grub2: add support for arm and aarch64

index 35aea41287..1b366d0407 100644
@@ -9,7 +9,10 @@ GRUB2_SITE = http://ftp.gnu.org/gnu/grub
 GRUB2_SOURCE = grub-$(GRUB2_VERSION).tar.xz
 GRUB2_LICENSE = GPL-3.0+
 GRUB2_LICENSE_FILES = COPYING
-GRUB2_DEPENDENCIES = host-bison host-flex
+GRUB2_DEPENDENCIES = host-bison host-flex host-grub2
+HOST_GRUB2_DEPENDENCIES = host-bison host-flex
+GRUB2_INSTALL_IMAGES = YES
+GRUB2_INSTALL_TARGET = NO
 
 GRUB2_BUILTIN_MODULES = $(call qstrip,$(BR2_TARGET_GRUB2_BUILTIN_MODULES))
 GRUB2_BUILTIN_CONFIG = $(call qstrip,$(BR2_TARGET_GRUB2_BUILTIN_CONFIG))

@@ -39,26 +42,24 @@ GRUB2_PLATFORM = efi
 endif
 
 # Grub2 is kind of special: it considers CC, LD and so on to be the
-# tools to build the native tools (i.e to be executed on the build
-# machine), and uses TARGET_CC, TARGET_CFLAGS, TARGET_CPPFLAGS,
-# TARGET_LDFLAGS to build the bootloader itself. However, to add to
-# the confusion, it also uses NM, OBJCOPY and STRIP to build the
-# bootloader itself; none of these are used to build the native
-# tools.
+# tools to build the host programs and uses TARGET_CC, TARGET_CFLAGS,
+# TARGET_CPPFLAGS, TARGET_LDFLAGS to build the bootloader itself.
 #
 # NOTE: TARGET_STRIP is overridden by !BR2_STRIP_strip, so always
 # use the cross compile variant to ensure grub2 builds
 
+HOST_GRUB2_CONF_ENV = \
+	CPP="$(HOSTCC) -E"
+
 GRUB2_CONF_ENV = \
-	$(HOST_CONFIGURE_OPTS) \
-	CPP="$(HOSTCC) -E" \
+	CPP="$(TARGET_CC) -E" \
 	TARGET_CC="$(TARGET_CC)" \
 	TARGET_CFLAGS="$(TARGET_CFLAGS)" \
 	TARGET_CPPFLAGS="$(TARGET_CPPFLAGS) -fno-stack-protector" \
 	TARGET_LDFLAGS="$(TARGET_LDFLAGS)" \
-	NM="$(TARGET_NM)" \
-	OBJCOPY="$(TARGET_OBJCOPY)" \
-	STRIP="$(TARGET_CROSS)strip"
+	TARGET_NM="$(TARGET_NM)" \
+	TARGET_OBJCOPY="$(TARGET_OBJCOPY)" \
+	TARGET_STRIP="$(TARGET_CROSS)strip"
 
 GRUB2_CONF_OPTS = \
 	--target=$(GRUB2_TARGET) \

@@ -72,12 +73,13 @@ GRUB2_CONF_OPTS = \
 	--enable-libzfs=no \
 	--disable-werror
 
-# We don't want all the native tools and Grub2 modules to be installed
-# in the target. So we in fact install everything into the host
-# directory, and the image generation process (below) will use the
-# grub-mkimage tool and Grub2 modules from the host directory.
-
-GRUB2_INSTALL_TARGET_OPTS = DESTDIR=$(HOST_DIR) install
+HOST_GRUB2_CONF_OPTS = \
+	--disable-grub-mkfont \
+	--enable-efiemu=no \
+	ac_cv_lib_lzma_lzma_code=no \
+	--enable-device-mapper=no \
+	--enable-libzfs=no \
+	--disable-werror
 
