[Openocd-development] cortex breakpoint trouble, R546

[Edwin O. <eo...@mi...>]

Hi,

I have a Luminary L3S6965 evaluation board with a cortex core in it. 
Most debugging operations via an olimex arm-usb-ocd  seem to work quite 
well, but one thing that does not work is evaluating expressions 
containing function calls from gdb.

I.e., imagine a trivial function led(int v) that turns on/off an LED. 
I'm typing:

(gdb) p led(1)

The command fails, with the following output:

Warning:
Cannot insert breakpoint 0.
Error accessing memory address 0x0: Unknown error 4294967295.

Openocd's debug output is:

Debug:   370 698316 gdb_server.c:1815 gdb_input_inner(): received 
packet: 'Pe=00000000'
Debug:   371 698316 gdb_server.c:959 gdb_set_register_packet(): -
Debug:   372 698316 gdb_server.c:1815 gdb_input_inner(): received 
packet: 'Pd=d8010020'
Debug:   373 698316 gdb_server.c:959 gdb_set_register_packet(): -
Debug:   374 698316 gdb_server.c:1815 gdb_input_inner(): received 
packet: 'Pf=90010000'
Debug:   375 698316 gdb_server.c:959 gdb_set_register_packet(): -
Debug:   376 698316 gdb_server.c:1815 gdb_input_inner(): received 
packet: 'P19=20000061'
Debug:   377 698316 gdb_server.c:959 gdb_set_register_packet(): -
Debug:   378 698317 gdb_server.c:1815 gdb_input_inner(): received 
packet: 'Z0,0,4'
Debug:   379 698317 gdb_server.c:1253 gdb_breakpoint_watchpoint_packet(): -
Info:    380 698317 cortex_m3.c:914 cortex_m3_add_breakpoint(): only 
breakpoints of two bytes length supported
Info:    381 698317 breakpoints.c:73 breakpoint_add(): can't add 
hardware breakpoint, resource not available
Error:   382 698317 gdb_server.c:1022 gdb_error(): unexpected error -308
Debug:   383 698317 gdb_server.c:1815 gdb_input_inner(): received 
packet: 'Pd=e0010020'
Debug:   384 698317 gdb_server.c:959 gdb_set_register_packet(): -
Debug:   385 698317 gdb_server.c:1815 gdb_input_inner(): received 
packet: 'Pe=ffffffff'
Debug:   386 698317 gdb_server.c:959 gdb_set_register_packet(): -
Debug:   387 698317 gdb_server.c:1815 gdb_input_inner(): received 
packet: 'Pf=3f010000'
Debug:   388 698317 gdb_server.c:959 gdb_set_register_packet(): -
Debug:   389 698317 gdb_server.c:1815 gdb_input_inner(): received 
packet: 'P19=00000061'
Debug:   390 698317 gdb_server.c:959 gdb_set_register_packet(): -

It seems that a four-byte length breakpoint is requested, but only two 
byte breakpoints are supported by the cortex target. Any suggestions?

-Ed