# HackBGRT

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

## Summary

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.

## Usage

**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.

### Secure Boot instructions

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](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](shim-signed/COPYRIGHT).

### Windows installation

* 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](shim.md).
	* Check the common [troubleshooting](#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.

### Quiet (batch) installation

* 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.

### Multi-boot configurations

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.

## Configuration

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

## Images

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.

## Troubleshooting

### Verification failed, Security violation

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

### Boot is slow, boot is stuck, just spinning

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.

### Image is not visible

Try to remove HackBGRT and install it first with the default config and image.
Some people report that installing another time (without first uninstalling) may also help.
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, run the setup again and select the option to check the boot log.
If the boot log is empty, then HackBGRT is not properly installed or you haven't properly rebooted.
If the boot log has contents but you didn't see the logo, there is some other problem.
You may report an issue and attach the `setup.log` file.

### Impossible to boot at all

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.

## Building

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