 ifeq ($(BR2_TARGET_GRUB2_I386_PC),y)
 define GRUB2_IMAGE_INSTALL_ELTORITO

@@ -86,10 +88,10 @@ define GRUB2_IMAGE_INSTALL_ELTORITO
 endef
 endif
 
-define GRUB2_IMAGE_INSTALLATION
+define GRUB2_INSTALL_IMAGES_CMDS
 	mkdir -p $(dir $(GRUB2_IMAGE))
-	$(HOST_DIR)/bin/grub-mkimage \
-		-d $(HOST_DIR)/lib/grub/$(GRUB2_TUPLE) \
+	$(HOST_DIR)/usr/bin/grub-mkimage \
+		-d $(@D)/grub-core/ \
 		-O $(GRUB2_TUPLE) \
 		-o $(GRUB2_IMAGE) \
 		-p "$(GRUB2_PREFIX)" \

@@ -99,14 +101,14 @@ define GRUB2_IMAGE_INSTALLATION
 	$(INSTALL) -D -m 0644 boot/grub2/grub.cfg $(GRUB2_CFG)
 	$(GRUB2_IMAGE_INSTALL_ELTORITO)
 endef
-GRUB2_POST_INSTALL_TARGET_HOOKS += GRUB2_IMAGE_INSTALLATION
 
 ifeq ($(GRUB2_PLATFORM),efi)
 define GRUB2_EFI_STARTUP_NSH
 	echo $(notdir $(GRUB2_IMAGE)) > \
 		$(BINARIES_DIR)/efi-part/startup.nsh
 endef
-GRUB2_POST_INSTALL_TARGET_HOOKS += GRUB2_EFI_STARTUP_NSH
+GRUB2_POST_INSTALL_IMAGES_HOOKS += GRUB2_EFI_STARTUP_NSH
 endif
 
 $(eval $(autotools-package))
+$(eval $(host-autotools-package))

index 9a61b3b633..f760f95e84 100644
@@ -76,6 +76,14 @@ config BR2_TARGET_GRUB2_BUILTIN_CONFIG
 	  device and other configuration parameters, but however menu
 	  entries cannot be described in this embedded configuration.
 
+config BR2_TARGET_GRUB2_INSTALL_TOOLS
+	bool "install grub2 tools"
+	help
+	  Install support tools to interact with GNU GRUB Multiboot boot
+	  loader.
+	  This will also install the Grub 2 loadable modules to the
+	  target.
+
 endif # BR2_TARGET_GRUB2
 
 comment "grub2 needs a toolchain w/ wchar"

index 1b366d0407..bb678ef5de 100644
@@ -12,7 +12,12 @@ GRUB2_LICENSE_FILES = COPYING
 GRUB2_DEPENDENCIES = host-bison host-flex host-grub2
 HOST_GRUB2_DEPENDENCIES = host-bison host-flex
 GRUB2_INSTALL_IMAGES = YES
+
+ifeq ($(BR2_TARGET_GRUB2_INSTALL_TOOLS),y)
+GRUB2_INSTALL_TARGET = YES
+else
 GRUB2_INSTALL_TARGET = NO
+endif
 
 GRUB2_BUILTIN_MODULES = $(call qstrip,$(BR2_TARGET_GRUB2_BUILTIN_MODULES))
 GRUB2_BUILTIN_CONFIG = $(call qstrip,$(BR2_TARGET_GRUB2_BUILTIN_CONFIG))

index 7f97696735..66b8d89932 100755
@@ -20,6 +20,10 @@ declare -a IGNORES=(
 	# pru-software-support) legitimately install ELF binaries that
 	# are not for the target architecture
 	"/usr/share"
+
+	# Skip files in /lib/grub, since it is possible to have it
+	# for a different architecture (e.g. i386 grub on x86_64).
+	"/lib/grub"
 )
 
 while getopts p:l:r:a:i: OPT ; do

index f760f95e84..5e0e47a5bb 100644
@@ -2,10 +2,13 @@ config BR2_TARGET_GRUB2_ARCH_SUPPORTS
 	bool
 	default y if BR2_i386
 	default y if BR2_x86_64
+	default y if BR2_arm
+	default y if BR2_aarch64
 
 config BR2_TARGET_GRUB2
 	bool "grub2"
 	depends on BR2_TARGET_GRUB2_ARCH_SUPPORTS
+	depends on BR2_USE_MMU
 	depends on BR2_USE_WCHAR
 	help
 	  GNU GRUB is a Multiboot boot loader. It was derived from

