David Godfrey

Important changes to forums and questions

All forums and questions are now archived. To start a new conversation or read the latest updates go to forums.mbed.com.

10 years, 11 months ago.

Why and how should we "modify vector checksum value"?

When you run make on an exported (GCC ARM Embedded) "blinky" you get a message in the compile output saying

*****
***** You must modify vector checksum value in *.bin and *.hex files.
*****

/opt/gcc-arm/bin/arm-none-eabi-size GCC_Eclipse_Debug.elf
   text	   data	    bss	    dec	    hex	filename
  27512	    180	    764	  28456	   6f28	GCC_Eclipse_Debug.elf

It is not clear why or how to modify these values. Nor is a quick search turning anything up.

Question relating to:

Last updated: 30 Apr 2020

This is also reported by OpenOCD when you run GDB for debugging....

Info : JTAG tap: lpc17xx.cpu tap/device found: 0x4ba00477 (mfg: 0x23b, part: 0xba00, ver: 0x4)
target state: halted
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x1fff0080 msp: 0x10001ffc, semihosting
Warn : keep_alive() was not invoked in the 1000ms timelimit. GDB alive packet not sent! (1546). Workaround: increase "set remotetimeout" in GDB
Warn : Verification will fail since checksum in image (0x00000000) to be written to flash is different from calculated vector checksum (0xefff2f8e).
Warn : To remove this warning modify build tools on developer PC to inject correct LPC vector checksum.
Warn : keep_alive() was not invoked in the 1000ms timelimit. GDB alive packet not sent! (57899). Workaround: increase "set remotetimeout" in GDB
posted by David Godfrey 11 Mar 2015

1 Answer

Martin Kojtal
10 years, 11 months ago.

This one explains it, http://bgamari.github.io/posts/2012-03-28-jtag-over-buspirate.html, there's flashing new image section.

Not certain though, if this is still valid. I have never edit that vector checksum for the mbed board

posted by Martin Kojtal 11 Mar 2015

The checksum is usually inserted by the programmer/flash device. This is the case for the Segger JFlash and for the NXP Flashmagic utility. I guess that the mbed interface chip has a similar function. See here

posted by Wim Huiskamp 11 Mar 2015

Thanks wim. That's why I havent done it manually :)

posted by Martin Kojtal 11 Mar 2015

Thanks, much as I thought. It's just another piece of the puzzle for using Eclipse and OpenOCD.

Martin,keeping in mind that I hope to sort out GCC export with eclipse project files, if we were to provide a tool that an eclipse project file could call (ie: autogenerated project file included in the export) do you think it would be acceptable to provide a linux binary, and a windows binary as part of the export with the makefile calling whichever is appropriate? MAC OS may be possible as well, but I don't know for sure as I have no experience with mac's.

I just did a test compile of the code you linked to with linux 64bit gcc (no arguments) and got a 6280 byte binary. There are a few other options I can think of easily,

  • use some makefile magic to dump the needed 306 bytes of source to a temp file and compile before use. would require gcc to be available.
  • require user to download the tool and place it in the path. warn if it's not available
  • reimplement as bash/perl/python/etc this would work well on most linux systems, and likely OSX, but could be a pain for windows systems.
posted by David Godfrey 11 Mar 2015