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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no 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 43243C11F68 for ; Fri, 2 Jul 2021 17:54:51 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E234A6140E for ; Fri, 2 Jul 2021 17:54:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E234A6140E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 36EC16E197; Fri, 2 Jul 2021 17:54:50 +0000 (UTC) Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [46.235.227.227]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9E2736E197 for ; Fri, 2 Jul 2021 17:54:49 +0000 (UTC) Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id C9B661F44FD0; Fri, 2 Jul 2021 18:54:47 +0100 (BST) Date: Fri, 2 Jul 2021 19:54:44 +0200 From: Boris Brezillon To: Alyssa Rosenzweig Subject: Re: [PATCH v3 5/7] drm/panfrost: Add a new ioctl to submit batches Message-ID: <20210702195444.010bbb7b@collabora.com> In-Reply-To: References: <20210702143225.3347980-1-boris.brezillon@collabora.com> <20210702143225.3347980-6-boris.brezillon@collabora.com> <20210702173843.44b3e322@collabora.com> Organization: Collabora X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jason Ekstrand , Tomeu Vizoso , dri-devel@lists.freedesktop.org, Steven Price , Rob Herring , Alyssa Rosenzweig , Robin Murphy Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, 2 Jul 2021 12:49:55 -0400 Alyssa Rosenzweig wrote: > > > Why is there padding instead of putting point first? > > > > We can move the point field first, but we need to keep the explicit > > padding: the struct has to be 64bit aligned because of the __u64 field > > (which the compiler takes care of) but if we don't have an explicit > > padding, the unused 32bits are undefined, which might cause trouble if > > we extend the struct at some point, since we sort of expect that old > > userspace keep this unused 32bit slot to 0, while new users set > > non-zero values if they have to. > > Makes sense. Reordering still probably makes sense. Actually, I can't re-order if I want the new in_syncs parser to work with the old ioctl(), which you and Steven asked me to do :-).