From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935743AbeBWTE0 (ORCPT ); Fri, 23 Feb 2018 14:04:26 -0500 Received: from mga17.intel.com ([192.55.52.151]:30784 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933966AbeBWTEY (ORCPT ); Fri, 23 Feb 2018 14:04:24 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,383,1515484800"; d="scan'208";a="206556621" Date: Fri, 23 Feb 2018 11:02:04 -0800 From: Dongwon Kim To: Roger Pau =?iso-8859-1?Q?Monn=E9?= Cc: linux-kernel@vger.kernel.org, linaro-mm-sig@lists.linaro.org, xen-devel@lists.xenproject.org, sumit.semwal@linaro.org, dri-devel@lists.freedesktop.org, mateuszx.potrola@intel.com Subject: Re: [Xen-devel] [RFC PATCH v2 2/9] hyper_dmabuf: architecture specification and reference guide Message-ID: <20180223190204.GA28019@downor-Z87X-UD5H> References: <20180214015008.9513-1-dongwon.kim@intel.com> <20180214015008.9513-3-dongwon.kim@intel.com> <20180223161500.xpbqnpsxihoxi5o4@MacBook-Pro-de-Roger.local> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180223161500.xpbqnpsxihoxi5o4@MacBook-Pro-de-Roger.local> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks for your comment, Roger I will try to polish this doc and resubmit. (I put some comments below as well.) On Fri, Feb 23, 2018 at 04:15:00PM +0000, Roger Pau Monné wrote: > On Tue, Feb 13, 2018 at 05:50:01PM -0800, Dongwon Kim wrote: > > Reference document for hyper_DMABUF driver > > > > Documentation/hyper-dmabuf-sharing.txt > > This should likely be patch 1 in order for reviewers to have the > appropriate context. > > > > > Signed-off-by: Dongwon Kim > > --- > > Documentation/hyper-dmabuf-sharing.txt | 734 +++++++++++++++++++++++++++++++++ > > 1 file changed, 734 insertions(+) > > create mode 100644 Documentation/hyper-dmabuf-sharing.txt > > > > diff --git a/Documentation/hyper-dmabuf-sharing.txt b/Documentation/hyper-dmabuf-sharing.txt > > new file mode 100644 > > index 000000000000..928e411931e3 > > --- /dev/null > > +++ b/Documentation/hyper-dmabuf-sharing.txt > > @@ -0,0 +1,734 @@ > > +Linux Hyper DMABUF Driver > > + > > +------------------------------------------------------------------------------ > > +Section 1. Overview > > +------------------------------------------------------------------------------ > > + > > +Hyper_DMABUF driver is a Linux device driver running on multiple Virtual > > +achines (VMs), which expands DMA-BUF sharing capability to the VM environment > > +where multiple different OS instances need to share same physical data without > > +data-copy across VMs. > > + > > +To share a DMA_BUF across VMs, an instance of the Hyper_DMABUF drv on the > > +exporting VM (so called, “exporter”) imports a local DMA_BUF from the original > > +producer of the buffer, > > The usage of export and import in the above sentence makes it almost > impossible to understand. Ok, it looks confusing. I think the problem is that those words are used for both local and cross-VMs cases. I will try to clarify those. > > > then re-exports it with an unique ID, hyper_dmabuf_id > > +for the buffer to the importing VM (so called, “importer”). > > And this is even worse. > > Maybe it would help to have some kind of flow diagram of all this > import/export operations, but please read below. I will add a diagram here. > > > + > > +Another instance of the Hyper_DMABUF driver on importer registers > > +a hyper_dmabuf_id together with reference information for the shared physical > > +pages associated with the DMA_BUF to its database when the export happens. > > + > > +The actual mapping of the DMA_BUF on the importer’s side is done by > > +the Hyper_DMABUF driver when user space issues the IOCTL command to access > > +the shared DMA_BUF. The Hyper_DMABUF driver works as both an importing and > > +exporting driver as is, that is, no special configuration is required. > > +Consequently, only a single module per VM is needed to enable cross-VM DMA_BUF > > +exchange. > > IMHO I need a more generic view of the problem you are trying to solve > in the overview section. I've read the full overview, and I still have > no idea why you need all this. I will add some more paragrahs here to give some more generic view (and possibly diagrams) of this driver. > > I think the overview should contain at least: > > 1. A description of the problem you are trying to solve. > 2. A high level description of the proposed solution. > 3. How the proposed solution deals with the problem described in 1. > > This overview is not useful for people that don't know which problem > you are trying to solve, like myself. Thanks again. > > Thanks, Roger. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dongwon Kim Subject: Re: [Xen-devel] [RFC PATCH v2 2/9] hyper_dmabuf: architecture specification and reference guide Date: Fri, 23 Feb 2018 11:02:04 -0800 Message-ID: <20180223190204.GA28019@downor-Z87X-UD5H> References: <20180214015008.9513-1-dongwon.kim@intel.com> <20180214015008.9513-3-dongwon.kim@intel.com> <20180223161500.xpbqnpsxihoxi5o4@MacBook-Pro-de-Roger.local> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by gabe.freedesktop.org (Postfix) with ESMTPS id B87276F152 for ; Fri, 23 Feb 2018 19:04:24 +0000 (UTC) Content-Disposition: inline In-Reply-To: <20180223161500.xpbqnpsxihoxi5o4@MacBook-Pro-de-Roger.local> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Roger Pau =?iso-8859-1?Q?Monn=E9?= Cc: 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