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How to Make a USB UEFI?

Published in UEFI Bootable USB 4 mins read

Making a USB UEFI bootable typically involves formatting the drive correctly and placing specific bootloader files on it, allowing your system's UEFI firmware to recognize and boot from the device. Based on the provided reference, here is a straightforward method to create a basic UEFI bootable USB, often used for launching the UEFI Shell or similar minimal environments.

This process details how to prepare a USB drive that your system's UEFI firmware can detect and boot from, specifically by placing a UEFI executable file in the standard boot location.

Step-by-Step Guide: Creating a UEFI Shell Bootable USB

Follow these steps to prepare your USB drive according to the method described in the reference:

  1. Format the USB Device in FAT32:

    • Ensure your USB flash drive is formatted with the FAT32 file system. This is a crucial requirement for most UEFI implementations to recognize and boot from external devices.
    • Practical Insight: You can do this using Disk Management in Windows, Disk Utility in macOS, or tools like mkfs.fat in Linux.

  2. Create Directory Structure:

    • On the root of your freshly formatted USB drive, create a directory named /efi.
    • Inside the /efi directory, create another directory named /boot.
    • The final path should be /efi/boot/.

  3. Copy the UEFI Executable File:

    • Obtain the shell.efi file (or any other desired UEFI bootable .efi application you want to run). This file is the executable that the UEFI firmware will launch.
    • Copy the file shell.efi into the directory you created in the previous step: /efi/boot/.

  4. Rename the Executable File:

    • Rename the shell.efi file you just copied to BOOTX64.efi.
    • Why? BOOTX64.efi is the standard default name and location (/efi/boot/) that UEFI firmware on x64 (64-bit) systems automatically looks for when trying to boot from a device. This makes the USB automatically detectable as a bootable UEFI device.

Understanding the Process

This method leverages the standard UEFI boot sequence. The FAT32 format is readable by the firmware, and the /efi/boot/BOOTX64.efi path is the conventional place the firmware checks for a bootable application on removable media for 64-bit systems. By placing the shell.efi (or another UEFI application) at this location and renaming it, you create a USB drive that can be automatically recognized and booted by a UEFI system.

How to Boot from the Prepared USB

Once your USB drive is prepared:

  1. Restart Your System and Enter the UEFI Menu:

    • Restart your computer. As it starts up, repeatedly press the key designated to enter the BIOS/UEFI setup or boot menu (common keys include F2, F10, F12, Del, or Esc – consult your motherboard or computer manual).

  2. Select the Option to Boot from USB:

    • Navigate the UEFI menu to find the boot options.
    • Select your USB device from the list of available boot drives. It might be listed by its model name, or sometimes simply as "USB UEFI OS" or "UEFI: [USB Drive Name]".

Upon selecting the USB, the UEFI firmware should load and execute the BOOTX64.efi file located at /efi/boot/ on the drive.

This manual method is useful for creating basic UEFI bootable media, such as for diagnostics or running specific UEFI applications like the UEFI Shell, without needing complex tools.

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