Re: Watchpoints broken for 64-bit apps?
Re: Watchpoints broken for 64-bit apps?
- Subject: Re: Watchpoints broken for 64-bit apps?
- From: Jim Ingham <email@hidden>
- Date: Thu, 14 May 2009 11:52:05 -0700
Josh,
Watchpoint support for 64-bit Intel has worked since Xcode 2.4.1.
One caveat is that on Leopard, watchpoints must be set on each thread
individually. gdb does this on all the threads it sees every time it
stops, but since there's no "thread creation" event from the system,
we can't set the watchpoint on threads that are created while the
program is running. If the modification is happening from such a
thread, we won't catch it.
You can work around this on Leopard by putting a breakpoint on your
thread worker functions - you just set it to "continue", it doesn't
need to return control to the user for us to notice the new thread.
This problem was fixed in SnowLeopard.
Other than that I don't know of any cases where Intel 64 bit
watchpoints don't work. If you have a reproducible case please file a
bug. It's best if you can reduce the testcase to something manageable
that you can make available to us, but even if that's not possible, we
have some diagnostics we can turn on. Also be sure to tell us which
version of the Developer Tools you were using.
Jim
On May 14, 2009, at 8:52 AM, Josh Cameron wrote:
Hi,
I am debugging a 64-bit Intel app in Xcode/gdb. Memory is being
stomped, so
I am trying to set a watchpoint. It appears the watchpoint is set
successfully, but it is never hit, even though the data does change
in the
memory location being watched.
In a 32-bit test app, a watchpoint works properly, but in a 64-bit
version
of the same test app, the watchpoint has no effect.
Is this a known problem? Are watchpoints simply broken for 64-bit
Intel
apps? Is there something I'm missing?
____________
Josh Cameron
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