@@ -29,12 +32,14 @@ choice
 
 config BR2_TARGET_GRUB2_I386_PC
 	bool "i386-pc"
+	depends on BR2_i386 || BR2_x86_64
 	help
 	  Select this option if the platform you're targetting is a
 	  x86 or x86-64 legacy BIOS based platform.
 
 config BR2_TARGET_GRUB2_I386_EFI
 	bool "i386-efi"
+	depends on BR2_i386 || BR2_x86_64
 	help
 	  Select this option if the platform you're targetting has a
 	  32 bits EFI BIOS. Note that some x86-64 platforms use a 32

@@ -42,14 +47,38 @@ config BR2_TARGET_GRUB2_I386_EFI
 
 config BR2_TARGET_GRUB2_X86_64_EFI
 	bool "x86-64-efi"
-	depends on BR2_ARCH_IS_64
+	depends on BR2_x86_64
 	help
 	  Select this option if the platform you're targetting has a
 	  64 bits EFI BIOS.
 
+config BR2_TARGET_GRUB2_ARM_UBOOT
+	bool "arm-uboot"
+	depends on BR2_arm
+	help
+	  Select this option if the platform you're targetting is an
+	  ARM u-boot platform, and you want to boot Grub 2 as an u-boot
+	  compatible image.
+
+config BR2_TARGET_GRUB2_ARM_EFI
+	bool "arm-efi"
+	depends on BR2_arm
+	help
+	  Select this option if the platform you're targetting is an
+	  ARM platform and you want to boot Grub 2 as an EFI
+	  application.
+
+config BR2_TARGET_GRUB2_ARM64_EFI
+	bool "arm64-efi"
+	depends on BR2_aarch64
+	help
+	  Select this option if the platform you're targetting is an
+	  Aarch64 platform and you want to boot Grub 2 as an EFI
+	  application.
+
 endchoice
 
-if BR2_TARGET_GRUB2_I386_PC
+if BR2_TARGET_GRUB2_I386_PC || BR2_TARGET_GRUB2_ARM_UBOOT
 
 config BR2_TARGET_GRUB2_BOOT_PARTITION
 	string "boot partition"

@@ -60,13 +89,17 @@ config BR2_TARGET_GRUB2_BOOT_PARTITION
 	  first disk if using a legacy partition table, or 'hd0,gpt1'
 	  if using GPT partition table.
 
-endif # BR2_TARGET_GRUB2_I386_PC
+endif # BR2_TARGET_GRUB2_I386_PC || BR2_TARGET_GRUB2_ARM_UBOOT
 
 config BR2_TARGET_GRUB2_BUILTIN_MODULES
 	string "builtin modules"
 	default "boot linux ext2 fat squash4 part_msdos part_gpt normal biosdisk" if BR2_TARGET_GRUB2_I386_PC
 	default "boot linux ext2 fat squash4 part_msdos part_gpt normal efi_gop" \
-		if BR2_TARGET_GRUB2_I386_EFI || BR2_TARGET_GRUB2_X86_64_EFI
+		if BR2_TARGET_GRUB2_I386_EFI || \
+		BR2_TARGET_GRUB2_X86_64_EFI || \
+		BR2_TARGET_GRUB2_ARM_EFI || \\
+		BR2_TARGET_GRUB2_ARM64_EFI
+	default "linux ext2 fat part_msdos normal" if BR2_TARGET_GRUB2_ARM_UBOOT
 
 config BR2_TARGET_GRUB2_BUILTIN_CONFIG
 	string "builtin config"

