From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out5-smtp.messagingengine.com (out5-smtp.messagingengine.com [66.111.4.29]) by dpdk.org (Postfix) with ESMTP id DD0582C13 for ; Wed, 28 Jun 2017 15:30:34 +0200 (CEST) Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.nyi.internal (Postfix) with ESMTP id 7FD4F20B7F; Wed, 28 Jun 2017 09:30:34 -0400 (EDT) Received: from frontend1 ([10.202.2.160]) by compute1.internal (MEProxy); Wed, 28 Jun 2017 09:30:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=monjalon.net; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-sender :x-me-sender:x-sasl-enc:x-sasl-enc; s=mesmtp; bh=erjnycDEuFQOHWH a0DhxGG4MvQpMysZN2unVO8fNqo4=; b=hUoKnq74MuKAgSMi3dVxfCw4jgUwBkR 6nM9AMjgCgPzivX2lDaHYfFvwH/LduwKB/dV9vCPobkKXsW6Y9YGe1gwXCyM1Fqc LCOkoxpLCAADYB4vFynPTi0r8XEPUMsV1lLIZWVyClGp7g7R0ZLuZ3l6jEHUXmpq fidL3anZ6QQY= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:in-reply-to:message-id:mime-version:references :subject:to:x-me-sender:x-me-sender:x-sasl-enc:x-sasl-enc; s= fm1; bh=erjnycDEuFQOHWHa0DhxGG4MvQpMysZN2unVO8fNqo4=; b=NNORsLyJ /lHtTlNC6tDFBWYdKKanpyDWBvEsvD0HB82MUlI79jSLfHPdpp7WaTY20+XKKEgO u+Xzw065OdgJTf6jp1P3r7jKB7VGLr4A5+6efwHwj0BtW3Bip66ZbOhDyzVbyZI3 uh924HxJSoZvcCJW36sOm5iLK8OhlkLsXD3EjLd9xruOzK6bo4qBZBPIeP1WUErB EwMUK/djju+K+e5iEn+dTgNDjAhXiywxB5Z1/G7m3HURUvCjPExWVoR48fVuHDC3 f7/x0n8vtu1QNG98jKZs5h7FcAZBu1BiYGocwwFOyok77Q0nICG5EW7GFtNHsS5j dWXn7hiNZphKWg== X-ME-Sender: X-Sasl-enc: mPthbv3Nsj5GQOQXUTKcyZAWct918fLQcQQq2aeF1fS9 1498656634 Received: from xps.localnet (184.203.134.77.rev.sfr.net [77.134.203.184]) by mail.messagingengine.com (Postfix) with ESMTPA id 2899C7E8BE; Wed, 28 Jun 2017 09:30:34 -0400 (EDT) From: Thomas Monjalon To: Jan Blunck Cc: dev@dpdk.org, Gaetan Rivet Date: Wed, 28 Jun 2017 15:30:33 +0200 Message-ID: <1765263.t0XI3ojoND@xps> In-Reply-To: References: <14287370.n4WKZa6dWl@xps> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Subject: Re: [dpdk-dev] [PATCH v6 05/11] bus: introduce hotplug functionality X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 28 Jun 2017 13:30:35 -0000 28/06/2017 15:09, Jan Blunck: > On Wed, Jun 28, 2017 at 2:11 PM, Thomas Monjalon wrote: > > 28/06/2017 13:58, Jan Blunck: > >> On Wed, Jun 28, 2017 at 1:44 PM, Thomas Monjalon wrote: > >> > 27/06/2017 21:03, Jan Blunck: > >> >> On Tue, Jun 27, 2017 at 6:11 PM, Gaetan Rivet wrote: > >> >> > --- a/lib/librte_eal/common/include/rte_bus.h > >> >> > +++ b/lib/librte_eal/common/include/rte_bus.h > >> >> > /** > >> >> > + * Implementation specific probe function which is responsible for linking > >> >> > + * devices on that bus with applicable drivers. > >> >> > + * The plugged device might already have been used previously by the bus, > >> >> > + * in which case some buses might prefer to detect and re-use the relevant > >> >> > + * information pertaining to this device. > >> >> > + * > >> >> > + * @param da > >> >> > + * Device declaration. > >> >> > + * > >> >> > + * @return > >> >> > + * The pointer to a valid rte_device usable by the bus on success. > >> >> > + * NULL on error. rte_errno is then set. > >> >> > + */ > >> >> > +typedef struct rte_device * (*rte_bus_plug_t)(struct rte_devargs *da); > >> >> > >> >> Shouldn't this be orthogonal to unplug() and take a rte_device. You > >> >> should only be able to plug devices that have been found by scan > >> >> before. > >> > > >> > Plugging a device that has been scanned before is a special case. > >> > In a true hotplug scenario, we could use this plug function passing > >> > a devargs. > >> > I don't see any issue passing rte_devargs to plug and rte_device to unplug. > >> > >> What do you mean by "true hotplug"? > > > > I mean a kernel notification of a new device. > > Does a "false hotplug" exist, too? :) The false hotplug was the original attach function which was just adding a new ethdev interface. > >> The problem with this is that passing just rte_devargs to plug() > >> requires the bus to parse and enrich the rte_devargs with bus > >> specifics. From there it gets folded into the to-be-created bus > >> specific rte_XXX_device. This makes it unnecessarily complicated and > >> even worse it adds a second code path how devices come alive. > > > > Just after the notification, the rte_device does not exist yet. > > So the plug function could share the same code as the scan function > > to get the metadata and create the device instance. > > Exactly this is what I want to avoid. Why do you want to avoid that? I think you mean it is not what you had in mind. > The plug() function would become a "scan-one and probe". Yes > From my point of view plug() and unplug() should be orthogonal. > The plug() and unplug() should only be responsible for adding drivers > with optional arguments. The EAL should allow the drivers to get > unplugged/re-plugged at run-time. I want to be able to change arguments > ... or even drivers :) It is a totally different thing. We are talking about hotplug of a device, and you are talking about changing drivers dynamically. So I still don't understand what is the issue with the plug/unplug functions proposed here. > >> When we get notified about a hotplug event we already know which bus > >> this event belongs to: > >> > >> 1. scan the bus for incoming devices > > > > No need to scan every devices here. > > This is a readdir followed by open+read+close for any new device. This > code belongs here anyway. Its lightweight if nothing changed. The scan > itself should be idempotent anyway. > > >> 2. plug single device with devargs and probe for drivers > >> > >> Makes sense? > > > > I want to make sure there is no misunderstanding first :) > > Which makes sense. That is probably my fault due to being too > distracted with other things and not communicating well enough while > Gaetan consumed my code. Your ideas are probably interesting, and I want to understand them. In the meantime, we need to progress on 17.08-rc1 which must be done in following days. Please let's separate the ideas which are not yet implemented from what we are already able to deliver.