This is the mail archive of the gdb@sourceware.cygnus.com mailing list for the GDB project. See the GDB home page for more information.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]

Re: Any way to avoid inserting & removing breakpoints?

> jtc@RedBackNetworks.com (J.T. Conklin) writes:
> > I finished my breakpoint extensions prototype, and discovered that GDB
> > inserts all enabled breakpoints when program execution is resumed, and
> > removes them when it regains control.  
> 
> Yes, this is a "feature".  It's pretty well wired into GDB.  It might
> be possible to make insert_breakpoints() and remove_breakpoints() do
> some sort of caching-like thing, but I'm not sure that all target
> memory reads know about substituting original code, so you might get
> punished when you're doing disassembly or prologue analysis.

You're right, target memory reads don't know about substituting the
original code.  I got around that problem by having my stub restore
memory before control is returned to GDB and to (re-)insert break-
points just before program execution resumes.

I haven't investigated, but it's conceivable that some ROM monitors do
the same thing (for much the same reasons --- simplifying internal
disassembly).  If GDB was extended to avoid inserting and removing
breakpoints, it could only be used on targets that manage breakpoints
in this manner.

	--jtc

-- 
J.T. Conklin
RedBack Networks