Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269208AbUIBW6h (ORCPT ); Thu, 2 Sep 2004 18:58:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269163AbUIBWzd (ORCPT ); Thu, 2 Sep 2004 18:55:33 -0400 Received: from fw.osdl.org ([65.172.181.6]:3756 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S269189AbUIBWxi (ORCPT ); Thu, 2 Sep 2004 18:53:38 -0400 Date: Thu, 2 Sep 2004 15:53:34 -0700 (PDT) From: Linus Torvalds To: Tom Vier cc: linux-kernel@vger.kernel.org Subject: Re: silent semantic changes with reiser4 In-Reply-To: <20040902223557.GA15505@zero> Message-ID: References: <20040825234629.GF2612@wiggy.net> <1093480940.2748.35.camel@entropy> <20040826044425.GL5414@waste.org> <1093496948.2748.69.camel@entropy> <20040826053200.GU31237@waste.org> <20040826075348.GT1284@nysv.org> <20040826163234.GA9047@delft.aura.cs.cmu.edu> <20040831033950.GA32404@zero> <20040902223557.GA15505@zero> 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: 1489 Lines: 35 On Thu, 2 Sep 2004, Tom Vier wrote: > > > Not user space. They may be "ring 3" from a CPU standpoint, but they > > aren't user space from a _user_ standpoint - it's still very much a > > separate address space, with domain protection. > > How are they different from regular user procs, other then being trusted to > manage certain resources? Ehh, they are separate the same way "inetd" is separate. It's not a _user_ proc, it's a system proc. The user can't actually do anything about it. In many ways UNIX _is_ a microkernel. It does nonessential stuff in "user space". Anything that is critical for performance or the working of the machine is in kernel space. The big difference between UNIX and what people _call_ "microkernels" is that UNIX has a very functional and sane partitioning of what is a critical thing. But from a kernel _protection_ angle, the only part that is important is that the services be in some protected domain. That was what started this discussion: 99% of what the kernel does is protecting shared data. Whether it does so by passing it on to some trusted third party or not is an implementation issue, and is totally pointless from a user standpoint, since the user won't see it anyway. Linus - 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/