Compile gdbserver for powerpc

...

Whoops. This should probably change. I use gdb for kernel debugging on the (8xx) 2.[34].x kernels (its *very* handy!). You need to enable CONFIG_KGDB first though, and if you don't want to use the default serial port (via SMC1?? for 8xx) you need to do a bit of hacking. Here's how:

1. make sure either CONFIG_SERIAL_CONSOLE, or CONFIG_KGDB, itself is undefined when 8xx_io/uart.c is compiled

2. ensure the call to kgdb_map_scc() is not done in arch/ppc/kernel/setup.c; replace it with a call to your own serial port init routine, if required.

3. write three functions (usually in your serial driver, and inside #ifdef CONFIG_SERIAL_CONSOLE, inside #ifdef CONFIG_KGDB):

	extern void putDebugChar(char kgdb_char);
	extern char getDebugChar(void);
	extern void kgdb_interruptible(int yes);

the first two are fairly obvious - busy-wait put and get character to the chosen serial port. the third enables (yes==1) or disables (yes==0) *serial* interrupts (not all interrupts - at least I don't think so).

e.g. #ifdef CONFIG_SERIAL_CONSOLE

	... (serial console stuff) ...
	#ifdef CONFIG_KGDB
	void
	putDebugChar(char c)
	{
	...
	#endif /* CONFIG_KGDB */
	#endif /* CONFIG_SERIAL_CONSOLE */

1 and 2 are for the 8xx kernel - there will be similar steps for other platforms (i.e. making sure the code for the default kgdb serial "driver" is not compiled in, obviously so there is not a clash with the ones you write).

One thing to remember: if you enable CONFIG_KGDB, setup_arch() in arch/ppc/kernel/setup.c will execute a breakpoint() and for the kernel to proceed past that point, you must start gdb on your host in "remote" mode (on the appropriate serial port with the appropriate speed) and perform a gdb "continue" command (this caused me some concern when it was added a few months ago, I thought my kernel was dead :-)

Hope this helps. Cheers!

								Murray...

--
Murray Jensen, CSIRO Manufacturing Sci & Tech, Phone: +61 3 9662 7763
Locked Bag No. 9, Preston, Vic, 3072, Australia. Fax: +61 3 9662 7853
Internet: [email protected] (old address was [email protected])

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

...

It already had. Lucinda must be looking at an old copy of the HOWTO.

Regards,
Graham
--
Graham Stoney
Principal Hardware/Software Engineer
Canon Information Systems Research Australia
Ph: +61 2 9805 2909 Fax: +61 2 9805 2929

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/