grub: add hooks, fix GRUB font & wallpaper, introduce grub-with-dtb extension

- introduce hooks `grub_early_config`, `grub_pre_install` and `grub_late_config`
  - what we see here is an extension that itself has hooks, that just works
- introduce extension `grub-with-dtb`, which
  - enables `grub` extension
  - requires `BOOT_FDT_FILE` to be set
  - includes `/etc/armbian-grub-with-dtb` with `BOOT_FDT_FILE=` in the bsp-cli
  - includes `/etc/kernel/postinst.d/armbian-grub-with-dtb` in the bsp-cli
     - which reads the above and creates links for `/boot/armbian-dtb-<version>` when deploying deb's
  - adds implementations of the hooks above to
    - replace the distro's `10_linux` with our own `09_linux_with_dtb`
      - which looks for `/boot/armbian-dtb-<version>`
    - forcibly run  `/etc/kernel/postinst.d/armbian-grub-with-dtb` during image build, since bsp-cli is installed after linux-image
- uefi-arm64: enable GRUB wallpaper by setting `UEFI_GRUB_TERMINAL=gfxterm`
- force GRUB_FONT so Ubuntu is not confused and gfxterm (incl wallpaper) finally works

extensions/grub-with-dtb.sh

@@ -0,0 +1,95 @@
+#
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2023 Ricardo Pardini <ricardo@pardini.net>
+# This file is a part of the Armbian Build Framework https://github.com/armbian/build/
+#
+
+# `grub-with-dtb` is a superset of `grub`, but hacked to boot using DeviceTree.
+# this is useful for EFI-only-on-ARM64 such as the ThinkPad x13s, Phytium D2000, and possibly others.
+# The way the kernel behaves being handled _both_ an ACPI table and a DeviceTree is controlled (at least) by:
+# - "efi=noruntime" (get info from EFI/ACPI, but don't use its Runtime Services, and fall back to OF/DT when missing)
+# - "acpi=off"  (don't use ACPI at all, and fall back to OF/DT completely: useful for SBCs)
+# use GRUB_CMDLINE_LINUX_DEFAULT to set these options in the board file.
+
+enable_extension "grub"
+
+# Ensure config is sufficient for operation
+function extension_prepare_config__prepare_grub_with_dtb() {
+	# Make sure BOOT_FDT_FILE is set and not empty
+	[[ -n "${BOOT_FDT_FILE}" ]] || exit_with_error "BOOT_FDT_FILE is not set, required for grub-with-dtb"
+
+	display_alert "initializing config" "${EXTENSION} :: ${BOARD}" "info"
+}
+
+# Hack the bsp-cli to:
+# - write the BOOT_FDT_FILE information to a configuration file. (/etc/armbian-grub-with-dtb)
+# - add a kernel install/upgrade hook to automatically deploy the DTB file to the boot partition, in a way that
+#   works across Debian and Ubuntu. it reads /etc/armbian-grub-with-dtb and puts symlinks or copies in /boot/dtb-<kernel-version>
+function post_family_tweaks_bsp__add_grub_with_dtb_config_file() {
+	: "${destination:?}"
+	display_alert "adding grub-with-dtb config file" "${EXTENSION} :: ${BOARD}" "info"
+	# maybe add this to conffiles?
+	cat <<- EOD > "${destination}"/etc/armbian-grub-with-dtb
+		BOOT_FDT_FILE="${BOOT_FDT_FILE}"
+	EOD
+}
+
+function post_family_tweaks_bsp__add_grub_with_dtb_kernel_hook() {
+	: "${destination:?}"
+	display_alert "adding grub-with-dtb kernel hook" "${EXTENSION} :: ${BOARD}" "info"
+	run_host_command_logged mkdir -p "${destination}"/etc/kernel/postinst.d
+	cat <<- 'EOD' > "${destination}"/etc/kernel/postinst.d/armbian-grub-with-dtb
+		#! /bin/bash
+		set -e
+
+		declare kversion="$1" # # We're passed the version of the kernel being installed
+		echo "Armbian: installing DTB for GRUB: $kversion" >&2
+
+		if [[ -f /etc/armbian-grub-with-dtb ]]; then
+			echo "Armbian: /etc/armbian-grub-with-dtb found, installing DTB for GRUB" >&2
+			declare BOOT_FDT_FILE
+			source /etc/armbian-grub-with-dtb
+			declare target_dtb_file="/boot/armbian-dtb-${kversion}"
+			declare source_dtb_file="/usr/lib/linux-image-${kversion}/${BOOT_FDT_FILE}"
+			echo "Armbian: installing DTB for GRUB: $source_dtb_file -> $target_dtb_file" >&2
+			cp -v "${source_dtb_file}" "${target_dtb_file}"
+			echo "Armbian: installing DTB for GRUB: done." >&2
+		else
+			echo "Armbian: /etc/armbian-grub-with-dtb not found, skipping DTB for GRUB" >&2
+		fi
+	EOD
+	run_host_command_logged chmod -v +x "${destination}"/etc/kernel/postinst.d/armbian-grub-with-dtb
+}
+
+# `grub_early_config` and `grub_late_config` and `grub_pre_install` are hooks exposed by the `grub` extension
+
+function grub_early_config__deploy_dtb_for_grub() {
+	# @TODO: this could be deployed in the bsp-cli for consistency/updates?
+	# Get rid of the original grub-mkconfig scripts and add our own.
+	run_host_command_logged rm -fv "${MOUNT}"/etc/grub.d/{10_linux,20_linux_xen} # or maybe just remove their executable bit?
+	run_host_command_logged cp -v "${SRC}/packages/blobs/grub/09_linux_with_dtb.sh" "${MOUNT}"/etc/grub.d/09_linux_with_dtb.sh
+	run_host_command_logged chmod -v +x "${MOUNT}"/etc/grub.d/09_linux_with_dtb.sh
+}
+
+function grub_pre_install__force_run_kernel_hook_for_armbian_dtb() {
+	# Run the kernel hook to deploy the DTB file to the boot partition.
+	# This is done forcibly here during `grub_pre_install`, since the kernel hook is deployed in the bsp-cli package
+	# which is only deployed after the linux-image package is installed and thus is not run.
+	display_alert "deploy DTB for GRUB for image build" "${EXTENSION} :: ${BOARD}" "info"
+	chroot_custom "${MOUNT}" 'for k in $(linux-version list); do /etc/kernel/postinst.d/armbian-grub-with-dtb "$k"; done'
+}
+
+function grub_late_config__check_dtb_in_grub_cfg() {
+	if [[ "${SHOW_DEBUG}" == "yes" ]]; then
+		display_alert "Debugging" "GRUB config and /boot contents" "info"
+		run_tool_batcat "${MOUNT}/boot/grub/grub.cfg"
+		run_host_command_logged ls -la --color=always "${MOUNT}"/boot
+	fi
+
+	if ! grep -q 'devicetree' "${MOUNT}/boot/grub/grub.cfg"; then
+		display_alert "Sanity check failed" "GRUB DTB not found in grub.cfg; RELEASE=${RELEASE}" "warn"
+	else
+		display_alert "Sanity check passed" "GRUB DTB found in grub.cfg; RELEASE=${RELEASE}" "info"
+	fi
+	return 0
+}