[dpdk-dev] [PATCH v10 3/9] linuxapp/eal_pci: get iommu class

[santosh]

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.

Thanks.