From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from db9outboundpool.messaging.microsoft.com (mail-db9lp0250.outbound.messaging.microsoft.com [213.199.154.250]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "MSIT Machine Auth CA 2" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 5D8752C0343 for ; Fri, 28 Jun 2013 11:52:33 +1000 (EST) Date: Thu, 27 Jun 2013 20:52:20 -0500 From: Scott Wood Subject: Re: [PATCH 1/2] powerpc: enable the relocatable support for the fsl booke 32bit kernel To: Kevin Hao References: <1372298434-20220-2-git-send-email-haokexin@gmail.com> <1372363114.8183.54@snotra> <20130628013637.GA3173@pek-khao-d1.corp.ad.wrs.com> In-Reply-To: <20130628013637.GA3173@pek-khao-d1.corp.ad.wrs.com> (from haokexin@gmail.com on Thu Jun 27 20:36:37 2013) Message-ID: <1372384340.8183.62@snotra> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; format=Flowed Cc: linuxppc List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 06/27/2013 08:36:37 PM, Kevin Hao wrote: > On Thu, Jun 27, 2013 at 02:58:34PM -0500, Scott Wood wrote: > > On 06/26/2013 09:00:33 PM, Kevin Hao wrote: > > >This is based on the codes in the head_44x.S. Since we always =20 > align to > > >256M before mapping the PAGE_OFFSET for a relocatable kernel, we =20 > also > > >change the init tlb map to 256M size. > > > > Why 256M? >=20 > For two reasons: > 1. This is the size which both e500v1 and e500v2 support. > 2. Since we always use the PAGE_OFFSET as 0xc0000000, the 256M is > max alignment value we can use for this virtual address. 0xc0000000 is 1G-aligned, so I don't see why 256M is the maximum (after =20 verifying that enough memory is present with the right alignment, of =20 course). The TLB1 savings would probably not be enough to justify =20 figuring that out, though. -Scott=