BSP Developer's Guide

VxWorks 5.5
BSP Developer’s Guide
Caveats
Because the virtual I/O driver requires the kernel, add the following line to
config.h:
#undef INCLUDE_WDB_VIO
There is an important caveat if you are planning to use the target agent’s serial-line
communication path. When the kernel is first started, interrupts are enabled in the
processor, but driver interrupt handlers are not yet connected. You must take care
to ensure that the serial device you use for agent communication does not generate
an interrupt. If your board has an interrupt controller, use it to mask serial
interrupts in sysHwInit( ). Beware that the target agent tries to use all drivers in an
“interrupt on first packet” mode. As a result, you should modify the serial driver
to refuse to go into interrupt mode, even if the agent requests it.
System-Mode Debugging Techniques
After you have the agent working, you will want to use it to debug the VxWorks
image to which it is linked. To save download time, you should link the VxWorks
code you want to test into the ROM image. In particular, you should glance at
section 3.4 Using a Minimal Kernel, p.55 to see what driver code to link with
VxWorks. To avoid remaking ROMs, consider adding hooks to your BSP and
driver routines as follows:
void (*myHwInit2Hook)(void); /* declare a hook routine */
...
void sysHwInit2 (void)
{
if (myHwInit2Hook != NULL) /* and conditionally call it */
{
myHwInit2Hook();
return;
}
... /* default code */
}
This allows you to replace the routine from the debugger dynamically. For
example, to override the behavior of sysHwInit2( ) above, just create a new
version of it called myHwInit2( ) in a module called myLib.o, and then type:
(gdb) load myLib.o
(gdb) set myHwInit2Hook = myHwInit2
(gdb) break myHwInit2
(gdb) continue
However, if you start the agent before the kernel, you must start it after the call to
sysHwInit( ). Thus, you cannot override sysHwInit( ). On the other hand, you
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