Re: [dpdk-dev] [EXT] Re: [PATCH v2 4/4] eal: select IOVA mode as VA for default case

[Jerin Jacob Kollanukkaran <jerinj@marvell.com>]

> >>>      Addresses, then EAL init will fail early, since later probing of the
> devices
> >>>      would fail anyway,
> >>> -- if the preferred mode is RTE_IOVA_DC then based on the Physical
> >>> Addresses
> >>> -  availability, the preferred mode is adjusted to RTE_IOVA_PA or
> >> RTE_IOVA_VA.
> >>> +- if the preferred mode is RTE_IOVA_DC then select the IOVA mode as
> >> RTE_IOVA_VA.
> >>> +  The RTE_IOVA_VA selected as the default because,
> >>> +
> >>> +#. All drivers work in RTE_IOVA_VA mode, irrespective of physical
> >>> +address
> >> availability.
> >>
> >> Is there anywhere we can document that any new driver must support
> >> both before being accepted?
> >
> > Not sure why new drivers need to support both PA and VA. Do you mean
> VA?
> > And not sure where to document this as well if need.
> 
> We have a flaf that indicates that the driver needs IOVA as VA. Absence of
> said flag indicates that it supports both IOVA as VA and IOVA as PA.
> So, absent of this flag, any new driver must support both PA and VA, must it
> not?

OK. I will add the following as "note" after "IOVA Mode Detection" section.
I don’t any other place to put this info in the doc. If any change needed
then let me know.

.. note::

    If the device driver needs IOVA as VA and it cannot work with IOVA as PA
    then the driver must request the PCI bus layer using  ``RTE_PCI_DRV_NEED_IOVA_AS_VA``
    requirement flag. Absence of this flag, dictates, the driver must support both IOVA as PA and VA modes.