Re: How to configure gdb on arm-linux (for CDB89712)

[Dmytro Bablinyuk <dmytro dot bablinyuk at tait dot co dot nz>]

> > > On host:
> > >
> > > This GDB was configured as "--host=i686-pc-linux-gnu
> > > --target=arm-linux"...
> > > (gdb) target remote 172.25.193.23:1023
> > > Remote debugging using 172.25.193.23:1023
> > > 0x00008110 in _start ()
> > > (gdb) b main
> > > Breakpoint 1 at 0x8158: file hello.c, line 4.
> > > (gdb) c
> > > Continuing.
> > >
> > > Program received signal SIGILL, Illegal instruction.
> > > 0x00008114 in _start ()
> > > (gdb)
> > >
> > >
> > > On target(CDB89712)
> > >
> > > # gdbserver 172.25.140.19:1023 /armdevelop/hello
> > > Process /armdevelop/hello created; pid = 196
> > > Remote debugging from host 172.25.140.19
> > > hello(135): undefined instruction: pc=00008114
> > > Code: e91ba800 e3a0b000 (e7ffdefe) e1a0100d e0812100
> > > Killing inferior
> > > #
> >
> > This is a known problem between GDB 5.3 and uclibc: uclibc doesn't
> > leave the identifying marks that GDB uses to figure out that something
> > is a "Linux" binary rather than a "generic ELF" binary.  Try a CVS
> > snapshot of GDB and I bet it'll work.
>
> Thank you Daniel,
>
> I got a CVS snapshot and I have a little different result now.
> I tried to compile it the same way (arm-linux) and using 
> armv4l-unknown-linux option but in both cases result was the same 
> "Segmentation fault"
> Below I attached a debug output from gdb and gdbserver.
> May be I am doing something plainly wrong?
> Another interesting detail I noticed - in previous version I had 
> 0x00008110 in _start () in this version 0x40000d20 in ?? ().
I have discovered that if you try to continue wihout breakpoint it sends 
a messages:

(gdb) c
Continuing.
Sending packet: $Z0,8110,4#e0...Ack
Packet received:
Packet Z0 (software-breakpoint) is NOT supported
Sending packet: $m8110,4#97...Ack        
Packet received: 03000000
target_xfer_memory (0x8110, xxx, 4, read, xxx) = 4, bytes = 03 00 00 00
Sending packet: $X8110,0:#b8...Ack       
Packet received:
binary downloading NOT suppported by target
Sending packet: $M8110,4:fedeffe7#ad...Ack  << write mem at 0x8110, 4 
bytes, fedeffe7 - this fails on target!!
Packet received: OK
target_xfer_memory (0x8110, xxx, 4, write, xxx) = 4, bytes =
fe de ff e7
target_insert_breakpoint (0x8110, xxx) = 0
...

On target this looks like:

Jan  1 00:45:29 name user.debug klogd: hello: unhandled page fault at 
pc=0x40003148, lr=0xe7ffdefe (bad address=0x7ffe7118, code 0)

According to http://sources.redhat.com/ml/gdb/2002-08/msg00141.html

$M8110,4:fedeffe7 - "That's not an arm-linux breakpoint, it's an ARM 
breakpoint. That's why it isn't working."

I tried to play with set architecture and set osabi but without any luck.

Daniel, you were in that discussion 
(http://sources.redhat.com/ml/gdb/2002-08/msg00141.html) - is there any 
other ways to tell GDB to recognise uClibc binaries?