From dc090c1fae9840938bd8c29f569b6f26badfd0b4 Mon Sep 17 00:00:00 2001
From: nl6720 <nl6720@gmail.com>
Date: Sun, 17 Mar 2024 15:10:50 +0200
Subject: [PATCH] mkarchiso: skip including external microcode images if the
 initramfs file contains early_cpio

The early uncompressed CPIO archive containing microcode update files
can be part of the initramfs file. To avoid wasting space, first check
if the initramfs file contains `early_cpio` and only copy external
microcode initramfs images if it does not.
---
 CHANGELOG.rst     |  2 ++
 archiso/mkarchiso | 62 +++++++++++++++++++++++++++++++----------------
 2 files changed, 43 insertions(+), 21 deletions(-)

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index c316aed..40961be 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -16,6 +16,8 @@ Changed
 - Move ``/boot/grub/YYYY-mm-dd-HH-MM-SS-00.uuid`` to ``/boot/YYYY-mm-dd-HH-MM-SS-00.uuid`` and always create the file.
   Once mkinitcpio-archiso implements searching for the file in early userspace, this file's use will not be limited to
   just GRUB.
+- Skip including external microcode images in build artifacts if the initramfs file contains ``early_cpio`` (indicating
+  an early uncompressed CPIO archive which should have the microcode update files).
 
 Deprecated
 ----------
diff --git a/archiso/mkarchiso b/archiso/mkarchiso
index 80d4a79..dbae227 100755
--- a/archiso/mkarchiso
+++ b/archiso/mkarchiso
@@ -46,6 +46,7 @@ efibootimg=""
 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')
+declare -i need_external_ucodes=0
 
 
 # Show an INFO message
@@ -430,17 +431,18 @@ _make_boot_on_iso9660() {
     install -m 0644 -- "${pacstrap_dir}/boot/initramfs-"*".img" "${isofs_dir}/${install_dir}/boot/${arch}/"
     install -m 0644 -- "${pacstrap_dir}/boot/vmlinuz-"* "${isofs_dir}/${install_dir}/boot/${arch}/"
 
-    for ucode_image in "${ucodes[@]}"; do
-        if [[ -e "${pacstrap_dir}/boot/${ucode_image}" ]]; then
-            install -m 0644 -- "${pacstrap_dir}/boot/${ucode_image}" "${isofs_dir}/${install_dir}/boot/"
-            if [[ -e "${pacstrap_dir}/usr/share/licenses/${ucode_image%.*}/" ]]; then
-                install -d -m 0755 -- "${isofs_dir}/${install_dir}/boot/licenses/${ucode_image%.*}/"
-                install -m 0644 -- "${pacstrap_dir}/usr/share/licenses/${ucode_image%.*}/"* \
-                    "${isofs_dir}/${install_dir}/boot/licenses/${ucode_image%.*}/"
+    if (( need_external_ucodes )); then
+        for ucode_image in "${ucodes[@]}"; do
+            if [[ -e "${pacstrap_dir}/boot/${ucode_image}" ]]; then
+                install -m 0644 -- "${pacstrap_dir}/boot/${ucode_image}" "${isofs_dir}/${install_dir}/boot/"
+                if [[ -e "${pacstrap_dir}/usr/share/licenses/${ucode_image%.*}/" ]]; then
+                    install -d -m 0755 -- "${isofs_dir}/${install_dir}/boot/licenses/${ucode_image%.*}/"
+                    install -m 0644 -- "${pacstrap_dir}/usr/share/licenses/${ucode_image%.*}/"* \
+                        "${isofs_dir}/${install_dir}/boot/licenses/${ucode_image%.*}/"
+                fi
             fi
-        fi
-    done
-
+        done
+    fi
     _msg_info "Done!"
 }
 
@@ -505,13 +507,15 @@ _make_boot_on_fat() {
         "::/${install_dir}" "::/${install_dir}/boot" "::/${install_dir}/boot/${arch}"
     mcopy -i "${efibootimg}" "${pacstrap_dir}/boot/vmlinuz-"* \
         "${pacstrap_dir}/boot/initramfs-"*".img" "::/${install_dir}/boot/${arch}/"
-    for ucode_image in "${ucodes[@]}"; do
-        if [[ -e "${pacstrap_dir}/boot/${ucode_image}" ]]; then
-            all_ucode_images+=("${pacstrap_dir}/boot/${ucode_image}")
+    if (( need_external_ucodes )); then
+        for ucode_image in "${ucodes[@]}"; do
+            if [[ -e "${pacstrap_dir}/boot/${ucode_image}" ]]; then
+                all_ucode_images+=("${pacstrap_dir}/boot/${ucode_image}")
+            fi
+        done
+        if (( ${#all_ucode_images[@]} )); then
+            mcopy -i "${efibootimg}" "${all_ucode_images[@]}" "::/${install_dir}/boot/"
         fi
-    done
-    if (( ${#all_ucode_images[@]} )); then
-        mcopy -i "${efibootimg}" "${all_ucode_images[@]}" "::/${install_dir}/boot/"
     fi
     _msg_info "Done!"
 }
@@ -550,6 +554,19 @@ _make_efibootimg() {
     mmd -i "${efibootimg}" ::/EFI ::/EFI/BOOT
 }
 
+# Check if initramfs files contain early_cpio
+_check_if_initramfs_has_early_cpio() {
+    local initrd
+
+    for initrd in $(compgen -G "${pacstrap_dir}"'/boot/initramfs-*.img'); do
+        if ! bsdtar -tf "$initrd" early_cpio &>/dev/null; then
+            need_external_ucodes=1
+            _msg_info "Initramfs file does not contain 'early_cpio'. External microcode initramfs images will be copied."
+            return
+        fi
+    done
+}
+
 # Copy GRUB files to ISO 9660 which is used by both IA32 UEFI and x64 UEFI
 _make_common_bootmode_grub_copy_to_isofs() {
     local files_to_copy=()
@@ -819,11 +836,13 @@ _make_common_bootmode_systemd-boot() {
     local _file efiboot_imgsize
     local _available_ucodes=()
 
-    for _file in "${ucodes[@]}"; do
-        if [[ -e "${pacstrap_dir}/boot/${_file}" ]]; then
-            _available_ucodes+=("${pacstrap_dir}/boot/${_file}")
-        fi
-    done
+    if (( need_external_ucodes )); then
+        for _file in "${ucodes[@]}"; do
+            if [[ -e "${pacstrap_dir}/boot/${_file}" ]]; then
+                _available_ucodes+=("${pacstrap_dir}/boot/${_file}")
+            fi
+        done
+    fi
     # Calculate the required FAT image size in bytes
     # shellcheck disable=SC2076
     if [[ " ${bootmodes[*]} " =~ ' uefi-x64.systemd-boot.esp ' || " ${bootmodes[*]} " =~ ' uefi-x64.systemd-boot.eltorito ' ]]; then
@@ -1914,6 +1933,7 @@ _build_iso_base() {
     _run_once _make_version
     _run_once _make_customize_airootfs
     _run_once _make_pkglist
+    _run_once _check_if_initramfs_has_early_cpio
     if [[ "${buildmode}" == 'netboot' ]]; then
         _run_once _make_boot_on_iso9660
     else