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

[Andreas Färber]

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  
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for  
details.
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
Continuing.

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?

Andreas