From 5fa8ca30ef23bda079e6512ebdae86899785b301 Mon Sep 17 00:00:00 2001
From: cyteen <cyteen@ring-zero.co.uk>
Date: Wed, 4 Mar 2026 15:10:49 +0000
Subject: [PATCH] Install script to allow starting zfs boot manager from grub
 menu.

---
 020_grub_zbm_chainload.sh | 88 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 020_grub_zbm_chainload.sh

diff --git a/020_grub_zbm_chainload.sh b/020_grub_zbm_chainload.sh
new file mode 100644
index 0000000..ecdacac
--- /dev/null
+++ b/020_grub_zbm_chainload.sh
@@ -0,0 +1,88 @@
+#!/usr/bin/env bash
+set -x
+
+# Dependencies
+sudo apt update && sudo apt install -y binutils wget binwalk # lastversion
+
+# --- CONFIGURATION ---
+REPO="zbm-dev/zfsbootmenu"
+ZBM_VERSION=$(lastversion --format tag "${REPO}")
+ZBM_RELEASE="recovery"
+KERNEL=$(uname -r | cut -d'.' -f1,2)
+ARCH=$(uname -m)
+
+# Target directory for GRUB to find
+FINAL_DEST=/boot/zfsbootmenu
+sudo mkdir -p ${FINAL_DEST}
+
+ZBM_EFI="zfsbootmenu-${ZBM_RELEASE}-${ARCH}-${ZBM_VERSION}-linux${KERNEL}.EFI"
+ZBM_URL="https://github.com/zbm-dev/zfsbootmenu/releases/download/${ZBM_VERSION}/${ZBM_EFI}"
+
+# --- TMPFS SETUP ---
+WORK_DIR=$(mktemp -d -p /dev/shm zbm_extract.XXXXXX)
+cleanup() {
+  echo "--- Cleaning up RAM storage ---"
+  rm -rf "$WORK_DIR"
+  rm -f "$ZBM_EFI"
+}
+trap cleanup EXIT
+
+echo "Downloading ZFSBootMenu ${ZBM_VERSION}..."
+# lastversion -d \
+#   --output "${ZBM_EFI}" \
+#   zbm-dev/zfsbootmenu \
+#   --filter "${ZBM_RELEASE}.*${ARCH}.*${ZBM_VERSION}.*${KERNEL}.*EFI"
+
+sudo curl -L "${ZBM_URL}" -o "${ZBM_EFI}"
+
+# Extraction paths
+KERNEL_OUT="${WORK_DIR}/vmlinuz-zbm"
+INITRD_OUT="${WORK_DIR}/initrd-zbm.img"
+
+echo "--- Extracting assets from $ZBM_EFI ---"
+
+# 1. Extract Kernel & Initrd
+if objcopy --dump-section .linux="$KERNEL_OUT" "$ZBM_EFI" 2>/dev/null &&
+  objcopy --dump-section .initrd="$INITRD_OUT" "$ZBM_EFI" 2>/dev/null; then
+
+  echo "[✓] Extraction successful. Moving to $FINAL_DEST..."
+  sudo cp "$KERNEL_OUT" "$FINAL_DEST/"
+  sudo cp "$INITRD_OUT" "$FINAL_DEST/"
+else
+  echo "[!] Extraction failed. Check if binutils is installed correctly."
+  exit 1
+fi
+
+# --- GRUB MENU GENERATION ---
+conf_print_zbm_grub_menu() {
+  cat <<EOF
+#!/bin/sh
+exec tail -n +3 \$0
+# This file provides an easy way to add custom menu entries.
+menuentry "ZFSBootMenu (Extracted)" --class zfs --class gnu-linux {
+    insmod part_gpt
+    insmod zfs
+    insmod gzio
+
+    # Use UUID instead of file search
+    search --no-floppy --fs-uuid --set=root f383eb9e238f6712
+
+    echo "Loading ZFSBootMenu Kernel..."
+    linux /zfsbootmenu/vmlinuz-zbm zbm.import_policy=hostid zbm.prefer=rpool loglevel=4
+
+    echo "Loading ZFSBootMenu Initrd..."
+    initrd /zfsbootmenu/initrd-zbm.img
+}
+EOF
+}
+
+echo "Generating GRUB configuration..."
+conf_print_zbm_grub_menu | sudo tee /etc/grub.d/40_zbm
+sudo chmod +x /etc/grub.d/40_zbm
+
+echo "Updating GRUB..."
+sudo update-grub
+
+echo "---------------------------------------"
+echo "Done! Files are located in $FINAL_DEST"
+grep -A 10 "menuentry \"ZFSBootMenu" /boot/grub/grub.cfg