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From: Roland McGrath <roland@redhat.com>
To: prasad@linux.vnet.ibm.com
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Alan Stern <stern@rowland.harvard.edu>, akpm@linux-foundation.org,
       mingo@elte.hu, jason.wessel@windriver.com, avi@qumranet.com,
       richardj_moore@uk.ibm.com
Subject: Re: [RFC Patch 2/9] x86 architecture implementation of Hardware
	Breakpoint interfaces
In-Reply-To: K.Prasad's message of  Thursday, 9 October 2008 00:53:48 +0530 <20081008192348.GB4989@in.ibm.com>
References: <20081008192044.GA4510@in.ibm.com>
	<20081008192348.GB4989@in.ibm.com>
Message-Id: <20081016025728.3F92B1544CB@magilla.localdomain>
Date: Wed, 15 Oct 2008 19:57:28 -0700 (PDT)
Sender: linux-kernel-owner@vger.kernel.org
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Lines: 21

I'm leaving aside the single-step stuff, which I just posted about.

I'm also concerned about getting RF right here.  We need to make sure that
every place that warps ->ip away somewhere also clears RF.  In case of
instruction breakpoints in user space, we might also want to mask RF from
being seen/changed via ptrace/user_regset (a bit like is done for TF).

I'm a little inclined to do a first x86 version without instruction
breakpoint support and hash out the rest of the code for a bit.  Then add
instruction breakpoints in a later patch.  (Not that it has to be a lot
later or anything.  Just to table the detailed review of RF fiddling until
after most of the meaty stuff is pretty baked.)


Thanks,
Roland
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