Use Case: Breaking at a Specific UEFI Module

  1. To load source information, boot till the EFI shell or idle loop and use the UEFI Scripted Buttons.
  2. To set a breakpoint in a module, choose one of the following options.
    • Option 1: Break at the module entry point
      1. In the menu bar, select: View > Source Files
      2. Right-click your desired module
      3. Select Create Breakpoint at Init

    • Option 2: Break at specific module's function

      Use the SET BREAK AT command in the Console window, using the format : SET BREAK AT {ModuleName.efi}KnownFunction, for example:

      xdb> SET BREAK AT {DxeCore.efi}DxeMain

  3. To reset the target from the debugger, select Run > Reset Target Default from the menu bar and wait for the target system to complete the reset. The debugger will halt the target at the reset vector (usually 0xF000:0xFFF0).
  4. Click the Run button in the debugger's toolbar.

    The target resumes execution. After a few seconds, the debugger hits the breakpoint, and the target is halted at the beginning of the desired function.


SW breakpoints do not persist over a reset, because during shadowing phase the module is reloaded to memory and it will overwrite the SW breakpoint. HW breakpoints will persist but the module could be loaded to a different address and the HW breakpoint location is altered after a reset.

The debugger can run to a UEFI module by the module name if the agent based connection over a serial cable is used. See Setting Up the Target about how to set up the agent-based connection.

For more complete information about compiler optimizations, see our Optimization Notice.