HackBGRT is intended as a boot logo changer for UEFI-based Windows systems.

When booting on a UEFI-based computer, Windows may show a vendor-defined logo which is stored on the UEFI firmware in a section called Boot Graphics Resource Table (BGRT). It's usually very difficult to change the image permanently, but a custom UEFI application may be used to overwrite it during the boot. HackBGRT does exactly that.

Note: The original logo is often visible for a moment before HackBGRT is started. This is expected, please do not report this "bug". This can't be changed without modifying computer firmware, which this project will not do.

Important: If you mess up the installation, your system may become unbootable! Create a rescue disk before use. This software comes with no warranty. Use at your own risk.

• Make sure that your computer is booting with UEFI.
• Make sure that you have read the Secure Boot instructions.
• Make sure that BitLocker is disabled, or find your recovery key.

HackBGRT is not approved by Microsoft. Instead, HackBGRT comes with the shim boot loader, which allows to manually select HackBGRT as a trusted program. After installing HackBGRT and rebooting your computer, you have to follow the instructions in shim.md to achieve this. These steps cannot be automated, that's the whole point of Secure Boot. Although HackBGRT is self-signed with a certificate, it's not advisable to enroll foreign certificates directly into your firmware.

The shim boot loader is maintained by Red Hat, Inc, and the included signed copy of shim is extracted from Debian GNU/Linux – many thanks to the maintainers! For copyright information, see shim-signed/COPYRIGHT.

• Get the latest release from the Releases page.
• Start setup.exe and follow the instructions.
  • The installer will launch Paint for editing the image, or you can edit it otherwise.
  • For advanced settings, edit config.txt before installing. No extra support provided!
  • Read the instructions in shim.md.
  • Check the common troubleshooting to be prepared.
  • Reboot your computer.
• If Windows later restores the original boot loader, just reinstall.
• If you wish to change the image or configuration later, choose the option to only install files.

• Edit the config.txt and splash.bmp (or any other images) to your needs.
• Run setup.exe batch COMMANDS as administrator, with some of the following commands:
  • install – copy the files but don't enable.
  • enable-bcdedit – use bcdedit to create a new EFI boot entry.
  • disable-bcdedit – use bcdedit to disable the EFI boot entry.
  • enable-entry – write NVRAM to create a new EFI boot entry.
  • disable-entry – write NVRAM to disable the EFI boot entry.
  • enable-overwrite – overwrite the MS boot loader.
  • disable-overwrite – restore the MS boot loader.
  • skip-shim – skip shim when installing.
  • allow-secure-boot – ignore Secure Boot in subsequent commands.
  • allow-bitlocker – ignore BitLocker in subsequent commands.
  • allow-bad-loader – ignore bad boot loader configuration in subsequent commands.
  • disable – run all relevant disable-* commands.
  • uninstall – disable and remove completely.
  • show-boot-log – show the debug log collected during boot (if log=1 is set in config.txt).
• For example, run setup.exe batch install allow-secure-boot enable-overwrite to copy files and overwrite the MS boot loader regardless of Secure Boot status.

If you only need HackBGRT for Windows:

• Run setup.exe, install files without enabling.
• Configure your boot loader to start \EFI\HackBGRT\loader.efi.

If you need it for other systems as well:

• Configure HackBGRT to start your boot loader (such as systemd-boot): boot=\EFI\systemd\systemd-bootx64.efi.
• Run setup.exe, install as a new EFI boot entry.

To install purely on Linux, you can install with setup.exe dry-run and then manually copy files from dry-run/EFI to your [EFI System Partition]/EFI. For further instructions, consult the documentation of your own Linux system.

The configuration options are described in config.txt, which the installer copies into [EFI System Partition]\EFI\HackBGRT\config.txt.

If you only need one image, just edit splash.bmp to your needs.

Advanced users may edit the config.txt to define multiple images, in which case one is picked at random. The installer copies and converts the images. For example, to use a file named my.jpg, copy it in the installer folder (same folder as setup.exe) and set the image path in config.txt to path=my.jpg before running the installer.

If you copy an image file to ESP manually, note that the image must be a 24-bit BMP file with a 54-byte header. That's a TrueColor BMP3 in Imagemagick, or 24-bit BMP/DIB in Microsoft Paint.

This is part of the setup on first boot. Make sure you have read and understood shim.md.

Sometimes the first boot is very slow (multiple minutes) for an unknown reason. Wait patiently until you get into Windows. Try to reboot at least a few times to see if it gets any better. It it does not, there's not much else to do than give up.

Run the setup again and select the option to check the boot log. Continue troubleshooting according to the log contents:

If the log is empty, then HackBGRT is not in use. Many computers now have a security feature which causes this problem: the computer resets some settings on reboot and skips the newly-installed HackBGRT.

You have to fix this manually. (After all, the security feature is specifically designed to prevent automatic changes.)

1. Run the setup again.
2. Select the option "boot to UEFI setup".
3. After a reboot, you should get into your computer's own setup utility (UEFI or Firmware settings, or so-called "BIOS").
4. Find boot options and the list of boot entries.
5. Select HackBGRT as the default boot entry (before Windows Boot Loader).

The setup utility is different for each computer and manufacturer, so search online for "[computer model] UEFI setup" or "firmware setup" for images and instructions.

Some people report that HackBGRT is not visible in the computer settings. That's unfortunately a problem with your computer, and you should ask your computer manufacturer how to edit boot entries inside your computer settings. HackBGRT needs to boot \EFI\HackBGRT\loader.efi.

If all else fails and you are sure about your computer skills, you can try the legacy installation method. The method bypasses this particular problem but may cause very serious problems if configured incorrectly.

Try to reinstall HackBGRT with the default configuration and image.

If the default logo works, try again with your custom image. Make sure that the image has a reasonable size and position and that you haven't messed up config.txt.

If the default logo does not work, check the boot log again. You may report an issue and attach the setup.log file.

If you used the default installation method, then your Windows boot loader is still in place and you should be able to access UEFI Setup ("BIOS setup") or boot loader list by some key combination right after powering on your computer. There you can choose the Windows Boot Loader and continue as usual to uninstall HackBGRT.

If you selected the legacy installation method which overwrites Windows boot loader, then you need to use the Windows installation disk (or recovery disk) to fix boot issues.

• Compiler: Clang
• Compiler flags: see Makefile
• Libraries: gnu-efi