board/stm32f769-disco: move kernel and DTB to rootfs partition

The patch, following the suggestion expressed in the review [1] for the
stm32f746-disco board support, moves the Linux kernel and the related
device tree to the ext4 rootfs partition. By doing so, the vfat partition,
improperly called u-boot, no longer makes sense and can therefore be
removed. From now on, U-Boot will load the kernel and the device tree
from the ext4 rootfs partition.

[1] https://patchwork.ozlabs.org/project/buildroot/patch/20240822183742.3550055-3-dario.binacchi@amarulasolutions.com/

Suggested-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>

board/stmicroelectronics/stm32f769-disco/extlinux.conf

@@ -1,4 +1,4 @@
 label stm32f769-disco-buildroot
-  kernel /zImage
-  devicetree /stm32f769-disco.dtb
-  append console=ttySTM0,115200 root=/dev/mmcblk0p2 rw rootfstype=ext2 rootwait earlyprintk consoleblank=0 ignore_loglevel
+  kernel /boot/zImage
+  devicetree /boot/stm32f769-disco.dtb
+  append console=ttySTM0,115200 root=/dev/mmcblk0p1 rw rootfstype=ext2 rootwait earlyprintk consoleblank=0 ignore_loglevel

board/stmicroelectronics/stm32f769-disco/genimage.cfg

@@ -1,24 +1,7 @@
-image boot.vfat {
-	vfat {
-		files = {
-			"zImage",
-			"stm32f769-disco.dtb",
-			"extlinux"
-		}
-	}
-
-	size = 16M
-}
-
 image sdcard.img {
 	hdimage {
 	}
 
-	partition u-boot {
-		partition-type = 0xC
-		image = "boot.vfat"
-	}
-
 	partition rootfs {
 		partition-type = 0x83
 		image = "rootfs.ext2"

board/stmicroelectronics/stm32f769-disco/post-build.sh

@@ -4,4 +4,4 @@ BOARD_DIR="$(dirname "$0")"
 # Kernel is built without devpts support
 sed -i '/^devpts/d' "${TARGET_DIR}"/etc/fstab
 
-install -m 0644 -D "${BOARD_DIR}"/extlinux.conf "${BINARIES_DIR}"/extlinux/extlinux.conf
+install -m 0644 -D "${BOARD_DIR}"/extlinux.conf "${TARGET_DIR}"/boot/extlinux/extlinux.conf

configs/stm32f769_disco_sd_defconfig

@@ -15,6 +15,7 @@ BR2_LINUX_KERNEL_IMAGE_TARGET_CUSTOM=y
 BR2_LINUX_KERNEL_IMAGE_TARGET_NAME="zImage"
 BR2_LINUX_KERNEL_DTS_SUPPORT=y
 BR2_LINUX_KERNEL_INTREE_DTS_NAME="stm32f769-disco"
+BR2_LINUX_KERNEL_INSTALL_TARGET=y
 # BR2_PACKAGE_IFUPDOWN_SCRIPTS is not set
 BR2_TARGET_ROOTFS_EXT2=y
 BR2_TARGET_ROOTFS_EXT2_SIZE="32M"
@@ -25,7 +26,5 @@ BR2_TARGET_UBOOT_CUSTOM_VERSION=y
 BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2024.07"
 BR2_TARGET_UBOOT_BOARD_DEFCONFIG="stm32f769-disco"
 BR2_TARGET_UBOOT_NEEDS_OPENSSL=y
-BR2_PACKAGE_HOST_DOSFSTOOLS=y
 BR2_PACKAGE_HOST_GENIMAGE=y
-BR2_PACKAGE_HOST_MTOOLS=y
 BR2_PACKAGE_HOST_OPENOCD=y