Exercise \- Feature Customization - Boot Order


In this exercise, we’ll learn how to change boot order from source code.

You can execute SBL with the following steps:

  1. Check current boot order in QEMU:

  • Look through the boot log on Command Prompt and locate string Getting boot image from... to determine the 1st boot device:

    python BuildLoader.py build qemu
Compile completed
  1. Modify board specific library,

  • in file <sbl_tree>\Platform\QemuBoardPkg\Library\Stage2BoardInitLib\Stage2BoardInitLib.c

  • In function UpdateOsBootMediumInfo ()

  • Add following at the end of the function to override the boot order:

    OsBootOptionList->CurrentBoot = 2;
Compile completed

  1. Rebuild SBL by using the following command:

    python BuildLoader.py build qemu
  2. Completion: you will see Done [qemu] on the screen after compile completed

  3. Execute SBL on QEMU by using the following command:

  • Windows:

    "C:\Program Files\qemu\qemu-system-x86_64.exe" -m 256M -machine q35 -serial stdio -pflash Outputs\qemu\SlimBootloader.bin -drive id=mydisk,if=none,file=..\Misc\QemuImg\QemuSata.img,format=raw -device ide-hd,drive=mydisk -boot order=d
  • Linux:

    qemu-system-x86_64 -m 256M -machine q35 -serial mon:stdio -nographic -pflash Outputs/qemu/SlimBootloader.bin -drive id=mydisk,if=none,file=../Misc/QemuImg/QemuSata.img,format=raw -device ide-hd,drive=mydisk -boot order=d
  1. Check the console Window to see the difference

Compile completed


Board customization can be done through board specific libraries, such as <sbl_tree>\Stage1ABoardInit/Stage1BBoardInit/Stage2BoardInit