Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270491AbUJTUIh (ORCPT ); Wed, 20 Oct 2004 16:08:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269214AbUJTUIP (ORCPT ); Wed, 20 Oct 2004 16:08:15 -0400 Received: from clock-tower.bc.nu ([81.2.110.250]:15835 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id S270491AbUJTUCc (ORCPT ); Wed, 20 Oct 2004 16:02:32 -0400 Subject: Re: Running user processes in kernel mode; Java and .NET support in kernel From: Alan Cox To: Kendall Bennett Cc: Linux Kernel Mailing List In-Reply-To: <4173BC21.24859.11899F91@localhost> References: <82fa66380410152111143f75ec@mail.gmail.com> <4173BC21.24859.11899F91@localhost> Content-Type: text/plain Content-Transfer-Encoding: 7bit Message-Id: <1098298776.12366.16.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) Date: Wed, 20 Oct 2004 19:59:37 +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1109 Lines: 24 On Llu, 2004-10-18 at 20:50, Kendall Bennett wrote: > Alan Cox wrote: > > > Why would I care ? I need the MMU for paging and to avoid > > fragmentation of the system. If I have the MMU on then memory > > protection checks are free. > > > > Except in 4G/4G mode syscalls are extremely cheap too nowdays. > > Yes, but kernel mode support in user programs would allow user mode > device drivers to do stuff that currently cannot be done at all from user > space such as handling interrupts and scheduling DMA operations. DMA doesn't need the kernel's help except for when you want to manage security - DRI is quite special in that way. A driver to provide mmapable DMA memory is trivial. IRQ's are *much* harder because you have to clear the IRQ source in the IRQ handler, but people have code that does this and then sends signals. - 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/