From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 7 Jan 2003 23:10:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 7 Jan 2003 23:10:43 -0500 Received: from nat-pool-rdu.redhat.com ([66.187.233.200]:56121 "EHLO devserv.devel.redhat.com") by vger.kernel.org with ESMTP id ; Tue, 7 Jan 2003 23:10:42 -0500 Date: Tue, 7 Jan 2003 23:19:22 -0500 From: Pete Zaitcev Message-Id: <200301080419.h084JMT10615@devserv.devel.redhat.com> To: Larry McVoy cc: linux-kernel@vger.kernel.org Subject: User mode drivers (Honest does not pay here ...) In-Reply-To: References: <20030107232820.GB24664@merlin.emma.line.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > I may be showing my ignorance here (won't be the first time) but this makes > me wonder if Linux could provide a way to do "user level drivers". It is a question often asked in comp.os.linux.development.system. If performance penalties and security problems are no obstacle, a lot of hardware can be serviced with a user mode driver, except one that requires interrupts to operate. There is no way to deliver an interrupt safely to the user mode, because a device specific deactivation or ack-ing must be performed before interrupts are enabled (on i386 at least). Other problems can be worked around with ioperm and friends. -- Pete