From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964821AbWGYTLB (ORCPT ); Tue, 25 Jul 2006 15:11:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964820AbWGYTLB (ORCPT ); Tue, 25 Jul 2006 15:11:01 -0400 Received: from terminus.zytor.com ([192.83.249.54]:21657 "EHLO terminus.zytor.com") by vger.kernel.org with ESMTP id S964821AbWGYTLA (ORCPT ); Tue, 25 Jul 2006 15:11:00 -0400 Message-ID: <44C66C91.8090700@zytor.com> Date: Tue, 25 Jul 2006 12:10:09 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 1.5.0.4 (X11/20060614) MIME-Version: 1.0 To: Neil Horman CC: Segher Boessenkool , linux-kernel@vger.kernel.org, a.zummo@towertech.it, jg@freedesktop.org Subject: Re: [PATCH] RTC: Add mmap method to rtc character driver References: <20060725174100.GA4608@hmsreliant.homelinux.net> <03BCDC7F-13D9-42FC-86FC-30C76FD3B3B8@kernel.crashing.org> <20060725182833.GE4608@hmsreliant.homelinux.net> In-Reply-To: <20060725182833.GE4608@hmsreliant.homelinux.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Neil Horman wrote: > > In general I agree, but that only works if you operate on a platform that > supports virtual syscalls, and has vdso configured. I'm not overly familiar > with vdso, but I didn't think vdso could be supported on all platforms/arches. > This seems like it might be a nice addition in those cases. > Not really. This introduces a potentially very difficult support user-visible interface. Consider a tickless kernel -- you might end up taking tick interrupts ONLY to update this page, since you don't have any way of knowing when userspace wants to look at it. -hpa