Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site rtp47.UUCP Path: utzoo!watmath!clyde!bonnie!akgua!mcnc!rti-sel!rtp47!smithrd From: smithrd@rtp47.UUCP (Randy D. Smith) Newsgroups: net.unix Subject: Re: how does adb/dbx work? Message-ID: <140@rtp47.UUCP> Date: Wed, 14-Aug-85 18:50:21 EDT Article-I.D.: rtp47.140 Posted: Wed Aug 14 18:50:21 1985 Date-Received: Sat, 17-Aug-85 16:33:08 EDT References: <410@uvm-cs.UUCP> Reply-To: smithrd@dgux.UUCP (Randy D. Smith) Organization: Data General, RTP, NC Lines: 16 Summary: dbx uses software simulation In article <410@uvm-cs.UUCP> hartley@uvm-cs.UUCP (Stephen J. Hartley) writes: >I was wondering if somebody could explain how adb (and dbx) executes programs. >Does it have a software simulator that interprets the instructions in the >object file of the program being debugged? Or does it use the VAX hardware >to execute the program, say by hardware single-stepping?... dbx uses software simulation. I recall finding code to use the hardware- trace-bit method, but it was never called from anywhere. Instead, dbx would determine where the next location would be based on the current machine state and the next instruction to be executed. I think some of the stuff was taken from adb verbatim, by the way, so I expect it behaves similarly. It sure made my day when I found the trace bit wasn't being used (the machine I ported it to had no trace bit). -- Randy D. Smith (919) 248-6136 Data General, Research Triangle Park, NC!mcnc!rti-sel!rtp47!smithrd