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On Tue, Aug 2, 2011 at 1:31 PM, Jonas Maebe <jonas.maebe@elis.ugent.be> wrote: > > On 02 Aug 2011, at 21:19, Ben L. Titzer wrote: > >> On Tue, Aug 2, 2011 at 12:00 PM, Jeffrey Walton <noloader@gmail.com> wrote: >>> Are you certain you are setting a breakpoint on an address (eg, b >>> 0x40000000)? Or is it a symbolic name (b main)? > > Just to make sure: to put a breakpoint on an address, it's "b *0x40000000" (i.e., with an extra "*"; but you'd notice if you used the wrong syntax, since gdb would complain that it can't find a symbol with that name). Yes, I am using the correct syntax and gdb will list the breakpoints I have added. > >> It's an address. I ænow for sure it's being executed because it's the >> first instruction in the binary. > > Actually, I've noticed on many platforms that breakpoints on the very first instruction don't work. Did you also try other instructions? > Doesn't matter, no breakpoints work. I've attached a sample binary and gdb session. ------------------- % gdb /tmp/add01 GNU gdb 6.3.50-20050815 (Apple version gdb-1515) (Sat Jan 15 08:33:48 UTC 2011) 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 "x86_64-apple-darwin"... (gdb) break *0x1114 Breakpoint 1 at 0x1114 (gdb) run Starting program: /private/tmp/add01 Program exited with code 04. (gdb) disass 0x1114 0x1140 Dump of assembler code from 0x1114 to 0x1140: 0x00001114: mov (%esp),%ebx 0x00001117: mov $0x0,%eax 0x0000111c: mov 0x1121(,%ebx,4),%edx 0x00001123: jmp 0x1129 0x00001125: add %al,(%eax) 0x00001127: add %al,(%eax) 0x00001129: call 0x1148 0x0000112e: push %eax 0x0000112f: mov %esp,%ebx 0x00001131: push $0x4 0x00001133: push %ebx 0x00001134: push $0x1 0x00001136: push $0x0 0x00001138: mov $0x4,%eax 0x0000113d: int $0x80 0x0000113f: push %eax End of assembler dump. (gdb) break 01148 No symbol table is loaded. Use the "file" command. (gdb) break *0x1148 Breakpoint 2 at 0x1148 (gdb) run Starting program: /private/tmp/add01 Program exited with code 04. (gdb) info breakpoints Num Type Disp Enb Address What 1 breakpoint keep y 0x00001114 2 breakpoint keep y 0x00001148 (gdb)
Attachment:
add01
Description: Binary data
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