Back to Results

Patent Title: Method for using two copies of open firmware for self debug capability

Assignee: IBM
Patent Number: US6219828
Issue Date: 04-17-2001
Application Number:
File Date:09-30-1998

Abstract: A first copy of Open Firmware is loaded into system memory to supply a debug function and a second copy of the same firmware is then loaded to provide functional code which is to be debugged. The first copy of Open Firmware in system memory is designated as the resident debugging function. Kernel code, within the first copy, sets up an executing environment for the debugger, such as system exception handlers and debug console enablement. Normal Open Firmware configuration variables are retrieved from Non-Volatile Random Access Memory ("NVRAM") by the first copy and transmitted to the loader. The second copy of Open Firmware is loaded into system memory to a location specified by the configuration variables. The second copy firmware image is designated as a normal Open Firmware operation in the system. The second copy initially takes over all system exception handlers except instruction breakpoint exception, program interrupt exception and trace exception. The instruction breakpoint exception is utilized to invoke the first copy, or resident debugger, from the normal Open Firmware (second copy) image during code debugging. The two copy debugging configuration is utilized in conjunction with an online machine language assembler and disassembler.

Notes:

Link to USPTO

IBM Pledge dated 1/11/2005