Re: [dpdk-dev] [PATCH v3] drivers: advertise kmod dependencies in pmdinfo

[Neil Horman <nhorman@tuxdriver.com>]

On Fri, Dec 16, 2016 at 02:19:59PM +0000, Ferruh Yigit wrote:
> On 12/16/2016 12:37 PM, Neil Horman wrote:
> > On Fri, Dec 16, 2016 at 10:22:08AM +0100, Olivier Matz wrote:
> >> Hi,
> >>
> >> On Thu, 15 Dec 2016 09:22:07 -0800, Stephen Hemminger
> >> <stephen@networkplumber.org> wrote:
> >>> On Thu, 15 Dec 2016 11:09:12 -0500
> >>> Neil Horman <nhorman@tuxdriver.com> wrote:
> >>>
> >>>> On Thu, Dec 15, 2016 at 02:46:39PM +0100, Olivier Matz wrote:  
> >>>>> Add a new macro RTE_PMD_REGISTER_KMOD_DEP() that allows a driver
> >>>>> to declare the list of kernel modules required to run properly.
> >>>>>
> >>>>> Today, most PCI drivers require uio/vfio.
> >>>>>
> >>>>> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> >>>>> Acked-by: Fiona Trahe <fiona.trahe@intel.com>
> >>>>> ---
> >>>>>
> >>>>> v2 -> v3:
> >>>>> - fix kmods deps advertised by mellanox drivers as pointed out
> >>>>>   by Adrien
> >>>>>
> >>>>> v1 ->
> >>>>> v2:                                                                                                
> >>>>> - do not advertise uio_pci_generic for vf drivers
> >>>>> - rebase on top of head: use new driver names and prefix
> >>>>>   macro with
> >>>>> RTE_                                                                                       
> >>>>>
> >>>>> rfc -> v1:
> >>>>> - the kmod information can be per-device using a modalias-like
> >>>>>   pattern
> >>>>> - change syntax to use '&' and '|' instead of ',' and ':'
> >>>>> - remove useless prerequisites in kmod lis: no need to
> >>>>>   specify both uio and uio_pci_generic, only the latter is
> >>>>>   required
> >>>>> - update kmod list in szedata2 driver
> >>>>> - remove kmod list in qat driver: it requires more than just
> >>>>> loading a kmod, which is described in documentation
> >>>>>
> >>>>>  buildtools/pmdinfogen/pmdinfogen.c      |  1 +
> >>>>>  buildtools/pmdinfogen/pmdinfogen.h      |  1 +
> >>>>>  drivers/net/bnx2x/bnx2x_ethdev.c        |  2 ++
> >>>>>  drivers/net/bnxt/bnxt_ethdev.c          |  1 +
> >>>>>  drivers/net/cxgbe/cxgbe_ethdev.c        |  1 +
> >>>>>  drivers/net/e1000/em_ethdev.c           |  1 +
> >>>>>  drivers/net/e1000/igb_ethdev.c          |  2 ++
> >>>>>  drivers/net/ena/ena_ethdev.c            |  1 +
> >>>>>  drivers/net/enic/enic_ethdev.c          |  1 +
> >>>>>  drivers/net/fm10k/fm10k_ethdev.c        |  1 +
> >>>>>  drivers/net/i40e/i40e_ethdev.c          |  1 +
> >>>>>  drivers/net/i40e/i40e_ethdev_vf.c       |  1 +
> >>>>>  drivers/net/ixgbe/ixgbe_ethdev.c        |  2 ++
> >>>>>  drivers/net/mlx4/mlx4.c                 |  2 ++
> >>>>>  drivers/net/mlx5/mlx5.c                 |  1 +
> >>>>>  drivers/net/nfp/nfp_net.c               |  1 +
> >>>>>  drivers/net/qede/qede_ethdev.c          |  2 ++
> >>>>>  drivers/net/szedata2/rte_eth_szedata2.c |  2 ++
> >>>>>  drivers/net/thunderx/nicvf_ethdev.c     |  1 +
> >>>>>  drivers/net/virtio/virtio_ethdev.c      |  1 +
> >>>>>  drivers/net/vmxnet3/vmxnet3_ethdev.c    |  1 +
> >>>>>  lib/librte_eal/common/include/rte_dev.h | 25
> >>>>> +++++++++++++++++++++++++ tools/dpdk-pmdinfo.py
> >>>>> |  5 ++++- 23 files changed, 56 insertions(+), 1 deletion(-)
> >>>>>     
> >>>> Its odd that all devices, regardless of vendor should depend on the
> >>>> igb_uio module.  It seems to me that depending on uio_pci_generic
> >>>> or vfio is sufficient.
> >>
> >> igb_uio is the historical uio module of dpdk. Although it is called
> >> igb_uio, it is not specific to Intel drivers.
> >>
> >> Most drivers declare "igb_uio | uio_pci_generic | vfio", which means
> >> that any of the 3 kernel modules can be used.
> >>
> >> I think there are some cases where people will prefer using igb_uio,
> >> for instance to use a vf pmd in a vm where there is no iommu,
> >> and where the kernel vfio module does not support the no-iommu mode.
> >>
> >>
> >>>
> >>> Yes it seems just a special case extension for Mellanox drivers.
> >>
> >> Kmod deps are different whether it's a vf driver or not.
> >> Mellanox drivers are not the only drivers that do not require uio,
> >> there is also szedata2.
> >>
> >> Is it an argument for not including this patch?
> >>
> > Speaking only for myself, I'm not suggesting the patch not be included, only
> > questioning the need to list igb_uio as an optional dependency.  From what I
> > understand uio_pci_generic is equaly capable of being used in a vf as igb_uio,
> > and so it seems like its sufficient to list in the deps alone, or am I missing
> > something?
> > 
> > Additionally, in regards to the comment about rebasing on net-next here, I don't
> > think thats needed.  This patch is built such that you will be able to apply
> > this tag to additional drivers later, as they get merged into thomas's tree, you
> > don't need to get them all in one shot.
> 
> Right, more drivers can be added later. But also I don't see any problem
> if this patch rebased on next-net and be a more complete patch. That is
> why it was a question to the author.
> 
Right, it certainly doesn't hurt anything to do so, but given that:

1) We're on v3 of this patch
2) Not including information in all drivers isn't catastrophic
3) Rebasing on net-next still leaves the crypto drivers unaccounted for

It seems to me that including the patch now, so that the infrastructure is in
place for driver maintainers to add the macro on their own in their respective
trees seems like the more expiedient course of action.

Best
Neil