partitioning: Set correct partition type UUID for root filesystem

Previously, only the type "Generic Linux filesystem" was used.
Use the correct type "Linux root ($ARCHITECTURE)" for the root filesystem.

config/sources/amd64.conf

@@ -12,6 +12,11 @@ declare -g ARCH='amd64'                     # Debian name $(dpkg-architecture -q
 declare -g ARCHITECTURE='x86_64'            # "kernel" arch
 declare -g KERNEL_SRC_ARCH='x86'            # kernel SRC_ARCH; there's two for x86_64
 declare -g QEMU_BINARY='qemu-x86_64-static' # Hopefully you have this installed.
+
+# Linux root has a different Type-UUID for every architecture
+# See https://uapi-group.org/specifications/specs/discoverable_partitions_specification/
+declare -g PARTITION_TYPE_UUID_ROOT="4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709" # "Linux root (x86-64)"
+
 declare -g MAIN_CMDLINE=''                  # we set it in common, it was not set before
 declare -g KERNEL_COMPILER=' '              # hack: use single space for host gcc. won't work on arm64 hosts
 declare -g KERNEL_USE_GCC=' '               # more hacks.

config/sources/arm64.conf

@@ -13,6 +13,10 @@ declare -g ARCHITECTURE='arm64'
 declare -g KERNEL_SRC_ARCH='arm64'
 declare -g QEMU_BINARY='qemu-aarch64-static'
 
+# Linux root has a different Type-UUID for every architecture
+# See https://uapi-group.org/specifications/specs/discoverable_partitions_specification/
+declare -g PARTITION_TYPE_UUID_ROOT="B921B045-1DF0-41C3-AF44-4C6F280D3FAE" # "Linux root (ARM-64)"
+
 # Defaults, if not set by board or family.
 declare -g KERNEL_IMAGE_TYPE="${KERNEL_IMAGE_TYPE:-"Image"}"
 declare -g KERNEL_INSTALL_TYPE="${KERNEL_INSTALL_TYPE:-"install"}"

config/sources/armhf.conf

@@ -14,6 +14,10 @@ declare -g KERNEL_SRC_ARCH='arm'
 declare -g QEMU_BINARY='qemu-arm-static'
 declare -g INITRD_ARCH='arm'
 
+# Linux root has a different Type-UUID for every architecture
+# See https://uapi-group.org/specifications/specs/discoverable_partitions_specification/
+declare -g PARTITION_TYPE_UUID_ROOT="69DAD710-2CE4-4E3C-B16C-21A1D49ABED3" # "Linux root (ARM)"
+
 # Defaults, if not set by board or family.
 declare -g KERNEL_IMAGE_TYPE="${KERNEL_IMAGE_TYPE:-"zImage"}"
 declare -g KERNEL_INSTALL_TYPE="${KERNEL_INSTALL_TYPE:-"zinstall"}"

config/sources/riscv64.conf

@@ -15,6 +15,10 @@ declare -g QEMU_BINARY='qemu-riscv64-static'
 declare -g IMAGE_PARTITION_TABLE='gpt'
 declare -g SKIP_EXTERNAL_TOOLCHAINS='yes'
 
+# Linux root has a different Type-UUID for every architecture
+# See https://uapi-group.org/specifications/specs/discoverable_partitions_specification/
+declare -g PARTITION_TYPE_UUID_ROOT="72EC70A6-CF74-40E6-BD49-4BDA08E8F224" # "Linux root (RISC-V-64)"
+
 # Defaults, if not set by board or family.
 declare -g KERNEL_IMAGE_TYPE="${KERNEL_IMAGE_TYPE:-"Image"}"
 declare -g KERNEL_INSTALL_TYPE="${KERNEL_INSTALL_TYPE:-"install"}"

lib/functions/image/partitioning.sh

@@ -214,17 +214,28 @@ function prepare_partitions() {
 						echo "$bootpart : name=\"bootfs\", start=${next}MiB, size=${BOOTSIZE}MiB, type=${type}"
 						local next=$(($next + $BOOTSIZE))
 					else
-						# no `size` argument mean "as much as possible"
+						# No 'size' argument means "expand as much as possible"
 						echo "$bootpart : name=\"bootfs\", start=${next}MiB, type=${type}"
 					fi
 				fi
 
 				# Root filesystem partition
 				if [[ -n "$rootpart" ]]; then
 					# dos: Linux
-					# gpt: Linux filesystem
-					[[ "$IMAGE_PARTITION_TABLE" != "gpt" ]] && local type="83" || local type="0FC63DAF-8483-4772-8E79-3D69D8477DE4"
-					# no `size` argument mean "as much as possible"
+					# gpt: Linux root
+					if [[ "$IMAGE_PARTITION_TABLE" != "gpt" ]]; then
+						local type="83"
+					else
+						# Linux root has a different Type-UUID for every architecture
+						# See https://uapi-group.org/specifications/specs/discoverable_partitions_specification/
+						# The ${PARTITION_TYPE_UUID_ROOT} variable is defined in each architecture file (e.g. config/sources/arm64.conf)
+						if [[ -n "${PARTITION_TYPE_UUID_ROOT}" ]]; then
+							local type="${PARTITION_TYPE_UUID_ROOT}"
+						else
+							exit_with_error "Missing 'PARTITION_TYPE_UUID_ROOT' variable while partitioning the root filesystem!"
+						fi
+					fi
+					# No 'size' argument means "expand as much as possible"
 					echo "$rootpart : name=\"rootfs\", start=${next}MiB, type=${type}"
 				fi
 			}