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Re: gdb on Mac OS bpt implementation question
- From: Jason Molenda <jmolenda at apple dot com>
- To: Mick Jordan <mick dot jordan at oracle dot com>
- Cc: gdb at sourceware dot org
- Date: Thu, 10 Nov 2011 14:18:44 -0800
- Subject: Re: gdb on Mac OS bpt implementation question
- References: <4EB9BE43.7050200@oracle.com>
On Nov 8, 2011, at 3:41 PM, Mick Jordan wrote:
> I'd be grateful if someone could point me to where in the gdb source code that Mac OS specific breakpoint setting is done. The problem I am trying to resolve is how breakpoints are set in shared libraries, given that they are loaded read-only on Mac OS X (assuming the "write a bpt instruction" approach).
For what it's worth, two other implementations that may be worth consulting on issues like this are the Apple fork of gdb, downloadable here
http://opensource.apple.com/
although it's based on the gdb sources circa 2006-2007.
lldb, the new debugger that we've been writing recently is licensed under the LLVM copyright (berkeley-style) and has a public svn repository, is also a good reference for how debuggers work on the Mac OS X platform. v.
http://lldb.llvm.org/
although note that lldb's primary method of operation on Mac OS X is to debug the inferior via a gdbserver-like program via gdb remote protocol (our implementation is "debugserver" and the sources are in lldb/tools/debugserver in the source checkout). Originally we had lldb controlling the inferior process directly but on Mac OS X we've moved away from that and have all process done by debugserver - that's where you'd want to look to see how the low level memory reading/writing/etc is done.
Jason