@@ -88,4 +121,5 @@ endif # BR2_TARGET_GRUB2
 
 comment "grub2 needs a toolchain w/ wchar"
 	depends on BR2_TARGET_GRUB2_ARCH_SUPPORTS
+	depends on BR2_USE_MMU
 	depends on !BR2_USE_WCHAR

index bb678ef5de..65371f0170 100644
@@ -44,6 +44,27 @@ GRUB2_PREFIX = /EFI/BOOT
 GRUB2_TUPLE = x86_64-efi
 GRUB2_TARGET = x86_64
 GRUB2_PLATFORM = efi
+else ifeq ($(BR2_TARGET_GRUB2_ARM_UBOOT),y)
+GRUB2_IMAGE = $(BINARIES_DIR)/boot-part/grub/grub.img
+GRUB2_CFG = $(BINARIES_DIR)/boot-part/grub/grub.cfg
+GRUB2_PREFIX = ($(GRUB2_BOOT_PARTITION))/boot/grub
+GRUB2_TUPLE = arm-uboot
+GRUB2_TARGET = arm
+GRUB2_PLATFORM = uboot
+else ifeq ($(BR2_TARGET_GRUB2_ARM_EFI),y)
+GRUB2_IMAGE = $(BINARIES_DIR)/efi-part/EFI/BOOT/bootarm.efi
+GRUB2_CFG = $(BINARIES_DIR)/efi-part/EFI/BOOT/grub.cfg
+GRUB2_PREFIX = /EFI/BOOT
+GRUB2_TUPLE = arm-efi
+GRUB2_TARGET = arm
+GRUB2_PLATFORM = efi
+else ifeq ($(BR2_TARGET_GRUB2_ARM64_EFI),y)
+GRUB2_IMAGE = $(BINARIES_DIR)/efi-part/EFI/BOOT/bootaa64.efi
+GRUB2_CFG = $(BINARIES_DIR)/efi-part/EFI/BOOT/grub.cfg
+GRUB2_PREFIX = /EFI/BOOT
+GRUB2_TUPLE = arm64-efi
+GRUB2_TARGET = aarch64
+GRUB2_PLATFORM = efi
 endif
 
 # Grub2 is kind of special: it considers CC, LD and so on to be the

new file mode 100644
index 0000000000..f93ab9d64f
@@ -0,0 +1,30 @@
+image efi-part.vfat {
+  vfat {
+    file startup.nsh {
+      image = "efi-part/startup.nsh"
+    }
+    file EFI {
+      image = "efi-part/EFI"
+    }
+    file Image {
+      image = "Image"
+    }
+  }
+  size = 32M
+}
+
+image disk.img {
+
+  hdimage {
+  }
+
+  partition boot {
+    partition-type = 0xEF
+    image = "efi-part.vfat"
+  }
+
+  partition root {
+    partition-type = 0x83
+    image = "rootfs.ext2"
+  }
+}

new file mode 100644
index 0000000000..ab88da91b9
@@ -0,0 +1,6 @@
+set default="0"
+set timeout="5"
+
+menuentry "Buildroot" {
+	linux /Image root=/dev/vda2 rootwait console=ttyAMA0
+}

new file mode 100755
index 0000000000..f0214dc866
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+BOARD_DIR="$(dirname $0)"
+
+cp -f ${BOARD_DIR}/grub.cfg ${BINARIES_DIR}/efi-part/EFI/BOOT/grub.cfg

new file mode 100644
index 0000000000..e62278f6d2
@@ -0,0 +1,17 @@
+Run the emulation with:
+
+qemu-system-aarch64 \
+	-M virt \
+	-cpu cortex-a57 \
+	-m 512 \
+	-nographic \
+	-bios </path/to/QEMU_EFI.fd> \
+	-drive file=output/images/disk.img,if=none,format=raw,id=hd0 \
+	-device virtio-blk-device,drive=hd0 \
+	-netdev user,id=eth0 \
+	-device virtio-net-device,netdev=eth0
+
+Note that </path/to/QEMU_EFI.fd> needs to point to a valid aarch64 UEFI
+firmware image for qemu.
+It may be provided by your distribution as a edk2-aarch64 or AAVMF
+package, in path such as /usr/share/edk2/aarch64/QEMU_EFI.fd .

