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-rw-r--r--CHANGELOG.rst3
-rw-r--r--README.rst1
-rwxr-xr-xarchiso/mkarchiso127
-rw-r--r--configs/baseline/grub/grub.cfg29
-rw-r--r--configs/baseline/profiledef.sh4
-rw-r--r--configs/releng/efiboot/loader/entries/01-archiso-x86_64-linux.conf13
-rw-r--r--configs/releng/efiboot/loader/entries/02-archiso-x86_64-speech-linux.conf13
-rw-r--r--configs/releng/efiboot/loader/entries/03-archiso-x86_64-ram-linux.conf13
-rw-r--r--configs/releng/efiboot/loader/entries/04-archiso-x86_64-ram-speech-linux.conf7
-rw-r--r--configs/releng/efiboot/loader/loader.conf1
-rw-r--r--configs/releng/grub/grub.cfg46
-rw-r--r--configs/releng/packages.x86_642
-rw-r--r--docs/README.profile.rst13
13 files changed, 242 insertions, 30 deletions
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 90243e6..639c266 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -8,6 +8,9 @@ Changelog
Added
-----
+- Add ``uefi-ia32.grub.esp`` boot mode to support IA32 UEFI boot on x86_64 machines.
+- Add GRUB configuration files to profiles.
+
Changed
-------
diff --git a/README.rst b/README.rst
index 62cea01..6ac7434 100644
--- a/README.rst
+++ b/README.rst
@@ -17,6 +17,7 @@ The following packages need to be installed to be able to create an image with t
* e2fsprogs
* erofs-utils (optional)
* findutils
+* grub
* gzip
* libarchive
* libisoburn
diff --git a/archiso/mkarchiso b/archiso/mkarchiso
index e7f52b3..b81b700 100755
--- a/archiso/mkarchiso
+++ b/archiso/mkarchiso
@@ -41,6 +41,7 @@ airootfs_image_tool_options=()
cert_list=()
sign_netboot_artifacts=""
declare -A file_permissions=()
+efiboot_files=()
# adapted from GRUB_EARLY_INITRD_LINUX_STOCK in https://git.savannah.gnu.org/cgit/grub.git/tree/util/grub-mkconfig.in
readonly ucodes=('intel-uc.img' 'intel-ucode.img' 'amd-uc.img' 'amd-ucode.img' 'early_ucode.cpio' 'microcode.cpio')
@@ -518,6 +519,84 @@ _make_efibootimg() {
mmd -i "${work_dir}/efiboot.img" ::/EFI ::/EFI/BOOT
}
+_make_bootmode_uefi-ia32.grub.esp() {
+ # Fill Grub configuration files
+ sed "s|%ARCHISO_LABEL%|${iso_label}|g;
+ s|%INSTALL_DIR%|${install_dir}|g;
+ s|%ARCH%|${arch}|g" \
+ "${profile}/grub/grub.cfg" > "${work_dir}/grub.cfg"
+
+ # shellcheck disable=SC2016
+ printf 'configfile ${cmdpath}/grub.cfg\n' > "${work_dir}/grub-embed.cfg"
+
+ # Create EFI file
+ grub-mkstandalone -O i386-efi \
+ --modules="part_gpt part_msdos fat iso9660" \
+ --locales="en@quot" \
+ --themes="" \
+ -o "${work_dir}/BOOTIA32.EFI" "boot/grub/grub.cfg=${work_dir}/grub-embed.cfg"
+ # Add GRUB to the list of files used to calculate the required FAT image size.
+ efiboot_files+=("${work_dir}/BOOTIA32.EFI"
+ "${pacstrap_dir}/usr/share/edk2-shell/ia32/Shell_Full.efi")
+
+ if [[ ! " ${bootmodes[*]} " =~ uefi-x64.systemd-boot.esp ]]; then
+ efiboot_files+=("${pacstrap_dir}/boot/vmlinuz-"*
+ "${pacstrap_dir}/boot/initramfs-"*".img")
+
+ efiboot_imgsize="$(du -bc "${efiboot_files[@]}" \
+ 2>/dev/null | awk 'END { print $1 }')"
+ # Create a FAT image for the EFI system partition
+ _make_efibootimg "$efiboot_imgsize"
+ else
+ _run_once _make_bootmode_uefi-x64.systemd-boot.esp
+ fi
+
+ # Copy grub EFI binary to the default/fallback boot path
+ mcopy -i "${work_dir}/efiboot.img" \
+ "${work_dir}/BOOTIA32.EFI" ::/EFI/BOOT/BOOTIA32.EFI
+
+ # Copy GRUB configuration files
+ mcopy -i "${work_dir}/efiboot.img" \
+ "${work_dir}/grub.cfg" ::/EFI/BOOT/grub.cfg
+
+ # shellia32.efi is picked up automatically when on /
+ if [[ -e "${pacstrap_dir}/usr/share/edk2-shell/ia32/Shell_Full.efi" ]]; then
+ mcopy -i "${work_dir}/efiboot.img" \
+ "${pacstrap_dir}/usr/share/edk2-shell/ia32/Shell_Full.efi" ::/shellia32.efi
+ fi
+
+ _msg_info "Done! GRUB set up for UEFI booting successfully."
