Re: Save the length of inserted breakpoints

[Mark Kettenis <mark.kettenis@xs4all.nl>]

> Date: Thu, 2 Mar 2006 18:10:42 -0500
> From: Daniel Jacobowitz <drow@false.org>
> 
> On Fri, Mar 03, 2006 at 12:01:52AM +0100, Mark Kettenis wrote:
> > > Date: Thu, 2 Mar 2006 17:17:11 -0500
> > > From: Daniel Jacobowitz <drow@false.org>
> > > 
> > > This nasty, mechanical patch adds "len" arguments to
> > > target_remove_breakpoint and target_remove_hw_breakpoint.  The goal is
> > > to allow BREAKPOINT_FROM_PC to include heuristics, which may possibly
> > > change between when a breakpoint is inserted and when it is removed;
> > > in order to stay in sync, we need to always remove breakpoints in the
> > > same way that we inserted them.
> > > 
> > > There's not much more to say about this patch.  It's big, obvious, and
> > > pretty ugly.  Any comments on this?  Does it look OK?
> > 
> > Yuck!  It really is ugly.  For one thing, I think it is a bit
> > pointless, to add a the BREAKPOINT_FROM_PC() to targets where we know
> > the length of a breakpoint instruction is fixed.
> > 
> > Another thing is that I think the order of the arguments of
> > target_remove_breakpoint() is wrong.  I think it makes sense to see
> > your "len" argument as the length of the saved memory.  Then it is
> > more logical to make "len" the last argument of
> > target_remove_breakpoint().
> > 
> > However, doesn't it make more sense to have target_insert_breakpoint()
> > save the length instead of using BREAKPOINT_FROM_PC() to ask for it?
> 
> If you want me to do that, I'll do that instead.  It requires touching
> twice as many target functions.  Writing the changelog for this one
> took long enough, so forgive me if I wait a while before trying it
> again :-)

You're touching a fairly fundamental piece of the breakpoint
infrastructure here.  I think it is worth thinking about this for a
bit longer.  My comments certainly weren't "demands", so I'm perfectly
fine with discussing this a bit more before you rush towards changing
your patch ;-).

Mark