi/img/ $TMPDIR/next/
+
+		# Install GRUB: ESP at /boot/efi (Part 2), /boot (Part 3)
+		mkdir -p $TMPDIR/next/boot $TMPDIR/next/boot/efi $TMPDIR/next/boot/firmware \
+			$TMPDIR/next/dev $TMPDIR/next/proc $TMPDIR/next/sys $TMPDIR/next/media/startos/root
+		mount --bind $TMPDIR/boot $TMPDIR/next/boot
+		mount --bind $TMPDIR/efi $TMPDIR/next/boot/efi
+		mount --bind $TMPDIR/firmware $TMPDIR/next/boot/firmware
+		mount --bind /dev $TMPDIR/next/dev
+		mount --bind /proc $TMPDIR/next/proc
+		mount --bind /sys $TMPDIR/next/sys
+		mount --bind $TMPDIR/root $TMPDIR/next/media/startos/root
+
+		chroot $TMPDIR/next grub-install --target=arm64-efi --removable --efi-directory=/boot/efi --boot-directory=/boot --no-nvram
+		chroot $TMPDIR/next update-grub
+
+		umount $TMPDIR/next/media/startos/root
+		umount $TMPDIR/next/sys
+		umount $TMPDIR/next/proc
+		umount $TMPDIR/next/dev
+		umount $TMPDIR/next/boot/firmware
+		umount $TMPDIR/next/boot/efi
+		umount $TMPDIR/next/boot
+
+		# Fix root= in grub.cfg: update-grub sees loop devices, but the
+		# real device uses a fixed GPT PARTUUID for root (Part 4).
+		sed -i "s|root=[^ ]*|root=PARTUUID=${ROOT_UUID}|g" $TMPDIR/boot/grub/grub.cfg
+
+		# Inject first-boot resize script into GRUB config
+		sed -i 's| boot=startos| boot=startos init=/usr/lib/startos/scripts/init_resize\.sh|' $TMPDIR/boot/grub/grub.cfg
 	fi

 	umount $TMPDIR/next
 	umount $TMPDIR/lower

+	umount $TMPDIR/firmware
+	umount $TMPDIR/efi
 	umount $TMPDIR/boot
 	umount $TMPDIR/root

-
-	e2fsck -fy $ROOT_DEV
-	resize2fs -M $ROOT_DEV
-
-	BLOCK_COUNT=$(dumpe2fs -h $ROOT_DEV | awk '/^Block count:/ { print $3 }')
-	BLOCK_SIZE=$(dumpe2fs -h $ROOT_DEV | awk '/^Block size:/ { print $3 }')
-	ROOT_LEN=$((BLOCK_COUNT * BLOCK_SIZE))
+	# Shrink btrfs to minimum size
+	SHRINK_MNT=$(mktemp -d)
+	mount $ROOT_DEV $SHRINK_MNT
+	btrfs filesystem resize min $SHRINK_MNT
+	umount $SHRINK_MNT
+	rmdir $SHRINK_MNT
+	ROOT_LEN=$(btrfs inspect-internal dump-super $ROOT_DEV | awk '/^total_bytes/ {print $2}')

 	losetup -d $ROOT_DEV
 	losetup -d $BOOT_DEV
+	losetup -d $ESP_DEV
+	losetup -d $FW_DEV

-	# Recreate partition 2 with the new size using sfdisk
+	# Recreate partition table with shrunk root
 	sfdisk $TARGET_NAME <<-EOF
-		label: dos
-		label-id: 0xcb15ae4d
-		unit: sectors
-		sector-size: 512
+		label: gpt

-		${TARGET_NAME}1 : start=$((BOOT_START / SECTOR_LEN)), size=$((BOOT_LEN / SECTOR_LEN)), type=c, bootable
-		${TARGET_NAME}2 : start=$((ROOT_START / SECTOR_LEN)), size=$((ROOT_LEN / SECTOR_LEN)), type=83
+		${TARGET_NAME}1 : start=$((FW_START / SECTOR_LEN)), size=$((FW_LEN / SECTOR_LEN)), type=EBD0A0A2-B9E5-4433-87C0-68B6B72699C7, uuid=${FW_UUID}, name="firmware"
+		${TARGET_NAME}2 : start=$((ESP_START / SECTOR_LEN)), size=$((ESP_LEN / SECTOR_LEN)), type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, uuid=${ESP_UUID}, name="efi"
+		${TARGET_NAME}3 : start=$((BOOT_START / SECTOR_LEN)), size=$((BOOT_LEN / SECTOR_LEN)), type=0FC63DAF-8483-4772-8E79-3D69D8477DE4, uuid=${BOOT_UUID}, name="boot"
+		${TARGET_NAME}4 : start=$((ROOT_START / SECTOR_LEN)), size=$((ROOT_LEN / SECTOR_LEN)), type=B921B045-1DF0-41C3-AF44-4C6F280D3FAE, uuid=${ROOT_UUID}, name="root"
 	EOF

