gdb-6.3.0.0-1.131.EL4
        
1. Compile a test program on a 32-bit RHEL3, with gcc 2.96
$ cat test.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char ** argv)
{
        float f = 4.5;
        printf("%f\n", f);
        return 0;
}
$ gcc296 -g -o test test.c
        
2. Copy the binary to a RHEL4 x86-64 machine
3. Run in gdb:
$ gdb ./test
(gdb) b 8
Breakpoint 1 at 0x8048429: file test.c, line 8.
(gdb) run
Starting program: /home/bnocera/test
Reading symbols from shared object read from target memory...done.
Loaded system supplied DSO at 0xffffe000
        
Breakpoint 1, main (argc=1, argv=0xffffd8a4) at test.c:8
8       }
(gdb) p f
Cannot access memory at address 0xffffd814
        
On RHEL3 x86, and RHEL4 x86, "f" shows up properly:
(gdb) p f
$1 = 4.5