Albatron Technology ARM11/Cortex-A8

bdiGDB

for GNU Debugger, BDI2000 (ARM11/Cortex-A8) User Manual 40

3.3 Debugging with GDB

Because the target agent runs within BDI, no debug support has to be linked to your application.

There is also no need for any BDI speciﬁc changes in the application sources. Your application must

be fully linked because no dynamic loading is supported.

3.3.1 Target setup

Target initialization may be done at two places. First with the BDI conﬁguration ﬁle, second within the

application. The setup in the conﬁguration ﬁle must at least enable access to the target memory

where the application will be loaded. Disable the watchdog and setting the CPU clock rate should

also be done with the BDI conﬁguration ﬁle. Application speciﬁc initializations like setting the timer

rate are best located in the application startup sequence.

3.3.2 Connecting to the target

As soon as the target comes out of reset, BDI initializes it and loads your application code. If RUN is

selected, the application is immediately started, otherwise only the target PC is set. BDI now waits

for GDB request from the debugger running on the host.

After starting the debugger, it must be connected to the remote target. This can be done with the fol-

lowing command at the GDB prompt:

(gdb)target remote bdi2000:2001

bdi2000 This stands for an IP address. The HOST ﬁle must have an appropriate

entry. You may also use an IP address in the form xxx.xxx.xxx.xxx

2001 This is the TCP port used to communicate with the BDI

If not already suspended, this stops the execution of application code and the target CPU changes

to background debug mode.

Remember, every time the application is suspended, the target CPU is freezed. During this time no

hardware interrupts will be processed.

Note: For convenience, the GDB detach command triggers a target reset sequence in the BDI.

(gdb)...

(gdb)detach

... Wait until BDI has resetet the target and reloaded the image

(gdb)target remote bdi2000:2001

Note:

GDB sometimes fails to connect to the target after a reset because it tries to read an invalid stack

frame. With the following init list entries you can work around this GDB startup problem:

WGPR 11 0x00000020 ;set frame pointer to free RAM

WM32 0x00000020 0x00000028 ;dummy stack frame