[maemo-developers] Can't debug an application under FREMANTLE_ARMEL target in Scratchbox

[From: Riku Voipio]

ext Burka Victor wrote:
> [sbox-FREMANTLE_ARMEL: ~/Projects/simple] > gdb simple
> GNU gdb 6.8
> Copyright (C) 2008 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "--host=i686-pc-linux-gnu --target=arm-none-linux-gnueabi"...
> (gdb) break main.cpp:6
> Breakpoint 1 at 0x885c: file main.cpp, line 6.
> (gdb) run
> Starting program: /home/victor/Projects/simple/simple
> Don't know how to run.  Try "help target".
> (gdb)

cross-gdb doesn't know howto run code. It is basically a tool to look at
coredumps.

> 
> 3.2.
> 
> [sbox-FREMANTLE_ARMEL: ~/Projects/simple] > native-gdb simple
> GNU gdb (GDB) 6.8.50.20090417-debian
> Copyright (C) 2009 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "arm-linux-gnueabi".
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>...
> (gdb) break main.cpp:6
> Breakpoint 1 at 0x885c: file main.cpp, line 6.
> (gdb) run
> Starting program: /home/victor/Projects/simple/simple
> qemu: Unsupported syscall: 26

qemu doesn't support ptrace syscall. gdb is basicly a glorified ptrace
wrapper. adding ptrace support to qemu would require quite a bit of
work.

> If anybody knows how to solve that problem, I would appreciate that.

Apart from from implementing ptrace in qemu, there little once can do
(currently). The closest one can do is abort(); at some point and the
use gdb to examine the coredump.