Re: AW: [Simulavr-devel] [patch #3453] gdbserver.c gdb_extract_hex_nu m(...) bug fix (for more recent gdb versions)

[Paul Schlie]

In reality it makes no sense for any communications protocol to be dependant
on any machine's endian-ness, it should have a canonical form; where most
have choosen this to be big-endian, as then serialized values are send/read
as they would be spoken, most significant digit first left=>right, etc.

(but don't know what gdb's link protocol history was)

-paul-

> From: "Theodore A. Roth" <address@hidden>
> Date: Tue, 19 Oct 2004 18:01:07 -0700 (PDT)
> To: Paul Schlie <address@hidden>
> Cc: <address@hidden>
> Subject: Re: AW: [Simulavr-devel] [patch #3453] gdbserver.c gdb_extract_hex_nu
> m(...) bug fix (for more recent gdb versions)
> 
> On Tue, 19 Oct 2004, Paul Schlie wrote:
> 
>> Fully agree something's odd...
>> 
>> [fusion:~] paul% avr-gdb --version
>> GNU gdb 6.2.50_20041016
>> 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 "--host=powerpc-apple-darwin7.5.0 --target=avr".
>> 
>> (if gdb just branched, that would explain the 6.2/6.3 diff, I believe)
> 
> It's a bug in gdb. The 'p' packet was implemented recently (which
> explains why the bug in simulavr's gdbserver.c never got tickled):
> 
>   
> http://sources.redhat.com/cgi-bin/cvsweb.cgi/src/gdb/remote.c.diff?r1=1.147&r2
> =1.148&cvsroot=src
> 
> You are running on a big-endian system, I'm on a little-endian, thus the
> divergence.
> 
> The bug in gdb is in fetch_register_using_p(). In particular, this line:
> 
>   bin2hex((char *) &regnum, &buf[1], sizeof(regnum));
> 
> No attempt has been made to handle endian issues when converting the
> value of regnum from binary to a hex string.
> 
> ---
> Ted Roth
> PGP Key ID: 0x18F846E9
> Jabber ID: address@hidden