how are debug registers supposed to work?

[Andrew Cagney]

> So, the CPU is generating a debug exception, and I am catching it.  it's
> just not happening when I want or expect it to happen.  The same thing
> happens for program instruction fetches.  It doesn't break.
> 
> I stuck in all the wbinvd instructions thinking it might be a cache
> issue.  I have yet to turn the cache off.  it seems to me though that I
> should be getting some exception with or without the cache enabled.
> 
> What am I doing wrong?  anyone know?  who knows how to use these
> registers?

Just a thought, you're not fighting a user space process playing with 
those registers?

The other is to look at GDB using hardware debug registers on a user 
process.

Andrew