DLC Boot is a Windows-based rescue and maintenance toolkit packaged as a bootable ISO. To use it on modern UEFI systems, follow these steps:
The Unified Extensible Firmware Interface (UEFI) replaced the legacy BIOS (Basic Input/Output System) over a decade ago. Key differences for bootable media:
.efi executables (e.g., bootx64.efi) stored on a FAT32 partition (ESP - EFI System Partition).Creating a UEFI-bootable ISO means the image must contain an EFI/BOOT/ directory with valid .efi binaries and a FAT16/FAT32 El Torito image. dlc boot uefi iso
Create a bios.img (floppy emulation or hard disk) or simply use GRUB's boot.img. For simplicity, we will let xorriso handle BIOS via a core image.
Start with a minimal live Linux (e.g., Debian Live, Archiso, or Alpine Linux). Create a root filesystem directory: Draft post: "DLC Boot UEFI ISO" (ready to
mkdir -p iso_root/live
debootstrap --arch=amd64 bullseye iso_root/chroot
chroot into iso_root, install kernel, systemd, grub-efi, squashfs-tools
Then squash the chroot:
mksquashfs iso_root/chroot iso_root/live/filesystem.squashfs -comp xz
Design your DLC as a compressed tarball or another squashfs. For example, a DLC containing custom systemd services: Partition Table: GPT (GUID Partition Table) instead of MBR
mkdir dlc_nvme
# Add NVMe CLI tools, udev rules, etc.
tar -czf nvme.dlc -C dlc_nvme .
Place these .dlc files inside iso_root/EFI/DLC/ or a dedicated /dlc/ directory on the ISO.
Most tutorials show you how to create a "multi-boot USB." That is easy. But creating a read-only ISO that can later accept new DLC without being remastered is the holy grail. Why? Because you might burn the ISO to a DVD (read-only) or a Write-Protected USB. You need the bootloader to be smart enough to look outside the ISO for additional content.