[OpenBIOS] ppc(64) debugging (was: Q: How to "squeeze" C functions in between two symbols?)

Andreas Färber andreas.faerber at web.de
Mon Nov 1 00:33:21 CET 2010

Am 08.10.2010 um 15:30 schrieb Alexander Graf:

> You can use the apple gdb without an object file, so you don't get  
> symbols. But if you have an instruction pointer, just
>  $ qemu-system-ppc -s -S ...
>  (gdb) target remote localhost:1234
>  (gdb) b *0x1234 <- address of rtas_something
>  (gdb) c
> It should break on that IP and then you can evaluate the register  
> contents at least. Either by
>  (gdb) info registers
> or
>  (qemu) info registers

I'm trying to find out how far we get with the ppc64 OpenBIOS, so I've  
tried the following:

$ .../ppc64-softmmu/qemu-system-ppc64 ... -nographic -prom-env 'auto- 
boot?=false' -s -S

$ gdb --arch=ppc64
GNU gdb 6.3.50-20050815 (Apple version gdb-967) (Tue Jul 14 02:15:14  
UTC 2009)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and  
you are
welcome to change it and/or distribute copies of it under certain  
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for  
This GDB was configured as "powerpc-apple-darwin".
(gdb) target remote localhost:1234
Remote debugging using localhost:1234
[New thread 1]
0x0000000000000000 in ?? ()
(gdb) b *0xfffffffc
Breakpoint 1 at 0xfffffffc
(gdb) c

It doesn't break though and executes to the OpenBIOS prompt.
0xfffffffc is supposed to be the hard reset vector, i.e. the very  
first instruction it must execute to branch to _entry.

Any suggestions?


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