Re: mips64 elf64 problems

[Daniel Jacobowitz <drow at mvista dot com>]

On Fri, Nov 30, 2001 at 11:31:08AM -0800, Paul Mundt wrote:
> I was in the process of testing out kgdb with a mips64 target (using gdb 5.1),
> and ran into a rather peculiar problem. I have two images.. the vmlinux.64 is
> the one that is being booted on the target:
> 
> vmlinux:    ELF 32-bit MSB executable, mips-4 MIPS R3000_BE, version 1,
> statically linked, not stripped
> vmlinux.64: ELF 64-bit MSB executable, mips-4 MIPS R3000_BE, version 1,
> statically linked, not stripped
> 
> Upon trying to load these with gdb, the elf32 works just fine.. whereas the
> elf64 complains about not being able to read ECOFF debugging information:
> 
> lethal@freya:~$ mips64-linux-gdb vmlinux
> GNU gdb 5.1
> Copyright 2001 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 "--host=i686-pc-linux-gnu --target=mips64-linux"...
> (gdb)
> 
> lethal@freya:~$ mips64-linux-gdb vmlinux.64
> GNU gdb 5.1
> Copyright 2001 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 "--host=i686-pc-linux-gnu
> --target=mips64-linux"...Error reading ECOFF debugging information: File
> truncated
> 
> (gdb)
> 
> The kernels were both compiled with CONFIG_REMOTE_DEBUG turned on, so they
> were both compiled with -g.
> 
> I've tried this with a --target of mips64-linux as well as mips64-linux-elf,
> and the same thing happens both times.
> 
> Anyone have any insight on this?

What binutils version are you using to assemble (i.e. do you have
ECOFF/mdebug information at all)?

You're probably trying to use stabs (or mdebug) on a 64-bit binary.  I
know stabs will whine; I don't know if I've ever tried mdebug.  You
might want to use -gdwarf-2 instead, except of course Dwarf-2 is broken
on MIPS this month.

You might want to breakpoint in _bfd_mips_elf_read_ecoff_info in
elf64-mips.c.  I see that there's only a 32-bit version of this, so if
any data structures change on 64-bit you'll lose.

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer