From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from hancock.sc.steeleye.com (nat9.steeleye.com [65.114.3.137]) by dsl2.external.hp.com (Postfix) with ESMTP id 464CC4845 for ; Tue, 30 Sep 2003 07:30:03 -0600 (MDT) Received: from mulgrave-w.il.steeleye.com (il-ppp.sc.steeleye.com [172.17.6.240]) by hancock.sc.steeleye.com (8.11.6/linuxconf) with ESMTP id h8UDHNq08517; Tue, 30 Sep 2003 09:17:23 -0400 Subject: Re: [parisc-linux] MAX_ADDRESS. From: James Bottomley To: knaresh@india.hp.com Cc: Matthew Wilcox , PARISC list In-Reply-To: <3F7975FE.58C276D9@india.hp.com> References: <3F7915A7.1F54379@india.hp.com> <20030930120636.GV24824@parcelfarce.linux.theplanet.co.uk> <3F7975FE.58C276D9@india.hp.com> Content-Type: text/plain Date: 30 Sep 2003 08:17:22 -0500 Message-Id: <1064927843.2065.3.camel@mulgrave> Mime-Version: 1.0 Sender: parisc-linux-admin@lists.parisc-linux.org Errors-To: parisc-linux-admin@lists.parisc-linux.org List-Help: List-Post: List-Subscribe: , List-Id: parisc-linux developers list List-Unsubscribe: , List-Archive: On Tue, 2003-09-30 at 07:24, Naresh wrote: > MAX_ADDRESS has nothing to do with DISCONTIGMEM. Its definition is generic( > pgtable.h), although it is not used anywhere. I just happened to see the comment in > the DISCONTIGMEM code. Even if DISCONTIGMEM is turned off, there is no check for > MAX_ADDRESS before the call to 'map_pages()' in 'pagetable_init( )', which is why I > would like to know if MAX_ADDRESS can be ignored. No. It does represent the highest virtual address possible. Linux has 3 levels of page tables, so on a 64 bit kernel (8 bytes per pte and 8 bytes per pte page pointer etc), we can address a maximum of 512GB with 4k pages. James