If I try to set a watchpoint I get a gdb error:
" can't clear hardware watchpoints without the 'Z2' (write-watchpoint) packet "
Then it seems to corrupt the device (on restarting the device it complains that the OS is too old for the SDK, even though it's OS 3.1.2).
I've got a bug to track down that really would be easy to track down with a watchpoint so this really is a pain.
Anybody know if watchpoints are supposed to work? How to get them to work?
Unfortunately this is a known bug in OS 3.1.2. There's rumour of a new 3.1.3 build around the corner, but I don't know if that will fix this problem.
I realize this is a very old post however I just got this same error message trying to set a watchpoint with XCode V4.3.2 (4E2002) running on OS X 10.7.3 Lion. I found the following link which explained that the message "can't clear hardware watchpoints without the 'Z2' (write-watchpoint) packet " indicates that the target machine doesn't have the needed hardware support. For me what this meant was that I needed to run under the iPhone Simulator instead of directly on iPhone 4. Also be aware that the latest version of XCode 4.3.2 defaults to (LLDB) debugger which in the XCode version does not support setting watchpoints. You must set debugger to GDB in menu Product:Edit Scheme. In the scheme edit dialog set the Debugger field pulldown to GDB.
来源：https://stackoverflow.com/questions/1598444/iphone-xcode-3-1-4-3-1-2-sdk-watchpoints-dont-work