From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753287AbYGWHou (ORCPT ); Wed, 23 Jul 2008 03:44:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751266AbYGWHol (ORCPT ); Wed, 23 Jul 2008 03:44:41 -0400 Received: from out3.smtp.messagingengine.com ([66.111.4.27]:60066 "EHLO out3.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750793AbYGWHol (ORCPT ); Wed, 23 Jul 2008 03:44:41 -0400 X-Sasl-enc: pVbckYbAwa/6ni6gMQjkDwbw/XveMkGC7AMSBd3zPks1 1216799080 Message-ID: <4886E164.2070304@ladisch.de> Date: Wed, 23 Jul 2008 09:44:36 +0200 From: Clemens Ladisch User-Agent: Thunderbird 2.0.0.14 (Windows/20080421) MIME-Version: 1.0 To: David Brownell CC: lkml , bob.picco@hp.com, venkatesh.pallipadi@intel.com, Vojtech Pavlik , the arch/x86 maintainers Subject: Re: [patch 2.6.26] /dev/hpet - fixes and cleanup References: <200807221508.56672.david-b@pacbell.net> In-Reply-To: <200807221508.56672.david-b@pacbell.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Brownell wrote: > * Tighten and correct the userspace interface code > ... > + only open comparators that have an interrupt, and can thus > perform "real work" This prevents userspace applications from doing mmap() on /dev/hpet even if there is no interrupt. This seems to be the only part of the userspace interface that is used in practice. Because of the availability of POSIX timers, it might make sense to deprecate the HPET ioctl interface. > And re that kernel interface: IMO, worth having a relatively > generic interface for hardware timers instead of inventing a new > interface for each new bit of hardware. AFAIK it was intended to be similar to the RTC callback interface, but that was before the generic high-precision timer stuff was introduced. Regards, Clemens