x86 hardware breakpoint question

[Steven Bauer <bauer@atlas.lcs.mit.edu>]

Quick question, does gdb support hardware breakpoints on
x86 architectures?  I have been trying to get them to work keep
getting an unknown error. 

(gdb) hbreak   *0x80485d9    

....

warning: Cannot insert breakpoint 3:
Error accessing memory address 0x80485d9: Unknown error 4294967295.


One other question, is there any way to have breakpoints enabled
when an exec occurs.  What I would like to do is continue through the
exec getting the sigtrap if the new process is loaded, delete old
breakpoints, load the symbols for the new process, and eventually 
reset breakpoints once main is hit.  The reason I want this is that
the exec could fail, in which case I want the original breakpoints to
still be in place.  If I remove all the breakpoints before the 
exec, continue, and the exec fails, I miss all the functions I 
originally had breakpoints set for.

Thanks,
Steve