GRMON2 is a debug monitor for the LEON2, LEON3 and LEON4 Debug Support Unit (DSU), providing a non-intrusive debug environment on real target hardware. The LEON DSU can be controlled through any AMBA AHB master and GRMON2 therefore supports communication through a large number of interfaces.

GRMON2 has extended support for multi-core systems, such as the dual-core GR712RC Dual-Core LEON3FT Processor and GR740 Quad-Core LEON4FT Processor devices..

Basic features

  • Read/write access to all LEON registers and memory
  • Downloading and execution of LEON applications
  • Built-in disassembler and trace buffer management
  • Breakpoint and watchpoint management
  • Command-line mode
  • Remote connection to GNU debugger (GDB)
  • Single word or burst access to AMBA on-chip bus
  • GRLIB Plug & Play support
  • Auto-probing and initialisation of LEON peripherals and memory settings
  • Error injection for fault-tolerant LEON processors
  • Supported debug interfaces: PCI, USB, Ethernet, JTAG, UART and SpaceWire
  • Common Flash Interface (CFI) compatible Flash PROM programming

Advanced features 

  • Tcl interactive interpreter support
    • All commands have been rewritten to support Tcl syntax
    • TAB-completion on Tcl variables, procedures, namespaces etc.
    • Tcl scripting:
      • GRMON2 commands leave return values for scripting
      • Variables are exported that let the user access DSU and debug drivers without using commands
      • Start-up scripts
    • Extend GRMON2:
      • custom AMBA cores using new Tcl-driver interface
      • easy custom command implementation using Tcl
      • install custom handlers (hooks) on certain events
  • In-application help system with full command reference
  • Multi-core system support
  • GDB does not consume the console, i.e. it's possible to inspect registers etc. while GDB is connected
  • GDB watchpoint support
  • Translates virtual addresses for GDB, e.g. it's possible to debug the Linux kernel
  • Expanded register information listing


GRMON2 provides a terminal based user interface. It is not a GUI application.

Supported platforms and system requirements

GRMON2 is currently provided for platforms: Linux-x86, Windows XP SP3 and Windows 7.

Documentation and download

GRMON2 user manual is available on-line.

Professional and evaluation versions of GRMON2 for Linux and Windows can be obtained from the download page.