Cobham Gaisler AB provides IP cores and supporting development tools for embedded processors based on the SPARC architecture. We specialize in digital hardware design for both commercial and aerospace applications


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 device and the future ESA Next Generation Microprocessor (NGMP).

Basic features

GRMON2 supports all features supported by GRMON:

  • 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 

GRMON2 also support a wide range of improvements and additions such as:

  • 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
  • A new help system, all commands are documented
  • Multi-core system support improvements
  • Batch scripts take arguments
  • Improved TAB-completion
  • Improved backtrace
  • Improved virtual memory handling
  • Improved and faster establishment of connection through debug interface
  • Improved processor/system frequency detection accuracy through debug interface
  • 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
  • Internal design improvement for future support, such as GUI


GRMON2 does currently not support a GUI.

Please refer to GRMON for support of the above. 

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.

Example of how Tcl can be used for debugging

The GRMON2 Tcl-scripting capability can be used to support advanced debugging routines. In the example below a Tcl-script is used to profile interrupt latency in a LEON3 system analysing the built-in AMBA AHB trace buffer content which is written to a file from which a graphical representation is created using a standard spread-sheet tool.

Tcl example

 Figure: Tcl source code

GRMON2 console

Figure: GRMON2 console output

Graphics generated from GRMON2 output

Figure: Graphics generated from GRMON2 output