configs/pc_x86_64_efi: use genimage GPT partition table support

Thanks to the introduction of GPT partition table support in genimage,
this commit improves the pc_x86_64_efi_defconfig to remove the use of
the custom script creating the image.

Tested in QEMU, not on a physical device.

So:
- revert commit fee29b05bb7db25e37c8a5175ce00dc712554edf[1]
- add GPT support
- tweak shell script to add the correct UUID in genimage config.

[1]: https://git.buildroot.net/buildroot/commit/?id=fee29b05bb7db25e37c8a5175ce00dc712554edf
[2]: https://git.buildroot.net/buildroot/commit/?id=79b8540d624ac4846ba341b1b9691eccacf0bc05

Signed-off-by: Alexandre PAYEN <alexandre.payen@smile.fr>
Cc: Carlos Santos <casantos@datacom.com.br>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
[Thomas:
 - drop commented code in post-build.sh
 - take into account comments made by Carlos Santos in
   http://patchwork.ozlabs.org/patch/1143502/]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

board/pc/genimage-efi.cfg

@@ -0,0 +1,35 @@
+image efi-part.vfat {
+  vfat {
+    file startup.nsh {
+      image = "efi-part/startup.nsh"
+    }
+    file EFI {
+      image = "efi-part/EFI"
+    }
+    file bzImage {
+      image = "bzImage"
+    }
+  }
+  size = 16777216
+}
+
+image disk.img {
+  hdimage {
+    gpt = true
+  }
+
+  partition boot {
+    image = "efi-part.vfat"
+    partition-type-uuid = c12a7328-f81f-11d2-ba4b-00a0c93ec93b
+    offset = 32768
+    size = 16777216
+    bootable = true
+  }
+
+  partition root {
+    partition-type-uuid = 44479540-f297-41b2-9af7-d131d5f0458a
+    partition-uuid = UUID_TMP
+    image = "rootfs.ext2"
+    offset = 16809984
+  }
+}

board/pc/grub-efi.cfg

@@ -0,0 +1,6 @@
+set default="0"
+set timeout="5"
+
+menuentry "Buildroot" {
+ linux /bzImage root=PARTUUID=UUID_TMP rootwait console=tty1
+}

board/pc/post-build.sh

@@ -4,7 +4,12 @@ set -e
 
 BOARD_DIR=$(dirname "$0")
 
-cp -f "$BOARD_DIR/grub-bios.cfg" "$TARGET_DIR/boot/grub/grub.cfg"
+# Detect boot strategy, EFI or BIOS
+if [ -f "$BINARIES_DIR/efi-part/startup.nsh" ]; then
+    cp -f "$BOARD_DIR/grub-efi.cfg" "$BINARIES_DIR/efi-part/EFI/BOOT/grub.cfg"
+else
+    cp -f "$BOARD_DIR/grub-bios.cfg" "$TARGET_DIR/boot/grub/grub.cfg"
 
-# Copy grub 1st stage to binaries, required for genimage
-cp -f "$HOST_DIR/lib/grub/i386-pc/boot.img" "$BINARIES_DIR"
+    # Copy grub 1st stage to binaries, required for genimage
+    cp -f "$HOST_DIR/lib/grub/i387-pc/boot.img" "$BINARIES_DIR"
+fi

board/pc/post-image-efi-gpt.sh

@@ -1,62 +0,0 @@
-#!/bin/sh
-
-set -e
-
-cd ${BINARIES_DIR}
-
-# GPT partition type UUIDs
-esp_type=c12a7328-f81f-11d2-ba4b-00a0c93ec93b
-linux_type=44479540-f297-41b2-9af7-d131d5f0458a
-
-# Partition UUIDs
-efi_part_uuid=$(uuidgen)
-root_part_uuid=$(uuidgen)
-
-# Boot partition offset and size, in 512-byte sectors
-efi_part_start=64
-efi_part_size=32768
-
-# Rootfs partition offset and size, in 512-byte sectors
-root_part_start=$(( efi_part_start + efi_part_size ))
-root_part_size=$(( $(stat -c %s rootfs.ext2) / 512 ))
-
-first_lba=34
-last_lba=$(( root_part_start + root_part_size ))
-
-# Disk image size in 512-byte sectors
-image_size=$(( last_lba + first_lba ))
-
-cat > efi-part/EFI/BOOT/grub.cfg <<EOF
-set default="0"
-set timeout="5"
-
-menuentry "Buildroot" {
-	linux /bzImage root=PARTUUID=$root_part_uuid rootwait console=tty1
-}
-EOF
-
-# Create EFI system partition
-rm -f efi-part.vfat
-dd if=/dev/zero of=efi-part.vfat bs=512 count=0 seek=$efi_part_size
-mkdosfs  efi-part.vfat
-mcopy -bsp -i efi-part.vfat efi-part/startup.nsh ::startup.nsh
-mcopy -bsp -i efi-part.vfat efi-part/EFI ::EFI
-mcopy -bsp -i efi-part.vfat bzImage ::bzImage
-
-rm -f disk.img
-dd if=/dev/zero of=disk.img bs=512 count=0 seek=$image_size
-
-sfdisk disk.img <<EOF
-label: gpt
-label-id: $(uuidgen)
-device: /dev/foobar0
-unit: sectors
-first-lba: $first_lba
-last-lba: $last_lba
-
-/dev/foobar0p1 : start=$efi_part_start,  size=$efi_part_size,  type=$esp_type,   uuid=$efi_part_uuid,  name="efi-part.vfat"
-/dev/foobar0p2 : start=$root_part_start, size=$root_part_size, type=$linux_type, uuid=$root_part_uuid, name="rootfs.ext2"
-EOF
-
-dd if=efi-part.vfat of=disk.img bs=512 count=$efi_part_size seek=$efi_part_start conv=notrunc
-dd if=rootfs.ext2   of=disk.img bs=512 count=$root_part_size seek=$root_part_start conv=notrunc

board/pc/post-image-efi.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+UUID=$(dumpe2fs "$BINARIES_DIR/rootfs.ext2" 2>/dev/null | sed -n 's/^Filesystem UUID: *\(.*\)/\1/p')
+sed -i "s/UUID_TMP/$UUID/g" "$BINARIES_DIR/efi-part/EFI/BOOT/grub.cfg"
+sed "s/UUID_TMP/$UUID/g" board/pc/genimage-efi.cfg > "$BINARIES_DIR/genimage-efi.cfg"
+support/scripts/genimage.sh -c "$BINARIES_DIR/genimage-efi.cfg"

configs/pc_x86_64_efi_defconfig

@@ -10,6 +10,7 @@ BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_EUDEV=y
 
 # Required tools to create bootable media
 BR2_PACKAGE_HOST_DOSFSTOOLS=y
+BR2_PACKAGE_HOST_GENIMAGE=y
 BR2_PACKAGE_HOST_MTOOLS=y
 
 # Bootloader
@@ -21,7 +22,8 @@ BR2_TARGET_ROOTFS_EXT2=y
 BR2_TARGET_ROOTFS_EXT2_4=y
 BR2_TARGET_ROOTFS_EXT2_SIZE="120M"
 # BR2_TARGET_ROOTFS_TAR is not set
-BR2_ROOTFS_POST_IMAGE_SCRIPT="board/pc/post-image-efi-gpt.sh"
+BR2_ROOTFS_POST_BUILD_SCRIPT="board/pc/post-build.sh"
+BR2_ROOTFS_POST_IMAGE_SCRIPT="board/pc/post-image-efi.sh"
 
 # Linux headers same as kernel, a 4.18 series
 BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_18=y