From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4833 invoked by alias); 24 Mar 2005 20:37:54 -0000 Mailing-List: contact gdb-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sources.redhat.com Received: (qmail 4791 invoked from network); 24 Mar 2005 20:37:48 -0000 Received: from unknown (HELO nevyn.them.org) (66.93.172.17) by sourceware.org with SMTP; 24 Mar 2005 20:37:48 -0000 Received: from drow by nevyn.them.org with local (Exim 4.50 #1 (Debian)) id 1DEZ5q-00021S-Jq; Thu, 24 Mar 2005 15:38:14 -0500 Date: Thu, 24 Mar 2005 20:37:00 -0000 From: Daniel Jacobowitz To: Ramana Radhakrishnan Cc: gdb@sources.redhat.com, amit bhor Subject: Re: RFC : Handling breakpoints on archs. with imprecise exceptions. Message-ID: <20050324203814.GA7529@nevyn.them.org> Mail-Followup-To: Ramana Radhakrishnan , gdb@sources.redhat.com, amit bhor References: <42431904.7010708@codito.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42431904.7010708@codito.com> User-Agent: Mutt/1.5.6+20040907i X-SW-Source: 2005-03/txt/msg00217.txt.bz2 On Fri, Mar 25, 2005 at 01:16:12AM +0530, Ramana Radhakrishnan wrote: > Hi, > > While looking at a GDB port to a processor that has > imprecise exceptions/ interrupts i.e. the equivalent of a > software breakpoint would require 4 instructions to stop. > With my research I was unable to find any GDB port that > needed to handle such a case. > > The mechanism that is in mind is the following for setting > breakpoints. It sounds plausible, although messy. Does a single-instruction branch always give you enough range to reach a breakpoint table? I suspect you could handle this by wrapping gdbarch_read_pc, so that a "breakpoint" at a particular "pc" would appear to stop there rather than in the table. Be sure to restore the correct pc at that point. That and breakpoint_from_pc may be all the hooks you need. And maybe hooks in target_insert_breakpoint/target_remove_breakpoint to reference count. > a. Define gdbarch_adjust_breakpoint_address in the backend > to store the mapping in the backend for the PC at which > breakpoint has been set to the actual value for the PC where > the breakpoint would be reported to have been hit. > > b. Define deprecated_target_wait_hook in the backend to > restore the actual value of the PC for GDB to continue with > its work.However as this is a deprecated hook I would not > like to use this in a new port. > > c. Add a new notify_backend_breakpoint_deleted_hook since > the backend needs notification for the breakpoint being > deleted and hence free an entry in the breakpoint table. You should be hooking insert/remove breakpoint, not add/delete user breakpoint. Does gdbarch_read_pc do everything you need for the wait_hook? You can update the PC from there if necessary. -- Daniel Jacobowitz CodeSourcery, LLC