 	TARGET_SIZE=$((ROOT_START + ROOT_LEN))
 	truncate -s $TARGET_SIZE $TARGET_NAME
+	# Move backup GPT to new end of disk after truncation
+	sgdisk -e $TARGET_NAME

 	mv $TARGET_NAME $RESULTS_DIR/$IMAGE_BASENAME.img

--- a/build/image-recipe/raspberrypi/img/etc/fstab
+++ b/build/image-recipe/raspberrypi/img/etc/fstab
@@ -1,2 +1,4 @@
-/dev/mmcblk0p1  /boot   vfat    umask=0077  0   2
-/dev/mmcblk0p2  /       ext4    defaults    0   1
+PARTUUID=cb15ae4d-0001-4000-8000-000000000001  /boot/firmware  vfat    umask=0077  0   2
+PARTUUID=cb15ae4d-0002-4000-8000-000000000002  /boot/efi       vfat    umask=0077  0   1
+PARTUUID=cb15ae4d-0003-4000-8000-000000000003  /boot           vfat    umask=0077  0   2
+PARTUUID=cb15ae4d-0004-4000-8000-000000000004  /               btrfs   defaults    0   1
--- a/build/image-recipe/raspberrypi/img/usr/lib/startos/scripts/init_resize.sh
+++ b/build/image-recipe/raspberrypi/img/usr/lib/startos/scripts/init_resize.sh
@@ -12,15 +12,16 @@ get_variables () {
  BOOT_DEV_NAME=$(echo /sys/block/*/"${BOOT_PART_NAME}" | cut -d "/" -f 4)
  BOOT_PART_NUM=$(cat "/sys/block/${BOOT_DEV_NAME}/${BOOT_PART_NAME}/partition")

-  OLD_DISKID=$(fdisk -l "$ROOT_DEV" | sed -n 's/Disk identifier: 0x\([^ ]*\)/\1/p')
-
  ROOT_DEV_SIZE=$(cat "/sys/block/${ROOT_DEV_NAME}/size")
-  if [ "$ROOT_DEV_SIZE" -le 67108864 ]; then
-      TARGET_END=$((ROOT_DEV_SIZE - 1))
+  # GPT backup header/entries occupy last 33 sectors
+  USABLE_END=$((ROOT_DEV_SIZE - 34))
+
+  if [ "$USABLE_END" -le 67108864 ]; then
+      TARGET_END=$USABLE_END
  else
      TARGET_END=$((33554432 - 1))
      DATA_PART_START=33554432
-      DATA_PART_END=$((ROOT_DEV_SIZE - 1))
+      DATA_PART_END=$USABLE_END
  fi

  PARTITION_TABLE=$(parted -m "$ROOT_DEV" unit s print | tr -d 's')
@@ -61,33 +62,24 @@ main () {
    return 1
  fi

-#   if [ "$ROOT_PART_END" -eq "$TARGET_END" ]; then
-#     reboot_pi
-#   fi
-
  if ! echo Yes | parted -m --align=optimal "$ROOT_DEV" ---pretend-input-tty u s resizepart "$ROOT_PART_NUM" "$TARGET_END" ; then
    FAIL_REASON="Root partition resize failed"
    return 1
  fi

  if [ -n "$DATA_PART_START" ]; then
-    if ! parted -ms --align=optimal "$ROOT_DEV" u s mkpart primary "$DATA_PART_START" "$DATA_PART_END"; then
+    if ! parted -ms --align=optimal "$ROOT_DEV" u s mkpart data "$DATA_PART_START" "$DATA_PART_END"; then
      FAIL_REASON="Data partition creation failed"
      return 1
    fi
  fi

