From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ferruh Yigit Subject: Re: [PATCH] bus/pci: fix vfio mode Date: Mon, 30 Oct 2017 09:57:08 -0700 Message-ID: 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=utf-8 Content-Transfer-Encoding: 8bit Cc: dev@dpdk.org, Jerin Jacob To: Thomas Monjalon , =?UTF-8?Q?Ga=c3=abtan_Rivet?= Return-path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id EAE601B2A3 for ; Mon, 30 Oct 2017 17:57:12 +0100 (CET) In-Reply-To: <1799529.Vp2fhR3gtB@xps> Content-Language: en-US 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 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