From mboxrd@z Thu Jan 1 00:00:00 1970 From: jtc@redback.com (J.T. Conklin) To: Todd Whitesel Cc: ac131313@cygnus.com (Andrew Cagney), gdb@sourceware.cygnus.com Subject: Re: SOFTWARE_SINGLE_STEP_P and multi-arch Date: Wed, 21 Mar 2001 15:59:00 -0000 Message-id: <5mae6eu17u.fsf@jtc.redback.com> References: <200103210951.BAA06932@shell17.ba.best.com> X-SW-Source: 2001-03/msg00235.html >>>>> "Todd" == Todd Whitesel writes: Todd> Cleaning out my mailbox I discovered something from early December: >> Hardware single step support (implied by >> !TARGET_SOFTWARE_SINGLE_STEP_P()) is target and not ISA/ABI >> dependant. >> >> Some ISAs might support hardware single step but the actual target >> may not (lousy OS support, limited stub functionality) Todd> I should also note that some ISAs might NOT support hardware Todd> single step but the actual target DOES, because it is simulated Todd> in software by the OS or stub. Indeed. I think some of our existing targets assume "hardware" single stepping when the ISA does not support it. So far, we have been lucky that all the ROM monitors, ICEs, and remote stubs emulate single step on those targets. At least as far as the remote protocol is concerned, a debug agent SHOULD support the single step command. If I could be assured that it wouldn't break anything, I'd change that to a MUST. The latency of having GDB do software single step makes debugging unpleasant. Todd> All modern VxWorks targets support this, and step-range as well. Todd> I expect that JTC's remote-wdb.c backend is using them. Indeed it does. --jtc -- J.T. Conklin RedBack Networks