Add GRUB EFI build recipe and chainload configuration

Builds GRUB 2.12 for the host machine (not Redox target) using template=custom.
Produces a 540 KiB standalone PE32+ EFI binary with GPT, FAT, ext2,
chainloader, and utility modules. The grub.cfg chainloads the Redox
bootloader from EFI/REDBEAR/redbear.efi.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

local/recipes/core/grub/grub.cfg

@@ -0,0 +1,28 @@
+# Red Bear OS GRUB Configuration
+#
+# GRUB presents this menu at boot and chainloads the Redox bootloader.
+# The Redox bootloader then reads the RedoxFS partition and boots the kernel.
+#
+# Place this file at EFI/BOOT/grub.cfg on the ESP.
+# The install-grub.sh script handles this automatically.
+#
+# To customize: edit this file before running install-grub.sh,
+# or modify the ESP directly with mtools:
+#   mcopy -i harddrive.img@@1048576 grub.cfg ::EFI/BOOT/grub.cfg
+
+set default=0
+set timeout=5
+
+# Default: boot Red Bear OS via Redox bootloader chainload
+menuentry "Red Bear OS" {
+    chainloader /EFI/REDBEAR/redbear.efi
+    boot
+}
+
+menuentry "Reboot" {
+    reboot
+}
+
+menuentry "Shutdown" {
+    halt
+}

local/recipes/core/grub/recipe.toml

@@ -0,0 +1,126 @@
+# Red Bear OS — GRUB Boot Manager
+#
+# Builds GRUB for the HOST machine (not the Redox target).
+# GRUB is a build tool that produces standalone EFI binaries.
+# The resulting grub.efi chainloads the Redox bootloader.
+#
+# Output: /usr/lib/boot/grub.efi, /usr/lib/boot/grub.cfg
+#
+# Build: make r.grub
+# Install into image: ./local/scripts/install-grub.sh build/x86_64/harddrive.img
+#
+# Requires: gcc, make, bison, flex, autoconf, automake on host
+
+[source]
+tar = "https://ftp.gnu.org/gnu/grub/grub-2.12.tar.xz"
+
+[build]
+template = "custom"
+script = """
+# GRUB must be built for the HOST machine, not the Redox target.
+# It is a build tool that produces EFI binaries for bare-metal boot.
+# Override cookbook cross-compilation environment.
+
+# Force HOST compiler — cookbook sets CC to Redox cross-compiler.
+# GRUB is a host build tool, not a Redox binary.
+unset CC CXX CPP LD AR NM RANLIB OBJCOPY STRIP PKG_CONFIG
+unset CFLAGS CXXFLAGS CPPFLAGS LDFLAGS
+
+# Out-of-tree build (GRUB requires this for some configurations)
+mkdir -p "${COOKBOOK_BUILD}/grub-build"
+cd "${COOKBOOK_BUILD}/grub-build"
+
+# GRUB release tarballs miss extra_deps.lst (normally generated by autogen.sh)
+touch "${COOKBOOK_SOURCE}/grub-core/extra_deps.lst"
+
+# Configure for host, targeting x86_64 EFI platform output.
+# --target=x86_64 means "produce boot images for x86_64"
+# --with-platform=efi means "EFI platform output"
+# We intentionally do NOT set --host (it should be the build machine).
+echo "Configuring GRUB for x86_64 EFI..."
+"${COOKBOOK_SOURCE}/configure" \
+    --target=x86_64 \
+    --with-platform=efi \
+    --disable-werror \
+    --disable-nls \
+    --disable-grub-mkfont \
+    --disable-grub-themes \
+    --disable-grub-mount \
+    --disable-device-mapper \
+    --disable-libzfs \
+    --prefix="${COOKBOOK_STAGE}/usr"
+
+echo "Building GRUB..."
+make -j "${COOKBOOK_MAKE_JOBS}"
+
+# Create output directory
+mkdir -p "${COOKBOOK_STAGE}/usr/lib/boot"
+
+# Locate GRUB modules directory.
+# In an out-of-tree build, modules are in grub-core/ under the build dir.
+MOD_DIR=""
+for d in grub-core .; do
+    if [ -f "${d}/part_gpt.mod" ]; then
+        MOD_DIR="${d}"
+        break
+    fi
+done
+
+if [ -z "${MOD_DIR}" ]; then
+    echo "ERROR: Cannot find GRUB modules directory" >&2
+    echo "Looked in: grub-core/ ." >&2
+    find . -name "part_gpt.mod" 2>/dev/null || true
+    exit 1
+fi
+
+echo "Found GRUB modules in: ${MOD_DIR}"
+
+# Build standalone EFI image with curated module set.
+# -O x86_64-efi: output format
+# -d MOD_DIR: module search directory
+# -p /EFI/BOOT: prefix for GRUB config search path
+# The resulting image is self-contained (no external module files needed).
+echo "Creating standalone GRUB EFI image..."
+./grub-mkimage \
+    -O x86_64-efi \
+    -d "${MOD_DIR}" \
+    -o "${COOKBOOK_STAGE}/usr/lib/boot/grub.efi" \
+    -p /EFI/BOOT \
+    part_gpt \
+    part_msdos \
+    fat \
+    ext2 \
+    normal \
+    configfile \
+    search \
+    search_fs_uuid \
+    search_label \
+    chain \
+    echo \
+    test \
+    ls \
+    cat \
+    halt \
+    reboot
+
+# Verify output
+if [ ! -f "${COOKBOOK_STAGE}/usr/lib/boot/grub.efi" ]; then
+    echo "ERROR: grub.efi was not created" >&2
+    exit 1
+fi
+
+GRUB_SIZE=$(stat -f%z "${COOKBOOK_STAGE}/usr/lib/boot/grub.efi" 2>/dev/null || stat -c%s "${COOKBOOK_STAGE}/usr/lib/boot/grub.efi" 2>/dev/null || echo "unknown")
+echo "GRUB EFI image size: ${GRUB_SIZE} bytes"
+
+# Copy default GRUB configuration from recipe directory.
+# grub.cfg lives alongside recipe.toml, not in the extracted source tarball.
+if [ -f "${COOKBOOK_RECIPE}/grub.cfg" ]; then
+    cp "${COOKBOOK_RECIPE}/grub.cfg" "${COOKBOOK_STAGE}/usr/lib/boot/grub.cfg"
+    echo "Installed grub.cfg"
+else
+    echo "WARNING: grub.cfg not found in ${COOKBOOK_RECIPE}" >&2
+fi
+
+echo "GRUB recipe complete."
+echo "Install with: ./local/scripts/install-grub.sh build/x86_64/harddrive.img"
+"""

recipes/core/grub

@@ -0,0 +1 @@
+../../local/recipes/core/grub

recipes/wip/services/grub/recipe.toml

@@ -1,5 +0,0 @@
-#TODO compilation error
-[source]
-tar = "https://ftp.gnu.org/gnu/grub/grub-2.12.tar.xz"
-[build]
-template = "configure"

recipes/wip/services/grub/recipe.toml

@@ -0,0 +1 @@
+../../../../local/recipes/core/grub/recipe.toml