gdb on Mac OS bpt implementation question

[Tristan Gingold]

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.

Tristan.