From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Trahe, Fiona" Subject: Re: [dpdk-dev, RFC] drivers: advertise kmod dependencies in pmdinfo Date: Fri, 2 Sep 2016 09:19:26 +0000 Message-ID: <348A99DA5F5B7549AA880327E580B4358909CE45@IRSMSX101.ger.corp.intel.com> References: <1472217646-26219-1-git-send-email-olivier.matz@6wind.com> <20160830132352.GB30977@hmsreliant.think-freely.org> <48f9320b-9402-0ecd-8971-c3785778081a@6wind.com> <20160831132709.GA32000@hmsreliant.think-freely.org> <54a0164e-b242-b930-ec91-60f91b700119@6wind.com> <348A99DA5F5B7549AA880327E580B4358909A43A@IRSMSX101.ger.corp.intel.com> <20160901173519.GA11132@hmsreliant.think-freely.org> <20160901104122.41c131be@xeon-e3> <20160901191538.GB11132@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Cc: "dev@dpdk.org" , Olivier Matz , Thomas Monjalon , "Trahe, Fiona" To: Neil Horman , Stephen Hemminger Return-path: Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by dpdk.org (Postfix) with ESMTP id CFA764CE4 for ; Fri, 2 Sep 2016 11:19:29 +0200 (CEST) In-Reply-To: <20160901191538.GB11132@hmsreliant.think-freely.org> Content-Language: en-US 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" > -----Original Message----- > From: Neil Horman [mailto:nhorman@tuxdriver.com] > Sent: Thursday, September 1, 2016 8:16 PM > To: Stephen Hemminger > Cc: Trahe, Fiona ; dev@dpdk.org; Olivier Matz > ; Thomas Monjalon > > Subject: Re: [dpdk-dev] [dpdk-dev, RFC] drivers: advertise kmod dependenc= ies > in pmdinfo >=20 > On Thu, Sep 01, 2016 at 10:41:22AM -0700, Stephen Hemminger wrote: > > On Thu, 1 Sep 2016 13:35:19 -0400 > > Neil Horman wrote: > > > > > On Thu, Sep 01, 2016 at 12:55:27PM +0000, Trahe, Fiona wrote: > > > > Hi Neil and Olivier, > > > > > > > > > -----Original Message----- > > > > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Olivier > > > > > Matz > > > > > Sent: Wednesday, August 31, 2016 2:40 PM > > > > > To: Neil Horman > > > > > Cc: dev@dpdk.org; thomas.monjalon@6wind.com > > > > > Subject: Re: [dpdk-dev] [dpdk-dev, RFC] drivers: advertise kmod > > > > > dependencies in pmdinfo > > > > > > > > > > Hi Neil, > > > > > > > > > > On 08/31/2016 03:27 PM, Neil Horman wrote: > > > > > > On Wed, Aug 31, 2016 at 11:21:18AM +0200, Olivier Matz wrote: > > > > > >> Hi Neil, > > > > > >> > > > > > >> On 08/30/2016 03:23 PM, Neil Horman wrote: > > > > > >>> On Fri, Aug 26, 2016 at 03:20:46PM +0200, Olivier Matz wrote: > > > > > >>>> Add a new macro DRIVER_REGISTER_KMOD_DEP() that allows a > > > > > >>>> driver to declare the list of kernel modules required to run= properly. > > > > > >>>> > > > > > >>>> Today, most PCI drivers require uio/vfio. > > > > > >>>> > > > > > >>>> Signed-off-by: Olivier Matz > > > > > >>>> > > > > > >>>> --- > > > > > >>>> In this RFC, I supposed that all PCI drivers require a the > > > > > >>>> loading of a uio/vfio module (except mlx*), this may be wron= g. > > > > > >>>> Comments are welcome! > > > > > >>>> > > > > > >>>> > > > > > >>>> buildtools/pmdinfogen/pmdinfogen.c | 1 + > > > > > >>>> buildtools/pmdinfogen/pmdinfogen.h | 1 + > > > > > >>>> drivers/crypto/qat/rte_qat_cryptodev.c | 2 ++ > > > > > >>>> drivers/net/bnx2x/bnx2x_ethdev.c | 4 ++++ > > > > > >>>> drivers/net/bnxt/bnxt_ethdev.c | 2 ++ > > > > > >>>> drivers/net/cxgbe/cxgbe_ethdev.c | 2 ++ > > > > > >>>> drivers/net/e1000/em_ethdev.c | 2 ++ > > > > > >>>> drivers/net/e1000/igb_ethdev.c | 4 ++++ > > > > > >>>> drivers/net/ena/ena_ethdev.c | 2 ++ > > > > > >>>> drivers/net/enic/enic_ethdev.c | 2 ++ > > > > > >>>> drivers/net/fm10k/fm10k_ethdev.c | 2 ++ > > > > > >>>> drivers/net/i40e/i40e_ethdev.c | 2 ++ > > > > > >>>> drivers/net/i40e/i40e_ethdev_vf.c | 2 ++ > > > > > >>>> drivers/net/ixgbe/ixgbe_ethdev.c | 4 ++++ > > > > > >>>> drivers/net/mlx4/mlx4.c | 2 ++ > > > > > >>>> drivers/net/mlx5/mlx5.c | 3 +++ > > > > > >>>> drivers/net/nfp/nfp_net.c | 2 ++ > > > > > >>>> drivers/net/qede/qede_ethdev.c | 4 ++++ > > > > > >>>> drivers/net/szedata2/rte_eth_szedata2.c | 2 ++ > > > > > >>>> drivers/net/thunderx/nicvf_ethdev.c | 2 ++ > > > > > >>>> drivers/net/virtio/virtio_ethdev.c | 2 ++ > > > > > >>>> drivers/net/vmxnet3/vmxnet3_ethdev.c | 2 ++ > > > > > >>>> lib/librte_eal/common/include/rte_dev.h | 14 ++++++++++++++ > > > > > >>>> tools/dpdk-pmdinfo.py | 5 ++++- > > > > > >>>> 24 files changed, 69 insertions(+), 1 deletion(-) > > > > > >>>> > > > > > >>> > > > > > >>> Generally speaking, I like the idea, it makes sense to me in > > > > > >>> terms of using pmdinfo to export this information > > > > > >>> > > > > > >>> That said, This may need to be a set of macros. By that I > > > > > >>> mean (and correct > > > > > me > > > > > >>> if I'm wrong here), but the relationship between pmd's and > > > > > >>> kernel modules > > > > > is in > > > > > >>> some cases, more complex than a 'requires' or 'depends' > > > > > >>> relationship. That > > > > > is > > > > > >>> to