use mkinitcpio's UKI generation instead of doing it manually via objcopy

runner.vm/Dockerfile.root

@@ -1,13 +1,12 @@
 FROM archlinux AS builder
-RUN pacman -Syyu --noconfirm && pacman --noconfirm -S mkinitcpio
-RUN sed -i 's/MODULES=()/MODULES=(ext4 virtio virtio_pci virtio_net virtio_scsi)/' /etc/mkinitcpio.conf
-RUN pacman --noconfirm -S dhcpcd \
-                          docker \
+COPY files/ /
+RUN pacman -Syyu --noconfirm
+RUN pacman --noconfirm -S docker \
                           docker-buildx \
                           git \
                           jq \
-                          linux
-COPY files/ /
+                          linux \
+                          mkinitcpio
 
 RUN systemctl enable gcpnetwork.service docker.service runner.service limit.timer
 RUN systemctl disable systemd-networkd systemd-timesyncd systemd-resolved
@@ -22,6 +21,4 @@ RUN truncate -s ${ROOT_PART_SIZE}MiB /rootfs.raw && mkfs.ext4 -E lazy_itable_ini
 
 FROM scratch AS exportfs
 COPY --from=buildfs /rootfs.raw /
-COPY --from=builder /boot/initramfs-linux.img /
-COPY --from=builder /boot/vmlinuz-linux /
-COPY --from=builder /usr/lib/systemd/boot/efi/linuxx64.efi.stub /
+COPY --from=builder /boot/arch.efi /

runner.vm/build.sh

@@ -8,27 +8,22 @@ if [ -n "$TAR_FILENAME" ]; then
    case "$TAR_FILENAME" in
       rootfs.raw)
          dd bs=${ESP_SIZE}MiB seek=1 of=disk.raw conv=notrunc status=none;;
+      arch.efi)
+         mcopy -i disk.raw@@2M - ::/EFI/BOOT/BOOTX64.EFI;;
       *)
-         cat > "$TAR_FILENAME";;
+         echo "Unexpected file in output: $TAR_FILENAME" && exit 1;;
    esac
    exit 0
 fi
 
-rm disk.raw
+[ -f disk.raw ] && echo "disk.raw already exists; need to remove before running script" && exit 1
 
 truncate -s $(($ESP_SIZE - 2))MiB disk.raw
 mformat -i disk.raw@@2M -F
+mmd -i disk.raw@@2M ::/EFI
+mmd -i disk.raw@@2M ::/EFI/BOOT
 truncate -s ${DISK_SIZE}MiB disk.raw
 parted disk.raw -s mklabel gpt mkpart EFI 2MiB ${ESP_SIZE}MiB mkpart root ${ESP_SIZE}MiB 100% set 1 esp
 
 DOCKER_BUILDKIT=1 docker build --no-cache -o - -q --build-arg ROOT_PART_SIZE=$(($DISK_SIZE - $ESP_SIZE - 1)) -f Dockerfile.root . | tar x --to-command="$BASH_SOURCE"
 
-objcopy \
-   --add-section .cmdline="cmdline.txt" --change-section-vma .cmdline=0x30000 \
-   --add-section .linux="vmlinuz-linux" --change-section-vma .linux=0x40000 \
-   --add-section .initrd="initramfs-linux.img" --change-section-vma .initrd=0x3000000 \
-   linuxx64.efi.stub BOOTX64.EFI
-
-mmd -i disk.raw@@2M ::/EFI
-mmd -i disk.raw@@2M ::/EFI/BOOT
-mcopy -i disk.raw@@2M BOOTX64.EFI ::/EFI/BOOT

runner.vm/files/etc/mkinitcpio.conf

@@ -0,0 +1,9 @@
+# by default mkinitcpio will auto-detect host modules,
+# make sure required modules for a VM environment are included
+MODULES=(ext4 virtio virtio_pci virtio_net virtio_scsi)
+
+# rest of the settings are default
+BINARIES=()
+FILES=()
+HOOKS=(base udev autodetect modconf kms keyboard keymap consolefont block filesystems fsck)
+

runner.vm/files/etc/mkinitcpio.d/linux.preset

@@ -0,0 +1,9 @@
+ALL_config="/etc/mkinitcpio.conf"
+ALL_kver="/boot/vmlinuz-linux"
+ALL_microcode=(/boot/*-ucode.img)
+
+PRESETS=('default')
+
+default_image="/boot/initramfs-linux.img"
+default_uki="/boot/arch.efi"
+