-  (
-    echo x
-    echo i
-    echo "0xcb15ae4d"
-    echo r
-    echo w
-  ) | fdisk $ROOT_DEV
+  # Fix GPT backup header to reflect new partition layout
+  sgdisk -e "$ROOT_DEV" 2>/dev/null || true

  mount / -o remount,rw

-  resize2fs $ROOT_PART_DEV
+  btrfs filesystem resize max /media/startos/root

  if ! systemd-machine-id-setup --root=/media/startos/config/overlay/; then
    FAIL_REASON="systemd-machine-id-setup failed"
@@ -111,7 +103,7 @@ mount / -o remount,ro
 beep

 if main; then
-  sed -i 's| init=/usr/lib/startos/scripts/init_resize\.sh||' /boot/cmdline.txt
+  sed -i 's| init=/usr/lib/startos/scripts/init_resize\.sh||' /boot/grub/grub.cfg
  echo "Resized root filesystem. Rebooting in 5 seconds..."
  sleep 5
 else
--- a/build/image-recipe/raspberrypi/squashfs/boot/cmdline.txt
+++ b/build/image-recipe/raspberrypi/squashfs/boot/cmdline.txt
@@ -1 +0,0 @@
-usb-storage.quirks=152d:0562:u,14cd:121c:u,0781:cfcb:u console=serial0,115200 console=tty1 root=PARTUUID=cb15ae4d-02 rootfstype=ext4 fsck.repair=yes rootwait cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory boot=startos
--- a/build/image-recipe/raspberrypi/squashfs/boot/config.sh
+++ b/build/image-recipe/raspberrypi/squashfs/boot/config.sh
@@ -27,20 +27,18 @@ disable_overscan=1
 # (e.g. for USB device mode) or if USB support is not required.
 otg_mode=1

-[all]
-
 [pi4]
 # Run as fast as firmware / board allows
 arm_boost=1
-kernel=vmlinuz-${KERNEL_VERSION}-rpi-v8
-initramfs initrd.img-${KERNEL_VERSION}-rpi-v8 followkernel
-
-[pi5]
-kernel=vmlinuz-${KERNEL_VERSION}-rpi-2712
-initramfs initrd.img-${KERNEL_VERSION}-rpi-2712 followkernel

 [all]
 gpu_mem=16
 dtoverlay=pwm-2chan,disable-bt

+# Enable UART for U-Boot and serial console
+enable_uart=1
+
+# Load U-Boot as the bootloader (GRUB is chainloaded from U-Boot)
+kernel=u-boot.bin
+
 EOF
--- a/build/image-recipe/raspberrypi/squashfs/boot/config.txt
+++ b/build/image-recipe/raspberrypi/squashfs/boot/config.txt
@@ -84,4 +84,8 @@ arm_boost=1
 gpu_mem=16
 dtoverlay=pwm-2chan,disable-bt

-auto_initramfs=1
+# Enable UART for U-Boot and serial console
+enable_uart=1
+
+# Load U-Boot as the bootloader (GRUB is chainloaded from U-Boot)
+kernel=u-boot.bin
--- a/build/image-recipe/raspberrypi/squashfs/etc/default/grub.d/raspberrypi.cfg
+++ b/build/image-recipe/raspberrypi/squashfs/etc/default/grub.d/raspberrypi.cfg
@@ -0,0 +1,4 @@
+# Raspberry Pi-specific GRUB overrides
+# Overrides GRUB_CMDLINE_LINUX from /etc/default/grub with Pi-specific
+# console devices and hardware quirks.
+GRUB_CMDLINE_LINUX="boot=startos console=serial0,115200 console=tty1 usb-storage.quirks=152d:0562:u,14cd:121c:u,0781:cfcb:u cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory"
--- a/build/image-recipe/raspberrypi/squashfs/etc/startos/config.yaml
+++ b/build/image-recipe/raspberrypi/squashfs/etc/startos/config.yaml
@@ -1,6 +1,3 @@
-os-partitions:
-  boot: /dev/mmcblk0p1
-  root: /dev/mmcblk0p2
 ethernet-interface: end0
 wifi-interface: wlan0
 disable-encryption: true
				`@@ -1 +0,0 @@`
				`usb-storage.quirks=152d:0562:u,14cd:121c:u,0781:cfcb:u console=serial0,115200 console=tty1 root=PARTUUID=cb15ae4d-02 rootfstype=ext4 fsck.repair=yes rootwait cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory boot=startos`