Implement A/B switch when moving back to Barebox (#1794)

* Implement manual boot switch when downgrading to Barebox

When installing OS 7 or older from a OS 8 installation, the bootloader
is changed back to Barebox. However, in this case Barebox does not know
which boot slot is correct (and rauc won't update Barebox' state as it
is configured to work with GRUB in OS 8+).

This implements a poor mans version to switch the boot partition. It
clears Barebox state and deploys one of the two pre-configured default
states, booting either boot slot A or B.

buildroot-external/board/pc/generic-x86-64/hassos-hook.sh

@@ -9,6 +9,8 @@ function hassos_pre_image() {
 
     cp "${BINARIES_DIR}/barebox.bin" "${BOOT_DATA}/EFI/BOOT/BOOTx64.EFI"
     cp "${BR2_EXTERNAL_HASSOS_PATH}/bootloader/barebox-state-efi.dtb" "${BOOT_DATA}/EFI/barebox/state.dtb"
+    cp "${BR2_EXTERNAL_HASSOS_PATH}/bootloader/barebox-state-efi-A.dtb" "${BOOT_DATA}/EFI/barebox/state-A.dtb"
+    cp "${BR2_EXTERNAL_HASSOS_PATH}/bootloader/barebox-state-efi-B.dtb" "${BOOT_DATA}/EFI/barebox/state-B.dtb"
     cp "${BOARD_DIR}/cmdline.txt" "${BOOT_DATA}/cmdline.txt"
 }
 

buildroot-external/board/pc/ova/hassos-hook.sh

@@ -9,6 +9,8 @@ function hassos_pre_image() {
 
     cp "${BINARIES_DIR}/barebox.bin" "${BOOT_DATA}/EFI/BOOT/BOOTx64.EFI"
     cp "${BR2_EXTERNAL_HASSOS_PATH}/bootloader/barebox-state-efi.dtb" "${BOOT_DATA}/EFI/barebox/state.dtb"
+    cp "${BR2_EXTERNAL_HASSOS_PATH}/bootloader/barebox-state-efi-A.dtb" "${BOOT_DATA}/EFI/barebox/state-A.dtb"
+    cp "${BR2_EXTERNAL_HASSOS_PATH}/bootloader/barebox-state-efi-B.dtb" "${BOOT_DATA}/EFI/barebox/state-B.dtb"
     cp "${BOARD_DIR}/cmdline.txt" "${BOOT_DATA}/cmdline.txt"
 }
 

buildroot-external/bootloader/barebox-state-efi-A.dts

@@ -0,0 +1,76 @@
+/dts-v1/;
+/ {
+
+	aliases {
+		state = &state;
+	};
+
+	state: state {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		
+		magic = <0xef98423f>;
+		compatible = "barebox,state";
+		backend = <&backend_state>;
+		backend-type = "raw";
+		backend-stridesize = <4048>;
+
+		bootstate {
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			A {
+				#address-cells = <1>;
+				#size-cells = <1>;
+				remaining_attempts@0 {
+					reg = <0x0 0x4>;
+					type = "uint32";
+					default = <3>;
+				};
+				priority@4 {
+					reg = <0x4 0x4>;
+					type = "uint32";
+					default = <20>;
+				};
+			};
+
+			B {
+				#address-cells = <1>;
+				#size-cells = <1>;
+				remaining_attempts@8 {
+					reg = <0x8 0x4>;
+					type = "uint32";
+					default = <0>;
+				};
+				priority@c {
+					reg = <0xc 0x4>;
+					type = "uint32";
+					default = <10>;
+				};
+			};
+
+			last_chosen@10 {
+				reg = <0x10 0x4>;
+				type = "uint32";
+			};
+		};
+
+		machine_id@14 {
+			reg = <0x14 0x24>;
+			type = "string";
+			default = "";
+		};
+	};
+
+	partitions {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "fixed-partitions";
+
+		backend_state: state {
+			partuuid = "33236519-7f32-4dff-8002-3390b62c309d";
+		};
+	};
+
+};
+

buildroot-external/bootloader/barebox-state-efi-B.dts

@@ -0,0 +1,76 @@
+/dts-v1/;
+/ {
+
+	aliases {
+		state = &state;
+	};
+
+	state: state {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		
+		magic = <0xef98423f>;
+		compatible = "barebox,state";
+		backend = <&backend_state>;
+		backend-type = "raw";
+		backend-stridesize = <4048>;
+
+		bootstate {
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			A {
+				#address-cells = <1>;
+				#size-cells = <1>;
+				remaining_attempts@0 {
+					reg = <0x0 0x4>;
+					type = "uint32";
+					default = <3>;
+				};
+				priority@4 {
+					reg = <0x4 0x4>;
+					type = "uint32";
+					default = <10>;
+				};
+			};
+
+			B {
+				#address-cells = <1>;
+				#size-cells = <1>;
+				remaining_attempts@8 {
+					reg = <0x8 0x4>;
+					type = "uint32";
+					default = <3>;
+				};
+				priority@c {
+					reg = <0xc 0x4>;
+					type = "uint32";
+					default = <20>;
+				};
+			};
+
+			last_chosen@10 {
+				reg = <0x10 0x4>;
+				type = "uint32";
+			};
+		};
+
+		machine_id@14 {
+			reg = <0x14 0x24>;
+			type = "string";
+			default = "";
+		};
+	};
+
+	partitions {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "fixed-partitions";
+
+		backend_state: state {
+			partuuid = "33236519-7f32-4dff-8002-3390b62c309d";
+		};
+	};
+
+};
+

buildroot-external/ota/rauc-hook

@@ -28,6 +28,25 @@ case "$1" in
     slot-install)
         # Use install handlers below
         ;;
+    slot-post-install)
+        # Handle main slot only
+        test "${RAUC_SLOT_CLASS}" = "kernel" || exit 0
+
+        BOOT_MNT=/mnt/boot
+
+        if ! systemctl -q is-active mnt-boot.mount; then
+            systemctl start mnt-boot.mount
+        fi
+
+        # OS 8+ to 7 and lower downgrade path
+        if ! command -v barebox-state > /dev/null; then
+            cp -f "${BOOT_MNT}/EFI/barebox/state-${RAUC_SLOT_BOOTNAME}.dtb" "${BOOT_MNT}"/EFI/barebox/state.dtb
+            blkdiscard /dev/disk/by-partuuid/33236519-7f32-4dff-8002-3390b62c309d
+            echo "Cleared state and copied default state-${RAUC_SLOT_BOOTNAME}.dtb to state.dtb."
+        fi
+
+        exit 0
+        ;;
     *)
         exit 1
         ;;

buildroot-external/scripts/ota.sh

@@ -38,6 +38,9 @@ function create_ota_update() {
         echo "hooks=install"
         echo "[image.kernel]"
         echo "filename=kernel.img"
+        if [ "${BOOTLOADER}" == "barebox" ]; then
+            echo "hooks=post-install"
+        fi
         echo "[image.rootfs]"
         echo "filename=rootfs.img"
     ) > "${rauc_folder}/manifest.raucm"