+}
+
+# Prepare GRUB for El Torito booting
+_make_bootmode_uefi-ia32.grub.eltorito() {
+ # El Torito UEFI boot requires an image containing the EFI system partition.
+ # uefi-ia32.grub.eltorito has the same requirements as uefi-ia32.grub.esp
+ _run_once _make_bootmode_uefi-ia32.grub.esp
+
+ # Additionally set up system-boot in ISO 9660. This allows creating a medium for the live environment by using
+ # manual partitioning and simply copying the ISO 9660 file system contents.
+ # This is not related to El Torito booting and no firmware uses these files.
+ _msg_info "Preparing an /EFI directory for the ISO 9660 file system..."
+ install -d -m 0755 -- "${isofs_dir}/EFI/BOOT"
+
+ # Copy GRUB EFI binary to the default/fallback boot path
+ install -m 0644 -- "${work_dir}/BOOTIA32.EFI" \
+ "${isofs_dir}/EFI/BOOT/BOOTIA32.EFI"
+
+ # Copy GRUB configuration files
+ install -m 0644 -- "${work_dir}/grub.cfg" "${isofs_dir}/EFI/BOOT/grub.cfg"
+
+ # edk2-shell based UEFI shell
+ # shellia32.efi is picked up automatically when on /
+ if [[ -e "${pacstrap_dir}/usr/share/edk2-shell/ia32/Shell_Full.efi" ]]; then
+ install -m 0644 -- "${pacstrap_dir}/usr/share/edk2-shell/ia32/Shell_Full.efi" \
+ "${isofs_dir}/shellia32.efi"
+ fi
+
+ _msg_info "Done!"
+}
+
# Prepare system-boot for booting when written to a disk (isohybrid)
_make_bootmode_uefi-x64.systemd-boot.esp() {
local _file efiboot_imgsize
@@ -530,13 +609,13 @@ _make_bootmode_uefi-x64.systemd-boot.esp() {
fi
done
# Calculate the required FAT image size in bytes
- efiboot_imgsize="$(du -bc \
- "${pacstrap_dir}/usr/lib/systemd/boot/efi/systemd-bootx64.efi" \
- "${pacstrap_dir}/usr/share/edk2-shell/x64/Shell_Full.efi" \
- "${profile}/efiboot/" \
- "${pacstrap_dir}/boot/vmlinuz-"* \
- "${pacstrap_dir}/boot/initramfs-"*".img" \
- "${_available_ucodes[@]}" \
+ efiboot_files+=("${pacstrap_dir}/usr/lib/systemd/boot/efi/systemd-bootx64.efi"
+ "${pacstrap_dir}/usr/share/edk2-shell/x64/Shell_Full.efi"
+ "${profile}/efiboot/"
+ "${pacstrap_dir}/boot/vmlinuz-"*
+ "${pacstrap_dir}/boot/initramfs-"*".img"
+ "${_available_ucodes[@]}")
+ efiboot_imgsize="$(du -bc "${efiboot_files[@]}" \
2>/dev/null | awk 'END { print $1 }')"
# Create a FAT image for the EFI system partition
_make_efibootimg "$efiboot_imgsize"
@@ -691,6 +770,20 @@ _validate_requirements_bootmode_uefi-x64.systemd-boot.eltorito() {
_validate_requirements_bootmode_uefi-x64.systemd-boot.esp
}
+_validate_requirements_bootmode_uefi-ia32.grub.esp() {
+ # Check if GRUB is available
+ if ! command -v grub-mkstandalone &> /dev/null; then
+ (( validation_error=validation_error+1 ))
+ _msg_error "Validating '${bootmode}': grub-install is not available on this host. Install 'grub'!" 0
+ fi
+ _validate_requirements_bootmode_uefi-x64.systemd-boot.esp
+}
+
+_validate_requirements_bootmode_uefi-ia32.grub.eltorito() {
+ # uefi-ia32.grub.eltorito has the exact same requirements as uefi-ia32.grub.esp
+ _validate_requirements_bootmode_uefi-ia32.grub.esp
+}
+
