Re: [dpdk-dev] [PATCH v6 08/11] eal: pci: introduce RTE_KDRV_VFIO_NOIOMMUi driver mode

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2016-01-21 16:43, Santosh Shukla:
> David Marchand <david.marchand@6wind.com> wrote:
> > This is a mode (specific to vfio), not a new kernel driver.
> >
> Yes, Specific to VFIO and this is why noiommu appended after vfio i.e..
> __VFIO and __VFIO_NOIOMMU.

Woaaa! Your logic is really disappointing :)
Specific to VFIO => append _NOIOMMU
If it's for VFIO, it should be called VFIO (that's my logic).

> > How come we need to distinguish between with/without iommu modes ?
> 
> By default vfio framework assumes iommu i.,e., iommu present. Unless user
> explicitly set "enable_unsafe_noiommu_mode" param. so in my opinion, we
> care to parse vfio driver for _noiommu_ mode only.

Why do we care to parse noiommu only?
Even if virtio cannot work in an IOMMU case, there is no reason to add
a VFIO_NOIOMMU type here.

> > Should not vfio behave the same way from an api point of view ?
> >
> Yes It should. vfio gives similar file_ops i.e.. read/write/mmap/seek etc..
> I am little confused on your question, do you see any issue in vfio bar
> rd/wr api implementation?

I think you should just consider the VFIO API and let the noiommu option
as a kernel configuration detail.