gdb on Mac OS bpt implementation question

Tristan Gingold
Wed Nov 9 07:48:00 GMT 2011

On Nov 9, 2011, at 12:41 AM, 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). The context for this is a custom debugger we have for a Java VM (Maxine) which uses "write a bpt instruction" and works fine setting breakpoints in shared library code on Linux and Solaris, but not on MacOS (we get access faults trying to write the BPT instruction).

See darwin-nat.c:darwin_read_write_inferior.

If you want to write to a page, you have to make it writable.


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