new file mode 100644
index 0000000000..e4e20b09ba
@@ -0,0 +1,33 @@
+# Architecture
+BR2_aarch64=y
+
+# Toolchain, required for eudev and grub
+BR2_TOOLCHAIN_BUILDROOT_WCHAR=y
+
+# System
+BR2_TARGET_GENERIC_GETTY_PORT="ttyAMA0"
+BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_EUDEV=y
+
+## Required tools to create bootable media
+BR2_PACKAGE_HOST_GENIMAGE=y
+
+# Bootloader
+BR2_TARGET_GRUB2=y
+BR2_TARGET_GRUB2_AARCH64_EFI=y
+
+# Filesystem / image
+BR2_TARGET_ROOTFS_EXT2=y
+BR2_TARGET_ROOTFS_EXT2_4=y
+BR2_TARGET_ROOTFS_EXT2_SIZE="200M"
+# BR2_TARGET_ROOTFS_TAR is not set
+BR2_ROOTFS_POST_IMAGE_SCRIPT="board/aarch64-efi/post-image.sh support/scripts/genimage.sh"
+BR2_ROOTFS_POST_SCRIPT_ARGS="-c board/aarch64-efi/genimage-efi.cfg"
+
+# Linux headers same as kernel, a 4.18 series
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_18=y
+
+# Kernel
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_CUSTOM_VERSION=y
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.18.10"
+BR2_LINUX_KERNEL_USE_ARCH_DEFAULT_CONFIG=y

index f6fd4566fe..9d8448f866 100644
@@ -53,8 +53,8 @@ To test your BIOS image in Qemu
 
 qemu-system-{i386,x86-64} -hda disk.img
 
-Notes on using Grub2 for EFI-based platforms
-============================================
+Notes on using Grub2 for x86/x86_64 EFI-based platforms
+=======================================================
 
 1. Create a disk image
    dd if=/dev/zero of=disk.img bs=1M count=32

@@ -83,16 +83,148 @@ Notes on using Grub2 for EFI-based platforms
    sudo losetup -d /dev/loop0
 7. Your disk.img is ready!
 
-To test your EFI image in Qemu
+To test your i386/x86-64 EFI image in Qemu
 ------------------------------
 
