-----Original Message----- > Date: Tue, 4 Sep 2018 23:40:36 -0400 > From: Eric Zhang <eric.zh...@windriver.com> > To: santosh <santosh.shu...@caviumnetworks.com>, hemant.agra...@nxp.com, > Gaëtan Rivet <gaetan.ri...@6wind.com>, "Burakov, Anatoly" > <anatoly.bura...@intel.com> > CC: bruce.richard...@intel.com, dev@dpdk.org, allain.leg...@windriver.com, > matt.pet...@windriver.com > Subject: Re: [dpdk-dev] [PATCH] eal: force IOVA mode to physical > User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 > Thunderbird/52.9.1 > > On 08/30/2018 08:59 AM, santosh wrote: > > On Thursday 30 August 2018 05:43 PM, Hemant wrote: > > > External Email > > > > > > Hi, > > > > > > On 8/30/2018 3:13 PM, Gaëtan Rivet wrote: > > > > Hi, > > > > > > > > On Thu, Aug 30, 2018 at 10:09:04AM +0100, Burakov, Anatoly wrote: > > > > > On 29-Aug-18 4:58 PM, eric zhang wrote: > > > > > > This patch adds a configuration option to force the IOVA mode to > > > > > > physical address (PA). There exists virtual devices that are not > > > > > > directly attached to the PCI bus, and therefore the auto detection > > > > > > of the IOVA mode based on probing the PCI bus and IOMMU > > > > > > configuration > > > > > > may not report the required addressing mode. Having the > > > > > > configuration > > > > > > option permits the mode to be explicitly configured in this > > > > > > scenario. > > > > > > > > > > > > Signed-off-by: eric zhang <eric.zh...@windriver.com> > > > > > > --- > > > > > Defining this at compile-time seems like an overkill. Wouldn't it be > > > > > better > > > > > to just add an EAL command-line option to force IOVA mode to a > > > > > particular > > > > > value? > > > That is a good suggestion. > > > > > -- > > > > > Thanks, > > > > > Anatoly > > > > What is the bus of these devices and why not implement get_iommu_class > > > > in it? > > > There are cases, where you are using dpdk libraries with external > > > libraries and you need to change the default behavior DPDK lib to use > > > physical address instead of virtual address. > > > Providing an option to user will help. > > > > > > > > More appropriate solution could be: > > * Either fix it at bus layer .. i.e.. get_iommu_class().. > > * Or introduce something like [1] --iova-mode=<pa/va> param. > > > > Former is better solution than latter if autodetection is a key criteria. > > Thanks. > > > > [1] http://patchwork.dpdk.org/patch/25192/ > > > It's not generic which couldn't be fixed at bus layer. > So what's the preference of EAL option or compile time solution? > Adding --iova-mode as patch [1] will overrivde auto-detection > rte_bus_get_iommu_class() > make it no use; compile time solution will align with upstream and keep > new atuodetection > solution in #ifndef.
If it is for vdev devices, why not introduce something like RTE_PCI_DRV_IOVA_AS_VA and let vdev device describe its personality. And based on the devices(flags) on vdev bus, rte_bus_get_iommu_class() of vdev can decide the mode just like PCI bus. > > Thanks > Eric >
