From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751563AbWGYU0q (ORCPT ); Tue, 25 Jul 2006 16:26:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751562AbWGYU0p (ORCPT ); Tue, 25 Jul 2006 16:26:45 -0400 Received: from terminus.zytor.com ([192.83.249.54]:41861 "EHLO terminus.zytor.com") by vger.kernel.org with ESMTP id S1751544AbWGYU0o (ORCPT ); Tue, 25 Jul 2006 16:26:44 -0400 Message-ID: <44C67E1A.7050105@zytor.com> Date: Tue, 25 Jul 2006 13:24:58 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 1.5.0.4 (X11/20060614) MIME-Version: 1.0 To: Dave Airlie CC: Neil Horman , 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> <44C66C91.8090700@zytor.com> <20060725192138.GI4608@hmsreliant.homelinux.net> <20060725194733.GJ4608@hmsreliant.homelinux.net> <21d7e9970607251304n5681bf44gc751c21fd79be99d@mail.gmail.com> In-Reply-To: <21d7e9970607251304n5681bf44gc751c21fd79be99d@mail.gmail.com> 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 Dave Airlie wrote: > > So far the requirements are pretty much not high resolution but is > accurate and increasing. so like 10ms is fine, the current X timer is > in the 20ms range. > > I think an mmap'ed page with whatever cgt(CLOCK_MONOTONIC) returns > would be very good, but it might be nice to implement some sort of new > generic /dev that X can mmap and each arch can do what they want in > it, > > I'm wondering why x86 doesn't have gettimeofday vDSO (does x86 have > proper vDSO support at all apart from sysenter?), > The i386 vdso right now has only two entry points, as far as I can tell: system call and signal return. There is no reason it couldn't have more than that. A low-resolution and a high-resolution gettimeofday might be a good idea. -hpa