Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 20 Jun 2002 10:50:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 20 Jun 2002 10:50:40 -0400 Received: from twin.jikos.cz ([217.11.236.59]:58014 "EHLO twin.jikos.cz") by vger.kernel.org with ESMTP id ; Thu, 20 Jun 2002 10:50:38 -0400 Date: Thu, 20 Jun 2002 16:50:26 +0200 (CEST) From: Jirka Kosina To: Brian Gerst cc: devnull@adc.idt.com, Subject: Re: >3G Memory support In-Reply-To: <3D11E9ED.7060101@didntduck.org> Message-ID: References: <3D11E9ED.7060101@didntduck.org> 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: 1082 Lines: 27 On Thu, 20 Jun 2002, Brian Gerst wrote: > > What limits user space to 3GB. > Hardware limitations imposed by the x86 architecture. The x86 only has > _one_ virtual address space, which has to be shared by user space and > kernel space. It is not possible to give user space more virtual > address space without taking it away from the kernel. You can theoretically run kernel in one task (I mean "task" in the Intel-processor-meaning of the word ;) ) and userspace programs in another task, which will result in having 4GB of memory for both of them, won't it? I know, there would be big compilcations - for example copying data betweeen userspace and kernelspace should be problem, and if implemented, I can't imagine how to do it considerably fast...which is IMHO the main reason why it isn't done such way. -- JiKos. - 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/