Re: nm.h, *-nat.c and multi-arch?

[Andrew Cagney <ac131313@cygnus.com>]

> Date: Wed, 04 Jul 2001 12:11:58 -0400
>> From: Andrew Cagney <ac131313@cygnus.com>
>> 
>> o	customize to enable
>> extra (OS/arch specific?) features.
>> (The i386 hw breakpoint code
>> comes to mind.)
>> 
>> Here again, I think this should really
>> be host independant.
> 
> 
> I don't think it's possible, based on many hours of staring at the
> various implementations of hw breakpoints.  The differences are not
> always major, but IMHO significant enough to render any attempt to
> unify them be a huge effort with a very small benefit.
> 
> Even IA64 is sufficiently different from IA32 so as to prevent any
> reasonable attempt to unify the code which handles watchpoints.


I suspect I misspook.  I wouldn't expect some sort of unification of 
hardware breakpoints between different architectures (ia 32 vs ia 64). 
I was thinking more of better unification within an architecture.

For instance, a hardware breakpoint mechanism implemented purely as 
register reads/writes shouldn't need to do anything like access ptrace() 
directly.  Instead it should just access the target layer below it which 
(hopefully) is making available all the registers it needs.

A hardware breakpoint mechanism that required magic system calls, on the 
other hand, should be part of NAT.

	Andrew