After reading the handbook and some postings in the mailing list archive.
I still can not make remote debugging work. I basically did the following
on FreeBSD-current 4.0 (A is debugging machine, B is the target):
(1) Build a debug kernel (options DDB and BREAK_TO_DEBUGGER) on box A.
The sio flag I used is 0x90 (I also tried 0x80). Ftp the file /kernel to
box B and renamed as /kernel.A
(2) Boot the kernel /kernel.A on box B with -d option:
>>FreeBSD/i386 boot
Default: 0:wd(0,a)/boot/loader
boot: /kernel.A -d
Debugger("Boot flags requested debugger")
Stopped at 0xc0252c27: movl $0, 0xc031ed98
db> gdb
Next trap will enter GDB remote protocol mode
db> s
(3) On machine A, go to the compile directory:
#gdb -g kernel.debug
(kgdb) target remote /dev/cuaa0
Remote debugging using /dev/cuaa0
Ignoring packet error, continuing...
Ignoring packet error, continuing...
Couldn't establish connection to remote target
Malformed response to offset query, timeout
The serial cable is null-modem and has been tested with kermit. It is
connected to /dev/ttyd0 (com 1) of machine B and com 2 of machine A.
I did not do "strip -x" because I assume this is done by FreeBSD 4.0
automatically and the file debug.kernel is the one with symbols.
Any help is appreciated.
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Zhihui Zhang. Please visit http://www.freebsd.org
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