64 bit convenience variables?

64 bit convenience variables?

[Shaheed]

Hi,

I've recently been working on 64 bit images, and noticed that several of my 
GDB scripts malfunctioned because the convenience variables cannot store a 64 
bit value (in my case, these are usually pointers). Thus:

shahhaqu@shahhaqu-w500:~$ file `which gdb`
/usr/bin/gdb: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically 
linked (uses shared libs), for GNU/Linux 2.6.15, stripped

shahhaqu@shahhaqu-w500:~$ gdb
GNU gdb (Ubuntu/Linaro 7.3-0ubuntu2) 7.3-2011.08
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://bugs.launchpad.net/gdb-linaro/>.
(gdb) set $foo=(void *)0x8000800080008000
warning: value truncated
(gdb) p/x $foo
$1 = 0x80008000

Is there any possibility that the width could be increased?

Thanks, Shaheed

Re: 64 bit convenience variables?

[Jan Kratochvil]

On Thu, 13 Oct 2011 23:21:17 +0200, Shaheed wrote:
> shahhaqu@shahhaqu-w500:~$ gdb
[...]
> This GDB was configured as "x86_64-linux-gnu".
[...]
> (gdb) set $foo=(void *)0x8000800080008000
> warning: value truncated

If you type:
(gdb) show architecture 
The target architecture is set automatically (currently i386)

This is because you have no file loaded to set GDB architecture according to
it.  You can set it manually:
(gdb) set architecture i386:x86-64

GDB can support many architectures although I agree it is more a bug the
primary target is not the default.


Regards,
Jan