> -----Original Message----- > From: santosh [mailto:santosh.shu...@caviumnetworks.com] > Sent: Wednesday, October 11, 2017 1:38 PM > To: Tan, Jianfeng; olivier.m...@6wind.com; dev@dpdk.org > Cc: tho...@monjalon.net; jerin.ja...@caviumnetworks.com; > hemant.agra...@nxp.com; acon...@redhat.com; > step...@networkplumber.org; Burakov, Anatoly; gaetan.ri...@6wind.com; > shreyansh.j...@nxp.com; Richardson, Bruce; Gonzalez Monroy, Sergio; > maxime.coque...@redhat.com > Subject: Re: [dpdk-dev] [PATCH v10 3/9] linuxapp/eal_pci: get iommu class > > > On Wednesday 11 October 2017 11:01 AM, Tan, Jianfeng wrote: > > > > > > On 10/11/2017 12:43 PM, santosh wrote: > >> On Wednesday 11 October 2017 07:17 AM, Tan, Jianfeng wrote: > >>> Hi, > >>> > >>> Nice patch series. But I still have a small question about below flag. > >>> > >>> > >>> On 10/6/2017 7:03 PM, Santosh Shukla wrote: > >>>> Get iommu class of PCI device on the bus and returns preferred iova > >>>> mapping mode for that bus. > >>>> > >>>> Patch also introduces RTE_PCI_DRV_IOVA_AS_VA drv flag. > >>>> Flag used when driver needs to operate in iova=va mode. > >>>> > >>> Does this flag indicate a must to use VA as IOVA, or a nice-to-have one? > In detail, above commit log says, "needs to operate in iova=va mode", but > the comment in the patch indicates this flag means "driver supports IOVA as > VA". > >>> > >>> If it's the latter case, I would suppose all drivers support to use VA as > IOVA, if the NICs are binded to vfio-pci (iommu mode). Please correct me if > I'm wrong. > >>> > >> - Any iommu backed pmd could choose to use this flag. > > > > But if this is characterized by assumption for all PMDs, why do we trouble > to introduce this flag. > > > to hint bus layer about iova=va mapping choice for _this_ driver and default > is iova=pa. >
So that sounds if this flag is set by some PMD, we must use iova=va. Then how about we enable this, iova=va, if only all PCI devices are binded to vfio-pci (iommu mode)? Thanks, Jianfeng
