[openrisc] gdb over jtag requirements?

[Andreas Rasmusson <ara@voxi.se>]

Hi

I'm trying to run gdb over the jtag interface on an
openrisc but have run into some difficulties.

Loading a program into ram and starting it via gdb
works fine. However, it does not respond to when i
press ctrl-C in gdb or if i set breakpoints.

Does debugging over gdb require anying particular from
the system that is beeing debugged, e.g that certain
interrupts are enabled? Something else?

The processor i run on is configured to have rom from
adresses 0x0 to 0x1000000 so i cannot set interrupthandlers
by way of the program that i load.


Another thing, when i start the jtag-proxy 'jp1-xilinx' it
prints some messages , e.g
 
 Read      npc = 08020014 ppc = 08020010 r1 = fffffffb
 Expected  npc = 4000000c ppc = 40000024 r1 = 00000005
 Read      npc = 00000e00 ppc = 00000e00 r1 = fffffffe
 Expected  npc = 4000000c ppc = 40000024 r1 = 00000008
 Read      npc = 00000e00 ppc = 00000e04 r1 = 00000001
 Expected  npc = 40000024 ppc = 40000020 r1 = 0000000b

What are these? Should I be concerned that the read values
differ from the Expected values?

Any hints would be appreciated.

/Andreas Rasmusson, Voxi


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