# Build airootfs filesystem image
_prepare_airootfs_image() {
_run_once "_mkairootfs_${airootfs_image_type}"
@@ -909,6 +1002,22 @@ _add_xorrisofs_options_bios.syslinux.mbr() {
)
}
+# GRUB in an attached EFI system partition
+_add_xorrisofs_options_uefi-ia32.grub.esp() {
+ # shellcheck disable=SC2076
+ if [[ ! " ${bootmodes[*]} " =~ ' uefi-x64.systemd-boot.esp ' ]]; then
+ _add_xorrisofs_options_uefi-x64.systemd-boot.esp
+ fi
+}
+
+# GRUB via El Torito
+_add_xorrisofs_options_uefi-ia32.grub.eltorito() {
+ # shellcheck disable=SC2076
+ if [[ ! " ${bootmodes[*]} " =~ ' uefi-x64.systemd-boot.eltorito ' ]]; then
+ _add_xorrisofs_options_uefi-x64.systemd-boot.eltorito
+ fi
+}
+
# systemd-boot in an attached EFI system partition
_add_xorrisofs_options_uefi-x64.systemd-boot.esp() {
# Move the first partition away from the start of the ISO, otherwise the GPT will not be valid and ISO 9660
@@ -923,7 +1032,7 @@ _add_xorrisofs_options_uefi-x64.systemd-boot.esp() {
# A valid GPT prevents BIOS booting on some systems, instead use an invalid GPT (without a protective MBR).
# The attached partition will have the EFI system partition type code in MBR, but in the invalid GPT it will
# have a Microsoft basic partition type code.
- if [[ ! " ${bootmodes[*]} " =~ ' uefi-x64.systemd-boot.eltorito ' ]]; then
+ if [[ ! " ${bootmodes[*]} " =~ ' uefi-x64.systemd-boot.eltorito ' && ! " ${bootmodes[*]} " =~ ' uefi-ia32.grub.eltorito ' ]]; then
# If '-isohybrid-gpt-basdat' is specified before '-e', then the appended EFI system partition will have the
# EFI system partition type ID/GUID in both MBR and GPT. If '-isohybrid-gpt-basdat' is specified after '-e',
# the appended EFI system partition will have the Microsoft basic data type GUID in GPT.
@@ -940,7 +1049,7 @@ _add_xorrisofs_options_uefi-x64.systemd-boot.esp() {
# systemd-boot via El Torito
_add_xorrisofs_options_uefi-x64.systemd-boot.eltorito() {
# shellcheck disable=SC2076
- if [[ " ${bootmodes[*]} " =~ ' uefi-x64.systemd-boot.esp ' ]]; then
+ if [[ " ${bootmodes[*]} " =~ ' uefi-x64.systemd-boot.esp ' || " ${bootmodes[*]} " =~ ' uefi-ia32.grub.esp ' ]]; then
# systemd-boot in an attached EFI system partition via El Torito
xorrisofs_options+=(
# Start a new El Torito boot entry for UEFI
diff --git a/configs/baseline/grub/grub.cfg b/configs/baseline/grub/grub.cfg
new file mode 100644
index 0000000..0e5db49
--- /dev/null
+++ b/configs/baseline/grub/grub.cfg
@@ -0,0 +1,29 @@
+insmod part_gpt
+insmod part_msdos
+insmod fat
+insmod iso9660
+
+insmod all_video
+
+insmod font
+
+if loadfont "${prefix}/fonts/unicode.pf2" ; then
+ insmod gfxterm
+ set gfxmode="auto"
+ terminal_input console
+ terminal_output gfxterm
+fi
+
+menuentry "Arch Linux (x86_64, UEFI)" {
+ set gfxpayload=keep
+ search --no-floppy --set=root --label %ARCHISO_LABEL%
+ linux /%INSTALL_DIR%/boot/x86_64/vmlinuz-linux archisobasedir=%INSTALL_DIR% archisolabel=%ARCHISO_LABEL%
+ initrd /%INSTALL_DIR%/boot/x86_64/initramfs-linux.img
+}
+
+menuentry "Arch Linux (x86_64, UEFI) Copy to RAM" {
