From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [dpdk-dev, RFC] drivers: advertise kmod dependencies in pmdinfo Date: Fri, 02 Sep 2016 12:55:34 +0200 Message-ID: <6075913.EyZdORayqR@xps13> References: <1472217646-26219-1-git-send-email-olivier.matz@6wind.com> <20160901173519.GA11132@hmsreliant.think-freely.org> <20160901104122.41c131be@xeon-e3> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: dev@dpdk.org To: Stephen Hemminger , Neil Horman , "Trahe, Fiona" , Olivier Matz Return-path: Received: from mail-wm0-f54.google.com (mail-wm0-f54.google.com [74.125.82.54]) by dpdk.org (Postfix) with ESMTP id 140963990 for ; Fri, 2 Sep 2016 12:55:37 +0200 (CEST) Received: by mail-wm0-f54.google.com with SMTP id 1so25046900wmz.1 for ; Fri, 02 Sep 2016 03:55:37 -0700 (PDT) In-Reply-To: <20160901104122.41c131be@xeon-e3> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 2016-09-01 10:41, Stephen Hemminger: > Neil Horman wrote: > > On Thu, Sep 01, 2016 at 12:55:27PM +0000, Trahe, Fiona wrote: > > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Olivier Matz > > > > On 08/31/2016 03:27 PM, Neil Horman wrote: > > > > > Oh, I see, so your list is a colon delimited list of module load sets, where at > > > > > least one set must succeed by loading all modules in its set, but the failure of > > > > > any one set isn't fatal to the process? e.g. a string like this: > > > > > > > > > > uio,igb_uio:vfio,vfio-pci > > > > > > > > > > could be interpreted to mean "I must load (uio AND igb_uio) OR (vfio AND > > > > > vfio-pci). If the evaluation of that statement results in false, then the > > > > > operation fails, otherwise it succedes. > > > > > > > > > > If thats the case, then, apologies, we're on the same page, and this will work > > > > > just fine. > > > > > > > > Yep, that's the idea. > > > > > > > > Colon and commas are the best separators I've thought about, but any > > > > idea to make the syntax clearer is welcome ;) > > > > > > > > Maybe a syntax like is clearer: > > > > "(mod1 & mod2)|(mod3 & mod4)" ? > > > > But it would let the user think that more complex expressions are valid, > > > > like "(mod1 & (mod2 | mod3)) | mod4", which is probably overkill. > > > > > > This RFC seems like a good idea - and something the Intel QuickAssist PMD could benefit from. > > > However the (mod1 & mod2) can handle the QAT case better in my opinion. > > > i.e. > > > as well as needing one of > > > * uio igb_uio > > > * uio uio_pci_generic > > > * vfio vfio-pci > > > QAT PMD also needs one of (depending on which physical device is plugged) > > > * qat_dh895xcc > > > * qat_c62x > > > * qat_c3xxx > > > > > > So the original syntax would result in a very long list of possible variations. > > > What really reflects the dependencies would be > > > ((uio & igb_uio) | (uio & uio_pci_generic) | (vfio & vfio_pci)) & (qat_dh895xcc | qat_c62x | qat_c3xxx) > > > > > Ah, I didn't consider that hardware specifics might create a use case where a > > pmd must have one or more kernel modules available for hw support. Perhaps it > > is worthwhile to automate hardware support - that is to say, any module loading > > script should automatically look at the pci table exported from a pmd, and, if > > found, load any modules that claim support for that device:vendor tuple? Though > > that might break in the case of uio, if there are separate driver modules that > > support native hardware and uio access. > > I ended up writing a script that went the other way. > First look at the hardware and load VFIO if IOMMU is available. > Then look for special driver needed for Xen and HyperV > Lastly fallback to loading igb_uio if no VFIO and PCI device present. > > In other words it is a system not driver issue. That's partly right, yes. But you need some information which are specific to the drivers and we should try to embed them for three usages: - give more info the user (without digging in the doc) - replace info in some external system scripts harder to maintain - prepare for hotplug Some PMDs do not use UIO or VFIO at all, However, I agree that the requirement (uio & igb_uio) | (uio & uio_pci_generic) | (vfio & vfio_pci) - and even the VFIO noiommu case - could be translated into a simple flag, let's say "generic_device_mapping" (unfortunately "queue_mapping" doesn't exist). The other interesting point from Fiona is to show that this information is device-related (not general for the whole driver). So we should add a device parameter in the macro with the ability to set a wildcard.