Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267856AbUIVEja (ORCPT ); Wed, 22 Sep 2004 00:39:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267864AbUIVEja (ORCPT ); Wed, 22 Sep 2004 00:39:30 -0400 Received: from ares.cs.Virginia.EDU ([128.143.137.19]:12790 "EHLO ares.cs.Virginia.EDU") by vger.kernel.org with ESMTP id S267856AbUIVEj2 (ORCPT ); Wed, 22 Sep 2004 00:39:28 -0400 Date: Wed, 22 Sep 2004 00:39:22 -0400 (EDT) From: Ronghua Zhang To: Robert Love cc: linux-kernel@vger.kernel.org Subject: Re: Does ZONE_HIGHMEM exist on machines with 1G memeory In-Reply-To: <1095826387.2454.101.camel@localhost> Message-ID: References: <1095826387.2454.101.camel@localhost> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 931 Lines: 27 But why cannot we simply map the whole physical memory into the 1GB kernel virtual address space? In this case, we don't need to reserve any address space for the permanent or temporary mapping. Am I missing something here? Thanks RZ On Wed, 22 Sep 2004, Robert Love wrote: > On Tue, 2004-09-21 at 23:09 -0400, Ronghua Zhang wrote: > > > This may be a dumb question. But it seems to me that when the machine > > has 1GB memory, it can be mapped to the 1GB kernel virtual address space. > > Do we still need ZONE_HIGHMEM in this case? Please CC any follow-up to me. > > Thanks > > Highmem is actually everything above 896MB ... so, yes, you need > ZONE_HIGHMEM. > > Robert Love > > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/