+ set gfxpayload=keep
+ search --no-floppy --set=root --label %ARCHISO_LABEL%
+ linux /%INSTALL_DIR%/boot/x86_64/vmlinuz-linux archisobasedir=%INSTALL_DIR% archisolabel=%ARCHISO_LABEL% copytoram
+ initrd /%INSTALL_DIR%/boot/x86_64/initramfs-linux.img
+}
diff --git a/configs/baseline/profiledef.sh b/configs/baseline/profiledef.sh
index d376516..34060f2 100644
--- a/configs/baseline/profiledef.sh
+++ b/configs/baseline/profiledef.sh
@@ -8,7 +8,9 @@ iso_application="Arch Linux baseline"
iso_version="$(date +%Y.%m.%d)"
install_dir="arch"
buildmodes=('iso')
-bootmodes=('bios.syslinux.mbr' 'bios.syslinux.eltorito' 'uefi-x64.systemd-boot.esp' 'uefi-x64.systemd-boot.eltorito')
+bootmodes=('bios.syslinux.mbr' 'bios.syslinux.eltorito'
+ 'uefi-ia32.grub.esp' 'uefi-x64.systemd-boot.esp'
+ 'uefi-ia32.grub.eltorito' 'uefi-x64.systemd-boot.eltorito')
arch="x86_64"
pacman_conf="pacman.conf"
airootfs_image_type="erofs"
diff --git a/configs/releng/efiboot/loader/entries/01-archiso-x86_64-linux.conf b/configs/releng/efiboot/loader/entries/01-archiso-x86_64-linux.conf
index d59262f..1c2a7a8 100644
--- a/configs/releng/efiboot/loader/entries/01-archiso-x86_64-linux.conf
+++ b/configs/releng/efiboot/loader/entries/01-archiso-x86_64-linux.conf
@@ -1,6 +1,7 @@
-title Arch Linux install medium (x86_64, UEFI)
-linux /%INSTALL_DIR%/boot/x86_64/vmlinuz-linux
-initrd /%INSTALL_DIR%/boot/intel-ucode.img
-initrd /%INSTALL_DIR%/boot/amd-ucode.img
-initrd /%INSTALL_DIR%/boot/x86_64/initramfs-linux.img
-options archisobasedir=%INSTALL_DIR% archisolabel=%ARCHISO_LABEL%
+title Arch Linux install medium (x86_64, UEFI)
+sort-key 01
+linux /%INSTALL_DIR%/boot/x86_64/vmlinuz-linux
+initrd /%INSTALL_DIR%/boot/intel-ucode.img
+initrd /%INSTALL_DIR%/boot/amd-ucode.img
+initrd /%INSTALL_DIR%/boot/x86_64/initramfs-linux.img
+options archisobasedir=%INSTALL_DIR% archisolabel=%ARCHISO_LABEL%
diff --git a/configs/releng/efiboot/loader/entries/02-archiso-x86_64-speech-linux.conf b/configs/releng/efiboot/loader/entries/02-archiso-x86_64-speech-linux.conf
index 06f5466..64253d3 100644
--- a/configs/releng/efiboot/loader/entries/02-archiso-x86_64-speech-linux.conf
+++ b/configs/releng/efiboot/loader/entries/02-archiso-x86_64-speech-linux.conf
@@ -1,6 +1,7 @@
-title Arch Linux install medium (x86_64, UEFI) with speech
-linux /%INSTALL_DIR%/boot/x86_64/vmlinuz-linux
-initrd /%INSTALL_DIR%/boot/intel-ucode.img
-initrd /%INSTALL_DIR%/boot/amd-ucode.img
-initrd /%INSTALL_DIR%/boot/x86_64/initramfs-linux.img
-options archisobasedir=%INSTALL_DIR% archisolabel=%ARCHISO_LABEL% accessibility=on
+title Arch Linux install medium (x86_64, UEFI) with speech
+sort-key 02
+linux /%INSTALL_DIR%/boot/x86_64/vmlinuz-linux
+initrd /%INSTALL_DIR%/boot/intel-ucode.img
+initrd /%INSTALL_DIR%/boot/amd-ucode.img
+initrd /%INSTALL_DIR%/boot/x86_64/initramfs-linux.img
+options archisobasedir=%INSTALL_DIR% archisolabel=%ARCHISO_LABEL% accessibility=on
diff --git a/configs/releng/efiboot/loader/entries/03-archiso-x86_64-ram-linux.conf b/configs/releng/efiboot/loader/entries/03-archiso-x86_64-ram-linux.conf
