Re: [Patch] arch recognition fix for osabi.c

[Daniel Jacobowitz <drow@mvista.com>]

On Tue, Jun 17, 2003 at 12:04:32PM -0400, Kris Warkentin wrote:
> > This half I'm not convinced by.  From our previous exchange I don't
> > think you've fully justified it.  Not approved without more discussion.
> 
> Okay.  Let's use mips as an example.  The 'compatible' check returns true if
> they have the same arch (ie. bfd_arch_mips).  There will be many different
> values for the arch_info pointer, all with bfd_arch_mips and various other
> pieces of info such as which machine type (10k, 4300, etc.) of mips it is.
> The handler was registered for bfd_arch_mips with no other information.  In
> the absence of the ABILITY to do anything smarter, we have to assume that if
> the handler is for bfd_arch_mips, it should be run.
> 
> As it stands, if the bfd reads a file and says 'this is a tx3900' or some
> such, the pointers won't be the same and my backend init_abi won't be run
> even though I want it to run for all mips targets.

All calls to gdbarch_register_osabi in GDB except for two use mach ==
0.  The two are mips-linux-tdep.c, which appears to be solving the same
problem - what a coincidence:
  for (arch_info = bfd_lookup_arch (bfd_arch_mips, 0);
       arch_info != NULL;
       arch_info = arch_info->next)
    {
      gdbarch_register_osabi (bfd_arch_mips, arch_info->mach, GDB_OSABI_LINUX,
                              mips_linux_init_abi);
    }
and x86-64.  For x86-64 your change is correct since BFD will catch the
different bits-per-word and return NULL.  For mips-linux-tdep it would
let you remove that loop, which I have a vague memory of being annoyed
at when it became necessary.

The check came from

2002-12-14  Mark Kettenis  <kettenis@gnu.org>

        * osabi.c: Include "gdb_assert.h" and "gdb_string.h".
        (struct gdb_osabi_handler): Remove member `arch'.  Add member
        `arch_info'.
        (gdbarch_register_osabi): Add new argument `machine'.  Use ot to
        construct a `struct bfd_arch_info' and store it in the `struct
        gdb_osabi_handler' that is created.
        (gdbarch_init_osabi): Check for compatibility based on machine
        type and architecture.
        * osabi.h (gdbarch_register_osabi): Adjust prototype and update
        comment.

So I'm not going to approve it until Mark comments.  Mark, Kris is
suggesting that the "arch_info ==" in the ->compatible check should
simply be a "NULL !=".

> > >       (generic_elf_osabi_sniff_abi_tag_sections): Add check for QNX
> Neutrino
> > > binaries.
> >
> > This bit looks fine, except for two things: you've missed the coding
> > standards by four space characters (before left parens), and your
> > "safety first" check overruns the buffer (missing +1 in the alloca).
> 
> Doh!  Not very safe was it?  Sorry about that.  Fixed.
> 
> cheers,
> 
> Kris
> 
> 
> 

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer