How to get gdb working on Apple iOS 4.3.x

► Step 1: Download and install gdb

1) Download gdb at http://apt.saurik.com/debs/gdb_1518-11_iphoneos-arm.deb
2) Transfer the file to the iDevice (e.g. via SSH)
3) Install the package with the following command

iPhone:~ root# dpkg -i gdb_1518-11_iphoneos-arm.deb

This version of gdb will work on iOS 4.3.x with ASLR but it has a problem displaying the register values. To solve this issue I wrote a little gdb script.

► Step 2: Download and use my gdb script

1) Download the gdb script at http://www.trapkit.de/pub/registers.gdb
2) Transfer the file to the iDevice (e.g. via SSH)
3) Start gdb and load the script with the following command:

(gdb) source registers.gdb

The script implements a new gdb command called 'ir' ([i]nfo[r]egisters) that lists the registers and their contents. Example output:

(gdb) ir
r0      0x10004005      268451845
r1      0x07000006      117440518
r2      0x00000000      0
r3      0x00000c00      3072
r4      0x00001a03      6659
r5      0xffffffff      -1
r6      0x00000000      0
r7      0x2feb5dbc      803954108
r8      0x00000000      0
r9      0x3f45afb4      1061531572
r10     0x00000000      0
r11     0xffffffff      -1
sp      0x2feb5d84      803954052
lr      0x35cd575f      902649695
pc      0x35cd5c00      902650880

Alternatively, rename the file to '.gdbinit' and put it in the home directory of the user that will run gdb.