index 9c7a51a..3e26651 100644
--- a/configs/releng/efiboot/loader/entries/03-archiso-x86_64-ram-linux.conf
+++ b/configs/releng/efiboot/loader/entries/03-archiso-x86_64-ram-linux.conf
@@ -1,6 +1,7 @@
-title Arch Linux install medium (x86_64, UEFI, Copy to RAM)
-linux /%INSTALL_DIR%/boot/x86_64/vmlinuz-linux
-initrd /%INSTALL_DIR%/boot/intel-ucode.img
-initrd /%INSTALL_DIR%/boot/amd-ucode.img
-initrd /%INSTALL_DIR%/boot/x86_64/initramfs-linux.img
-options archisobasedir=%INSTALL_DIR% archisolabel=%ARCHISO_LABEL% copytoram
+title Arch Linux install medium (x86_64, UEFI, Copy to RAM)
+sort-key 03
+linux /%INSTALL_DIR%/boot/x86_64/vmlinuz-linux
+initrd /%INSTALL_DIR%/boot/intel-ucode.img
+initrd /%INSTALL_DIR%/boot/amd-ucode.img
+initrd /%INSTALL_DIR%/boot/x86_64/initramfs-linux.img
+options archisobasedir=%INSTALL_DIR% archisolabel=%ARCHISO_LABEL% copytoram
diff --git a/configs/releng/efiboot/loader/entries/04-archiso-x86_64-ram-speech-linux.conf b/configs/releng/efiboot/loader/entries/04-archiso-x86_64-ram-speech-linux.conf
new file mode 100644
index 0000000..0d67999
--- /dev/null
+++ b/configs/releng/efiboot/loader/entries/04-archiso-x86_64-ram-speech-linux.conf
@@ -0,0 +1,7 @@
+title Arch Linux install medium (x86_64, UEFI, Copy to RAM) with speech
+sort-key 04
+linux /%INSTALL_DIR%/boot/x86_64/vmlinuz-linux
+initrd /%INSTALL_DIR%/boot/intel-ucode.img
+initrd /%INSTALL_DIR%/boot/amd-ucode.img
+initrd /%INSTALL_DIR%/boot/x86_64/initramfs-linux.img
+options archisobasedir=%INSTALL_DIR% archisolabel=%ARCHISO_LABEL% copytoram accessibility=on
diff --git a/configs/releng/efiboot/loader/loader.conf b/configs/releng/efiboot/loader/loader.conf
index ae63487..2d137aa 100644
--- a/configs/releng/efiboot/loader/loader.conf
+++ b/configs/releng/efiboot/loader/loader.conf
@@ -1,2 +1,3 @@
timeout 15
default 01-archiso-x86_64-linux.conf
+beep on
diff --git a/configs/releng/grub/grub.cfg b/configs/releng/grub/grub.cfg
new file mode 100644
index 0000000..4a707b9
--- /dev/null
+++ b/configs/releng/grub/grub.cfg
@@ -0,0 +1,46 @@
+insmod part_gpt
+insmod part_msdos
+insmod fat
+insmod iso9660
+
+insmod all_video
+
+insmod font
+
+if loadfont "${prefix}/fonts/unicode.pf2" ; then
+ insmod gfxterm
+ set gfxmode="auto"
+ terminal_input console
+ terminal_output gfxterm
+fi
+
+# GRUB init tune for accessibility
+#
+# Morse translation table:
+# "." is "500 1 300 1"
+# "-" is "600 3 300 1"
+# " " is "100 2"
+# "/" is "100 5"
+#
+# Message: "s for blind"
+play 500 500 1 300 1 500 1 300 1 500 1 300 1 100 5 500 1 300 1 500 1 300 1 100 2 500 1 300 1 500 1 300 1 600 3 300 1 500 1 300 1 100 5 600 3 300 1 500 1 300 1 500 1 300 1 500 1 300 1 100 2 500 1 300 1 600 3 300 1 500 1 300 1 500 1 300 1 100 2 500 1 300 1 500 1 300 1 100 2 500 1 300 1 500 1 300 1 100 2 600 3 300 1 500 1 300 1 100 2 600 3 300 1 500 1 300 1 500 1 300 1
+
+menuentry "Arch Linux install medium (x86_64, UEFI)" {
+ set gfxpayload=keep