 1. Download the EFI BIOS for Qemu
    Version IA32 or X64 depending on the chosen Grub2
    platform (i386-efi vs. x86-64-efi)
-   http://sourceforge.net/projects/edk2/files/OVMF/
+   https://www.kraxel.org/repos/jenkins/edk2/
+   (or use one provided by your distribution as OVMF)
 2. Extract, and rename OVMF.fd to bios.bin and
    CirrusLogic5446.rom to vgabios-cirrus.bin.
 3. qemu-system-{i386,x86-64} -L ovmf-dir/ -hda disk.img
 4. Make sure to pass pci=nocrs to the kernel command line,
    to workaround a bug in the EFI BIOS regarding the
    EFI framebuffer.
+
+Notes on using Grub2 for ARM u-boot-based platforms
+===================================================
+
+The following steps are used to exemplify the arm-uboot platform working in the
+simplest way possible and with a single buildroot-generated filesystem. The
+steps can of course be adapted to have a more common setup (i.e. with a
+separate boot partition).
+
+ 1. Load qemu_arm_vexpress_defconfig
+ 2. Enable u-boot with the vexpress_ca9x4 board name and with u-boot.elf image
+    format.
+ 3. Enable grub2 for the arm-uboot platform.
+ 4. Enable "Install kernel image to /boot in target" in the kernel menu to
+    populate a /boot directory with zImage in it.
+ 5. The upstream u-boot vexpress_ca9x4 doesn't have CONFIG_API enabled by
+    default, which is required.
+    Before building, patch u-boot (for example, make u-boot-extract to edit the
+    source before buildling) file include/configs/vexpress_common.h to define:
+
+    #define CONFIG_API
+    #define CONFIG_SYS_MMC_MAX_DEVICE   1
+
+ 6. Create a custom grub2 menu entries config file with the following contents
+    and set its path in BR2_TARGET_GRUB2_CFG:
+
+    set default="0"
+    set timeout="5"
+
+    menuentry "Buildroot" {
+        set root='(hd0)'
+        linux /boot/zImage root=/dev/mmcblk0 console=ttyAMA0
+        devicetree /boot/vexpress-v2p-ca9.dtb
+    }
+
+ 7. Create a custom builtin config file with the following contents and set its
+    path in BR2_TARGET_GRUB2_BUILTIN_CONFIG:
+
+    set root=(hd0)
+    set prefix=/boot/grub
+
+ 8. Create a custom post-build script which copies files from
+    ${BINARIES_DIR}/boot-part to $(TARGET_DIR)/boot (set its path in
+    BR2_ROOTFS_POST_BUILD_SCRIPT):
+
+    #!/bin/sh
+    cp -r ${BINARIES_DIR}/boot-part/* ${TARGET_DIR}/boot/
+
+ 9. make
+10. Run qemu with:
+
+    qemu-system-arm -M vexpress-a9 -kernel output/images/u-boot -m 1024 \
+    -nographic -sd output/images/rootfs.ext2
+
+11. In u-boot, stop at the prompt and run grub2 with:
+
+  => ext2load mmc 0:0 ${loadaddr} /boot/grub/grub.img
+  => bootm
+
+12. This should bring the grub2 menu, upon which selecting the "Buildroot"
+    entry should boot Linux.
+
+
+Notes on using Grub2 for Aarch64 EFI-based platforms
+====================================================
+
+The following steps are used to exemplify the arm64-efi platform with the use
+of qemu and EFI firmware built for qemu.
+
+ 1. Load qemu_aarch64_virt_defconfig
+ 2. Enable grub2 for the arm64-efi platform.
+ 3. Create a custom grub2 menu entries config file with the following contents
+    and set its path in BR2_TARGET_GRUB2_CFG:
+
+    set default="0"
+    set timeout="5"
+    menuentry "Buildroot" {
+        linux /Image console=ttyAMA0
+    }
+
+ 4. Enable host genimage and create a genimage.cfg script which creates the
+    disk image containing a EFI system partition:
+
+    image efi-part.vfat {
+      vfat {
+        file startup.nsh {
+          image = "efi-part/startup.nsh"
+        }
+        file EFI {
+          image = "efi-part/EFI"
+        }
+        file Image {
+          image = "Image"
+        }
+      }
+      size = 16M
+    }
+    image disk.img {
+      hdimage {
+      }
+      partition boot {
+        partition-type = 0xEF
+        image = "efi-part.vfat"
+      }
+    }
+
+ 5. Create a custom post-image script  (set its path in BR2_ROOTFS_POST_IMAGE_SCRIPT):
+
+    BOARD_DIR="$(dirname $0)"
+    GENIMAGE_CFG="${BOARD_DIR}/genimage.cfg"
+    GENIMAGE_TMP="${BUILD_DIR}/genimage.tmp"
+    rm -rf "${GENIMAGE_TMP}"
+    genimage                              \
+           --rootpath "${TARGET_DIR}"     \
+           --tmppath "${GENIMAGE_TMP}"    \
+           --inputpath "${BINARIES_DIR}"  \
+           --outputpath "${BINARIES_DIR}" \
+           --config "${GENIMAGE_CFG}"
+
+ 6. Download the EFI firmware for qemu aarch64
+    https://www.kraxel.org/repos/jenkins/edk2/
+    (or use one provided by your distribution as OVMF-aarch64 or AAVMF)
+
+ 7. Run qemu with:
+
+    qemu-system-aarch64 -M virt -cpu cortex-a57 -m 512 -nographic \
+    -bios <path/to/EDK2>/QEMU_EFI.fd -hda output/images/disk.img \
+    -netdev user,id=eth0 -device virtio-net-device,netdev=eth0
+
+ 8. This should bring the grub2 menu, upon which selecting the "Buildroot"
+    entry should boot Linux.