From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?iso-8859-1?Q?Ga=EBtan?= Rivet Subject: Re: [PATCH] bus/pci: fix vfio mode Date: Mon, 30 Oct 2017 18:13:50 +0100 Message-ID: <20171030171349.GI10890@bidouze.vm.6wind.com> References: <20171028062053.6615-1-jerin.jacob@caviumnetworks.com> <20171030091736.GH10890@bidouze.vm.6wind.com> <3786691.UAh344p4j6@xps> <1799529.Vp2fhR3gtB@xps> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: Thomas Monjalon , dev@dpdk.org, Jerin Jacob To: Ferruh Yigit Return-path: Received: from mail-wm0-f65.google.com (mail-wm0-f65.google.com [74.125.82.65]) by dpdk.org (Postfix) with ESMTP id 95590199B5 for ; Mon, 30 Oct 2017 18:14:03 +0100 (CET) Received: by mail-wm0-f65.google.com with SMTP id r196so17942580wmf.2 for ; Mon, 30 Oct 2017 10:14:03 -0700 (PDT) Content-Disposition: inline In-Reply-To: List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Mon, Oct 30, 2017 at 09:57:08AM -0700, Ferruh Yigit wrote: > On 10/30/2017 4:24 AM, Thomas Monjalon wrote: > > 30/10/2017 10:27, Thomas Monjalon: > >> 30/10/2017 10:17, Gaëtan Rivet: > >>> Hi Ferruh, > >>> > >>> On Mon, Oct 30, 2017 at 02:00:43AM -0700, Ferruh Yigit wrote: > >>>> On 10/30/2017 1:06 AM, Gaëtan Rivet wrote: > >>>>> Hi Jerin, > >>>>> > >>>>> On Sat, Oct 28, 2017 at 11:50:52AM +0530, Jerin Jacob wrote: > >>>>>> The definition of VFIO_PRESENT is "eal_vfio.h", Fail to > >>>>>> include eal_vfio.h will result in disabling vfio. > >>>>>> > >>>>>> Fixes: 279b581c897d ("vfio: expose functions") > >>>>>> > >>>>> > >>>>> Thanks for the fix, sorry for VFIO. > >>>>> I tried to let go of VFIO_PRESENT in the PCI patchset, unfortunately I did > >>>>> not do a good-enough job. > >>>>> > >>>>> Instead of reinstating the dependency on the private eal_vfio.h header, > >>>>> I'd suggest replacing all VFIO_PRESENT references within the PCI bus by > >>>>> RTE_EAL_VFIO, and make the pci_vfio.c compilation depend on it within > >>>>> the linux Makefile. Something like: > >>>>> > >>>>> ---8<--- > >>>>> > >>>>> grep -rl VFIO_PRESENT drivers/bus/pci/linux/ |while read -r file > >>>>> do sed -i 's;VFIO_PRESENT;RTE_EAL_VFIO;' $file > >>>>> done > >>>> > >>>> VFIO_PRESENT is the combination of the if user enabled VFIO and if Linux kernel > >>>> supports it. > >>>> > >>>> Why not add same check and VFIO_PRESENT definition to rte_vfio.h: > >>>> > >>>> --- a/lib/librte_eal/common/include/rte_vfio.h > >>>> +++ b/lib/librte_eal/common/include/rte_vfio.h > >>>> @@ -34,7 +34,13 @@ > >>>> #ifndef _RTE_VFIO_H_ > >>>> #define _RTE_VFIO_H_ > >>>> > >>>> +#if !defined(VFIO_PRESENT) && defined(RTE_EAL_VFIO) > >>>> +#include > >>>> +#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 6, 0) > >>>> #include > >>>> +#define VFIO_PRESENT > >>>> +#endif /* >= 3.6.0 */ > >>>> +#endif > >>>> + > >>>> +#ifdef VFIO_PRESENT > >>>> > >>>> ... Need to wrap here in case VFIO disabled ... > >>>> > >>>> #endif > >>>> > >>> > >>> It would work indeed. > >>> > >>> I mostly dislike having whole compilation units disabled silently on a > >>> linux version check. I think that if someone wanted to support kernels < > >>> 3.6, they ought to do the work of disabling RTE_EAL_VFIO. > >>> > >>> A build error could be thrown to help those users toward the right > >>> solution, but I think that the meaning of having this option enabled > >>> should be enforced: if it is enabled, it is compiled. If dependencies > >>> are not met, then the option should be disabled. > >> > >> +1 to avoid implicit disabling. > > > > To make it clear, we can disable VFIO automatically if not supported by > > the kernel at compilation time, but there should be a warning. > > Gaetan suggest letting build error and push user to disable the feature. If we > let the build error, I think feature should be disabled by default. > > And for VFIO, instead of disabling it by default I am for auto disable it if > kernel requirement not met, and +1 for adding a warning. > > btw, that kernel version check is already in eal_vfio.h, we are already > disabling some vfio code based on kernel version check, weather add here or not. > > Thanks, > ferruh The new version of the patches should behave like you described :) . I still think VFIO_PRESENT should be changed, but not now. -- Gaëtan Rivet 6WIND