From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 954FBB6EEE for ; Wed, 6 Apr 2011 11:46:03 +1000 (EST) Subject: Re: [PATCH] powerpc/book3e: Fix extlb size Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=us-ascii From: Kumar Gala In-Reply-To: <1302046749.2549.186.camel@pasglop> Date: Tue, 5 Apr 2011 20:45:48 -0500 Message-Id: <52FDCC6C-2F2F-47CC-8E6D-02A65FD21BCF@kernel.crashing.org> References: <1302046749.2549.186.camel@pasglop> To: Benjamin Herrenschmidt Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Apr 5, 2011, at 6:39 PM, Benjamin Herrenschmidt wrote: > On Tue, 2011-04-05 at 07:41 -0500, Kumar Gala wrote: >>> Rework it to make it a bit clearer, and also correct. We want 3 save >>> areas, each EX_TLB_SIZE _bytes_. >> >> Where does the 3 come from? I have a guess, and think its possible we >> (FSL) want 4? > > Wrong guess :-) It's not about exception levels. It's about how much > the handler can re-enter (2 with E.PT, 3 with virtual linear) > > For MC's, CRITs etc... which we don't support on Book3E 64-bit at this > stage, you'll have to probably backup the whole area... that or move > the TLB frame pointer SPR to a separate set of 3 levels, but then you'd > have to fix the code that makes assumption about level 0 being at a > fixed offset in the PACA and instead use alignment tricks. We need that > because that's how we "reset" the TLB frame when a second level finds > a fault. > > Cheers, > Ben. Gotcha, can we add a comment here about what the '3' is about. - k