RE: [PATCH v12 04/16] baseband/acc: introduce PMD for ACC200

["Chautru, Nicolas" <nicolas.chautru@intel.com>]

Hi Thomas, 

> -----Original Message-----
> From: Thomas Monjalon <thomas@monjalon.net>
> 31/10/2022 16:43, Chautru, Nicolas:
> > From: Thomas Monjalon <thomas@monjalon.net>
> > > 12/10/2022 19:59, Nicolas Chautru:
> > > > +Bind PF UIO driver(s)
> > > > +~~~~~~~~~~~~~~~~~~~~~
> > > > +
> > > > +Install the DPDK igb_uio driver, bind it with the PF PCI device
> > > > +ID and use ``lspci`` to confirm the PF device is under use by
> > > > +``igb_uio`` DPDK
> > > UIO driver.
> > >
> > > igb_uio is not recommended.
> > > Please focus on VFIO first.
> > >
> > > > +The igb_uio driver may be bound to the PF PCI device using one of
> > > > +two methods for ACC200:
> > > > +
> > > > +
> > > > +1. PCI functions (physical or virtual, depending on the use case)
> > > > +can be bound to the UIO driver by repeating this command for every
> function.
> > > > +
> > > > +.. code-block:: console
> > > > +
> > > > +  cd <dpdk-top-level-directory>
> > > > +  insmod ./build/kmod/igb_uio.ko
> > > > +  echo "8086 57c0" > /sys/bus/pci/drivers/igb_uio/new_id
> > > > +  lspci -vd8086:57c0
> > > > +
> > > > +
> > > > +2. Another way to bind PF with DPDK UIO driver is by using the
> > > > +``dpdk-devbind.py`` tool
> > > > +
> > > > +.. code-block:: console
> > > > +
> > > > +  cd <dpdk-top-level-directory>
> > > > +  ./usertools/dpdk-devbind.py -b igb_uio 0000:f7:00.0
> > > > +
> > > > +where the PCI device ID (example: 0000:f7:00.0) is obtained using
> > > > +lspci -vd8086:57c0
> > >
> > > This binding is not specific to the driver.
> > > It would be better to refer to the Linux guide instead of
> > > duplicating it again and again.
> > >
> > > > +In a similar way the PF may be bound with vfio-pci as any PCIe device.
> > >
> > > You could mention igb_uio here.
> > > Is there any advantage in using igb_uio?
> > >
> >
> > Igb_uio is arguably easier to use to new user tend to start with it or specific
> ecosystem. This is typically the entry point (no iommu, no flr below the bonnet,
> no vfio token...) hence good to have a bit of handholding with a couple of lines
> capturing how to easily run a few tests. I don't believe this is too redundant to
> have these few lines compared to the help in bring to the user not having to
> double guess their steps.
> > More generally there are a number of module drivers combinations that are
> supported based on different deployments. We don't document in too much
> details for the details since that is not too ACC specific and there is more
> documentation no pf_bb_config repo for using the PMD from the VF..
> >
> > Basically Thomas let us know more explicitly what you are suggesting as
> documentation update. You just want more emphasis on vfio-pci flow (which is
> fair, some of it documented on pf_bb_config including the vfio token passing
> but we can reproduce here as well) or something else?
> 
> There are 2 things to change:
> 1/ igb_uio is going to be deprecated, so we must emphasize on VFIO

Is there a date for deprecation? Do you mean to EOL the dpdk-kmods repository itself; or something more specific for DPDK code like removing RTE_PCI_KDRV_IGB_UIO; or last to just take out from documentation?
It tends to be historical but uio has value notably for ease of use. 

2/ for doc
> maintenance, it is better to have common steps described in one place.
> If needed, you can change the common doc and refer to it.

Do you mean to remove these sections and just add a pointer to https://doc.dpdk.org/guides/linux_gsg/linux_drivers.html instead in all these bbdev PMDS?
Please kindly confirm. I see specific steps for binding in many other PMDs docs in DPDK, a bit redundant but provides simple steps specific to a PMD in one place. I don't mind either way. 

Thanks
Nic