From owner-freebsd-hackers Sun Aug 26 10:28:20 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from mass.dis.org (mass.dis.org [216.240.45.41]) by hub.freebsd.org (Postfix) with ESMTP id CE2F437B409; Sun, 26 Aug 2001 10:28:16 -0700 (PDT) (envelope-from msmith@mass.dis.org) Received: from mass.dis.org (localhost [127.0.0.1]) by mass.dis.org (8.11.4/8.11.3) with ESMTP id f7QHXVr00963; Sun, 26 Aug 2001 10:33:31 -0700 (PDT) (envelope-from msmith@mass.dis.org) Message-Id: <200108261733.f7QHXVr00963@mass.dis.org> X-Mailer: exmh version 2.1.1 10/15/1999 To: Ronald G Minnich Cc: Mike Smith , djohnson , freebsd-hackers@FreeBSD.ORG Subject: Re: PCI Enumeration In-reply-to: Your message of "Sun, 26 Aug 2001 10:55:59 MDT." Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sun, 26 Aug 2001 10:33:31 -0700 From: Mike Smith Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG > On Sat, 25 Aug 2001, Mike Smith wrote: > > > I/O space is easy, but memory space is hard. Userspace access to > > physical memory is a big no-no in the *nix world. > > I want to disagree just a bit. If you look at myrinet, or the many fpga > cards, it's the standard modus operandi. You have to do it that way. You're not disagreeing; you're talking at cross purposes. Direct userspace access to physical memory is bad. The ability for user processes to access *specific* physical memory via kernel-owned protection paths is often necessary to meet specific performance goals, or to overcome lame hardware designs. -- ... every activity meets with opposition, everyone who acts has his rivals and unfortunately opponents also. But not because people want to be opponents, rather because the tasks and relationships force people to take different points of view. [Dr. Fritz Todt] V I C T O R Y N O T V E N G E A N C E To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message