say, some pmd may need user space hardware access, but > > > > > >>> can use either > > > > > uio OR > > > > > >>> vfio, but doesn't need both, and can continue to function if > > > > > >>> only one is available. Other PMD's may be able to use vfio > > > > > >>> or uio, but can still function without either. And some, as > > > > > >>> your patch implements, simply require one or > > > > > the > > > > > >>> other to function. As such it seems like you may want a few > > > > > >>> macros, in the > > > > > form > > > > > >>> of: > > > > > >>> > > > > > >>> DRIVER_REGISTER_KMOD_REQUEST - List of modules to attempt > > > > > >>> loading, > > > > > ignore any > > > > > >>> failures > > > > > >>> DRIVER_REGISTER_KMOD_REQUIRE - List of modules required to > > > > > >>> be > > > > > loaded after > > > > > >>> request macro completes, fail if any are not loaded > > > > > >>> > > > > > >>> Thats just spitballing, mind you, theres probably a better > > > > > >>> way to do it, but > > > > > the > > > > > >>> idea is to list a set of modules you would like to have, and > > > > > >>> then create a parsable syntax to describe the modules that > > > > > >>> need to be loaded after the > > > > > request > > > > > >>> is complete so that you can accurately codify the situations > > > > > >>> I described > > > > > above. > > > > > >> > > > > > >> Thank you for your feedback. > > > > > >> However, I'm not sure I'm perfectly getting what you suggest. > > > > > >> > > > > > >> Do you think some PMDs could request a kernel module without > > > > > >> really requiring it? Do you have an example in mind? > > > > > >> > > > > > > Yes, thats precisely it. The most clear example I could think > > > > > > of (though I'm not sure if any pmd currently supports this), > > > > > > is a pmd that supports both UIO and VFIO communication with > > > > > > the kernel. Such a PMD requires that one of > > > > > those > > > > > > two modules be loaded, but only one (i.e. both are not > > > > > > required), so if only > > > > > the > > > > > > uio kernel module loads is a success case, likewise if only > > > > > > the vfio module loads can be treated as success. Both loading > > > > > > are clearly successful. Only if neither load do we have a > > > > > > failure case. I'm suggesting that the grammer that your > > > > > > exports define should take those cases into account. Its not a= lways as > simple as "I must have the following modules" > > > > > > > > > > > >> The syntax I've submitted lets you define several lists of > > > > > >> modules, so that the user or the script that starts the > > > > > >> application can decide which kmod list is better according to = the > environment. > > > > > >> > > > > > > If you have a human intervening in the module load process, > > > > > > sure, then its > > > > > fine. > > > > > > But it seems that this particular feature that you're > > > > > > implemnting might have automated uses. That is to say the > > > > > > dpdk core library might be interested in parsing this > > > > > > particular information to direct module autoloading, and if > > > > > > thats desireable then you need to define these lists such that = you can > codify failure and success conditions. > > > > > > > > > > > >> For example, most drivers will advertise > > > > > >> "uio,igb_uio:uio,uio_pci_generic:vfio,vfio-pci", and the user > > > > > >> or script will have to choose between loading: > > > > > >> - uio igb_uio > > > > > >> - uio uio_pci_generic > > > > > >> - vfio vfio-pci > > > > > >> > > > > > > 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 succed= es. > > > > > > > > > > > > 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 probabl= y > overkill. > > > > > > > > > > Regards, > > > > > Olivier > > > > > > > > This RFC seems like a good idea - and something the Intel QuickAssi= st 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 mod= ules that > support native hardware and uio access. Actually if the script output was intended to be used to auto-load dependen= t kmods,=20 then even the above would not suffice for the QAT driver (and presumably fo= r other PMDs with specific HW dependencies). i.e. the qat_dhxxxx modules have furth= er dependencies=20 themselves on an intel_qat module, and there are other steps documented in = the=20 guide which must be taken after loading the kmods.=20 The use-case I'd addressed was for the script to identify and just throw an= error where=20 dependent modules are missing.=20 I don't see a simple solution, but also don't see a strong need to find one= .=20 Documentation and if necessary a driver-specific script seem sufficient to = me. My conclusion is the RFC is a nice feature for some drivers, but if introdu= ced needs=20 to be optional as it doesn't handle the complexities of all drivers.=20 > > > > 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 sounds like a reasonable approach, yes. > Neil >=20 > >