+ search --no-floppy --set=root --label %ARCHISO_LABEL%
+ linux /%INSTALL_DIR%/boot/x86_64/vmlinuz-linux archisobasedir=%INSTALL_DIR% archisolabel=%ARCHISO_LABEL%
+ initrd /%INSTALL_DIR%/boot/intel-ucode.img /%INSTALL_DIR%/boot/amd-ucode.img /%INSTALL_DIR%/boot/x86_64/initramfs-linux.img
+}
+
+menuentry "Arch Linux install medium with speakup screen reader (x86_64, UEFI)" --hotkey=s {
+ set gfxpayload=keep
+ search --no-floppy --set=root --label %ARCHISO_LABEL%
+ linux /%INSTALL_DIR%/boot/x86_64/vmlinuz-linux archisobasedir=%INSTALL_DIR% archisolabel=%ARCHISO_LABEL% accessibility=on
+ initrd /%INSTALL_DIR%/boot/intel-ucode.img /%INSTALL_DIR%/boot/amd-ucode.img /%INSTALL_DIR%/boot/x86_64/initramfs-linux.img
+}
+
+menuentry "UEFI Shell" {
+ insmod chain
+ search --no-floppy --set=root --label %ARCHISO_LABEL%
+ chainloader /shellia32.efi
+}
diff --git a/configs/releng/packages.x86_64 b/configs/releng/packages.x86_64
index 511f452..8a0c80d 100644
--- a/configs/releng/packages.x86_64
+++ b/configs/releng/packages.x86_64
@@ -4,7 +4,7 @@ arch-install-scripts
archinstall
b43-fwcutter
base
-bind-tools
+bind
brltty
broadcom-wl
btrfs-progs
diff --git a/docs/README.profile.rst b/docs/README.profile.rst
index c93228d..a3d4309 100644
--- a/docs/README.profile.rst
+++ b/docs/README.profile.rst
@@ -10,6 +10,7 @@ An archiso profile consists of several configuration files and a directory for f
├── airootfs/
├── efiboot/
├── syslinux/
+ ├── grub/
├── bootstrap_packages.arch
├── packages.arch
├── pacman.conf
@@ -45,6 +46,8 @@ The image file is constructed from some of the variables in ``profiledef.sh``: `
- ``bios.syslinux.mbr``: Syslinux for x86 BIOS booting from a disk
- ``bios.syslinux.eltorito``: Syslinux for x86 BIOS booting from an optical disc
+ - ``uefi-ia32.grub.esp``: GRUB for IA32 UEFI booting from a disk
+ - ``uefi-ia32.grub.eltorito``: GRUB for IA32 UEFI booting from an optical disc
- ``uefi-x64.systemd-boot.esp``: systemd-boot for x86_64 UEFI booting from a disk
- ``uefi-x64.systemd-boot.eltorito``: systemd-boot for x86_64 UEFI booting from an optical disc
Note that BIOS El Torito boot mode must always be listed before UEFI El Torito boot mode.
@@ -158,6 +161,14 @@ This directory is mandatory when the ``bios.syslinux.mbr`` or the ``bios.syslinu
``profiledef.sh``.
It contains configuration files for `syslinux <https://wiki.syslinux.org/wiki/index.php?title=SYSLINUX>`_ or `isolinux
<https://wiki.syslinux.org/wiki/index.php?title=ISOLINUX>`_ , or `pxelinux
-<https://wiki.syslinux.org/wiki/index.php?title=PXELINUX>`_ used in the resuling image.
+<https://wiki.syslinux.org/wiki/index.php?title=PXELINUX>`_ used in the resulting image.
The *custom template identifiers* are understood in all `.cfg` files in this directory.
+
+grub
+----
+
+This directory is mandatory when the ``uefi-ia32.grub.esp`` or ``uefi-ia32.grub.eltorito`` bootmodes are selected in
+``profiledef.sh``.
+It contains configuration files for `GRUB <https://www.gnu.org/software/grub/>`_
+used in the resulting image.