From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from QMTA08.westchester.pa.mail.comcast.net (qmta08.westchester.pa.mail.comcast.net [76.96.62.80]) by ozlabs.org (Postfix) with ESMTP id 7F759DDF99 for ; Thu, 22 May 2008 16:46:20 +1000 (EST) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii From: Roland McGrath To: Paul Mackerras Subject: Re: [RFC] 4xx hardware watchpoint support In-Reply-To: Paul Mackerras's message of Thursday, 22 May 2008 13:51:52 +1000 <18484.60888.981390.893747@cargo.ozlabs.ibm.com> References: <1211391577.6232.15.camel@gargoyle> <18484.60888.981390.893747@cargo.ozlabs.ibm.com> Message-Id: <20080522064613.088AB26FA24@magilla.localdomain> Date: Wed, 21 May 2008 23:46:13 -0700 (PDT) Cc: ppc-dev List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , > I would think there would be a different REQUEST value to mean "set a > hardware breakpoint". Roland McGrath (cc'd) might be able to tell us > what other architectures do. Other architectures don't give a good model to follow. (If anything, they just trivally virtualize their own idiosyncratic hardware.) What I want to see done for this in the future is reviving and finishing the hw_breakpoint work begun by Alan Stern, and porting that to each arch's particular hardware features. On that we'd build any new interfaces in abstract machine-independent terms, just describing the constraints of what the hardware can do, rather than having the user interface involve mimicking hardware encodings. (The existing hardware-idiosyncratic ptrace interfaces would tie into hw_breakpoint for backward compatibility.) Thanks, Roland