From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22EB8C04AB3 for ; Mon, 27 May 2019 12:22:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E91C220673 for ; Mon, 27 May 2019 12:22:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727091AbfE0MWl (ORCPT ); Mon, 27 May 2019 08:22:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37288 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726071AbfE0MWk (ORCPT ); Mon, 27 May 2019 08:22:40 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8A1FE309265A; Mon, 27 May 2019 12:22:40 +0000 (UTC) Received: from sirius.home.kraxel.org (ovpn-116-59.ams2.redhat.com [10.36.116.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1B84B46466; Mon, 27 May 2019 12:22:38 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 57F9211AAB; Mon, 27 May 2019 14:22:37 +0200 (CEST) Date: Mon, 27 May 2019 14:22:37 +0200 From: Gerd Hoffmann To: Zhenyu Wang Cc: Tina Zhang , intel-gvt-dev@lists.freedesktop.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, alex.williamson@redhat.com, hang.yuan@intel.com, zhiyuan.lv@intel.com Subject: Re: [PATCH 1/2] vfio: ABI for setting mdev display flip eventfd Message-ID: <20190527122237.uhd7qm62h6wfv5w7@sirius.home.kraxel.org> References: <20190527084312.8872-1-tina.zhang@intel.com> <20190527084312.8872-2-tina.zhang@intel.com> <20190527090741.GE29553@zhen-hp.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190527090741.GE29553@zhen-hp.sh.intel.com> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Mon, 27 May 2019 12:22:40 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 27, 2019 at 05:07:41PM +0800, Zhenyu Wang wrote: > On 2019.05.27 16:43:11 +0800, Tina Zhang wrote: > > Add VFIO_DEVICE_SET_GFX_FLIP_EVENTFD ioctl command to set eventfd > > based signaling mechanism to deliver vGPU framebuffer page flip > > event to userspace. > > Should we add probe to see if driver can support gfx flip event? Userspace can simply call VFIO_DEVICE_SET_GFX_FLIP_EVENTFD and see if it worked. If so -> use the eventfd. Otherwise take the fallback path (timer based polling). I can't see any advantage a separate feature probe steps adds. cheers, Gerd