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 E396CB6EF0 for ; Wed, 6 Apr 2011 09:39:21 +1000 (EST) Subject: Re: [PATCH] powerpc/book3e: Fix extlb size From: Benjamin Herrenschmidt To: Kumar Gala In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Date: Wed, 06 Apr 2011 09:39:09 +1000 Message-ID: <1302046749.2549.186.camel@pasglop> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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.