From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758747AbZBDXqA (ORCPT ); Wed, 4 Feb 2009 18:46:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752641AbZBDXpu (ORCPT ); Wed, 4 Feb 2009 18:45:50 -0500 Received: from yw-out-2324.google.com ([74.125.46.31]:30529 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752163AbZBDXpt (ORCPT ); Wed, 4 Feb 2009 18:45:49 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=EmDRy/fMyhg0CZnFTbuF+P8TVQL+PMlFjs4yqqFy8kY0+9pnlX4xvTygLToGTG511M b4WRzMD1dcctOiIMHso8rR/kpwXsUcjoLbVLPm7E2rcnXDdTY2nT5/fx7N7YomlkmqVa 3xOO4Nn3s7bGk0YuYyNoRN48xF7Up7iqdtVlI= MIME-Version: 1.0 In-Reply-To: <20090204150507.665b5b7c.akpm@linux-foundation.org> References: <20090204150507.665b5b7c.akpm@linux-foundation.org> Date: Wed, 4 Feb 2009 15:45:47 -0800 Message-ID: Subject: Re: [patch/rfc] eventfd semaphore-like behavior From: Ulrich Drepper To: Andrew Morton Cc: Davide Libenzi , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, mtk.manpages@gmail.com, linux-api@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 4, 2009 at 3:05 PM, Andrew Morton wrote: > How would you recommend that userspace determine whether its kernel > supports this feature, bearing in mind that someone might backport this > patch into arbitrarily earlier kernel versions? fd = eventfd2 (CNT, EFD_SEMAPHORE); if (fd == -1 && errno == EINVAL) puts("cannot handled EFD_SEMAPHORE");