[dpdk-dev] [PATCH v5 1/4] examples/multi_process/client_server_mp: check port validity

[Matan Azrad]

From: Stephen Hemminger
> On Wed, 7 Aug 2019 05:38:42 +0000
> Matan Azrad <matan at mellanox.com> wrote:
> 
> > From: Stephen Hemminger
> > > Sent: Wednesday, August 7, 2019 2:09 AM
> > > To: Matan Azrad <matan at mellanox.com>
> > > Cc: dev at dpdk.org; Stephen Hemminger <sthemmin at microsoft.com>
> > > Subject: Re: [dpdk-dev] [PATCH v5 1/4]
> > > examples/multi_process/client_server_mp: check port validity
> > >
> > > On Tue, 6 Aug 2019 20:03:22 +0000
> > > Matan Azrad <matan at mellanox.com> wrote:
> > >
> > > > >
> > > > > The DPDK has lots of hard coded assumptions of all ports fitting in 64
> bits.
> > > > > Examples include testpmd/parameters.c etc.
> > > >
> > > > Yes, I understand, but the user should know not to change the
> > > > default value of RTE_MAX_ETHPORTS, at least it should be
> documented.
> > > >
> > > > > The original concept of a small set of assigned values for
> > > > > portid is not going to scale. It really should have been more
> > > > > like ifindex; something that is not used by common API's much
> > > > > larger range; and
> > > assigned purely sequentially.
> > > > >
> > > > > The API's should all be using names, but the DPDK port naming is
> > > > > also a mess...
> > > >
> > > > Port ID is OK, user can run port info, then to find the wanted
> > > > port ID and
> > > configure it by port id list\bitmap.
> > > >
> > >
> > >
> > > The examples are toy programs. If user changes RTE_MAX_ETHPORTS it
> > > will break lots of other places. Why put more checks in the
> > > examples. Sorry, it really would not help to pretend that fixing the
> example is going to help this.
> >
> >
> > Agree that it is not needed to fix all the places now.
> > It is better just to update the example documentation that
> RTE_MAX_ETHPORTS must not be changed when running this application.
> >
> > I will ack your series(v7) , Consider to update the doc if you want to be
> completely perfect here.
> 
> Perhaps the right place to tell the users is somewhere in the documentation?
> 
> One place would be here:
> 
> diff --git a/doc/guides/faq/faq.rst b/doc/guides/faq/faq.rst index
> f19c1389b6af..a847d9ceda22 100644
> --- a/doc/guides/faq/faq.rst
> +++ b/doc/guides/faq/faq.rst
> @@ -195,3 +195,8 @@ Why can't my application receive packets on my
> system with UEFI Secure Boot enab
> 
>  If UEFI secure boot is enabled, the Linux kernel may disallow the use of UIO
> on the system.
>  Therefore, devices for use by DPDK should be bound to the ``vfio-pci``
> kernel module rather than ``igb_uio`` or ``uio_pci_generic``.
> +
> +What is the maximum number of ethernet devices?
> +-----------------------------------------------
> +
> +The limit on the number of Ethernet devices is controlled by the
> RTE_MAX_ETHPORTS configuration setting. Since many of the applications
> use a 64 bit value for port mask; the current upper limit is 64 ports.
> 
I think there are systems with a lot of virtual ports which may use more than 64.

So update all the docs when the mask is defined, would be option too.