On Wednesday 11 October 2017 12:34 PM, Tan, Jianfeng wrote: > >> -----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)?
Right, same I proposed (I guess) in v2 such that iova bus autodetecting in case see all device bound to vfio-pci then autoselect iova=va, in v3 series (I guess) discussion: it was concluded that better to send hint from driver. Refer work history, though iova bus still does said auto-detection. Thanks.
