From: Adrien Mazarguil <adrien.mazarguil@6wind.com>
To: Yuanhan Liu <yliu@fridaylinux.org>
Cc: "Gaëtan Rivet" <gaetan.rivet@6wind.com>,
"Thomas Monjalon" <thomas@monjalon.net>,
"Stephen Hemminger" <stephen@networkplumber.org>,
dev@dpdk.org, "Ciara Loftus" <ciara.loftus@intel.com>,
"Kevin Traynor" <ktraynor@redhat.com>,
hemant.agrawal@nxp.com
Subject: Re: [dpdk-dev] [PATCH] [RFC] ether: standardize getting the port by name
Date: Tue, 5 Dec 2017 12:04:46 +0100 [thread overview]
Message-ID: <20171205110446.GN4062@6wind.com> (raw)
In-Reply-To: <20171204135531.GB13614@yliu-dev>
Hi Yuanhan,
On Mon, Dec 04, 2017 at 09:55:31PM +0800, Yuanhan Liu wrote:
> On Fri, Dec 01, 2017 at 10:47:50AM +0100, Gaëtan Rivet wrote:
> > On Thu, Nov 30, 2017 at 10:44:58PM +0100, Thomas Monjalon wrote:
> > > 30/11/2017 22:21, Stephen Hemminger:
> > > > On Thu, 30 Nov 2017 18:35:11 +0100
> > > > Thomas Monjalon <thomas@monjalon.net> wrote:
> > > >
> > > > > 30/11/2017 18:15, Stephen Hemminger:
> > > > > > Some thoughts.
> > > > > > 1) Not all devices are PCI; look at recent VMBUS
> > > > >
> > > > > Yes, we need a syntax which works for every devices.
> > > > > I suggest to use the prefix "pci:" before the PCI id.
> > > > > We need also a prefix and ids for NXP buses.
> > > > > We could use "vmbus:" before VMBUS ids.
> > > > > How VMBUS ids look like?
> > > > >
> >
> > rte_devargs are easily accessible, user-readable. Only thing missing
> > would be requiring a 1-1 mapping between an rte_devargs and a port, thus
> > requiring PMDs to have at least one version of a device string that
> > would probe a single port (as is done with port= in mlx4).
> >
> > Implementing an rte_devargs to rte_device in rte_bus is simple enough,
> > and this would allow implementing an rte_devargs to port_id in rte_eth.
> >
> > What am I missing?
>
> rte_devargs is identified by the name (pci id for pci device). It also
> includes other driver specific key-value options. It's not clear for the
> user to know which one (or few) of them should be used together with the
> PCI id to identify a specific port. For example, as you mentioned, in
> mlx4, it's "pci_id,port=x". It could be something else in other drivers.
Just for information, this "port=x" argument in mlx4 is consistent with the
value found in /sys/class/net/ethX/dev_port under Linux. If we choose to use
a port index (instead of a MAC or something else), it would make sense to
standardize it on the same order as given by the host OS for consistency
across all PMDs.
Devices with a single port per PCI address would simply use/allow "0".
> Actually, this patch also proposes a devarg like naming style: "name[,mac]".
> What it does try to do is to define a standard syntax, so that the user
> doesn't have to know any driver specific options.
>
> However, the mac address is changeable, leaving this naming inconsistent.
> Well, in practice, PCI id is also changeable.
>
> OTOH, having a consistent naming seems a bit far away from this patch's
> goal: define a standard ethdev naming and leave less harassment to the users.
I'm not a fan of the MAC naming scheme either, a kind of per-device physical
port index seems more robust and doesn't require much initialization to
determine how many ports are supported by the device and whether the index is
known/valid (particularly given the vast majority exposes only one per bus
address).
Would it make sense to have this name usable unmodified as a valid device
(-w) argument, including parameters?
If so, PMDs could append parameters while probing the underlying device, by
appending ",port=x", ",mac=x" followed by other unspecified parameters with
default values. This could uniquely identify the port _and_ its
configuration in a reusable fashion.
Otherwise if all we need is unique names, we can use the opposite and much
simpler approach. Let librte_ether assign them sequentially
(e.g. "rte_eth%d", no need for consistency with OS netdevices), applications
can figure the rest based on data structures if needed.
Thoughts?
> > > > > > 2) The name may have to be set before MAC address is determined on boot.
> > > > >
> > > > > I don't understand this comment.
> > > > > Do you mean MAC may be unknown when starting DPDK?
> > > >
> > > > The MAC be known by the hardware, but the device would have to be
> > > > created before using hardware to read it.
> > >
> > > Indeed, it is a problem if we want to use this syntax for blacklist.
> > >
> > >
> > > > > > 3) The names themselves are not persistent or human friendly. This is hard
> > > > > > see the effort udev goes to.
> > > > >
> > > > > Yes udev has a syntax to identify devices. It can be inspiring.
> > > > > Qemu may also be inspiring:
> > > > > https://github.com/qemu/qemu/blob/master/docs/qdev-device-use.txt
--
Adrien Mazarguil
6WIND
next prev parent reply other threads:[~2017-12-05 11:04 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-30 7:35 Yuanhan Liu
2017-11-30 17:15 ` Stephen Hemminger
2017-11-30 17:35 ` Thomas Monjalon
2017-11-30 21:21 ` Stephen Hemminger
2017-11-30 21:44 ` Thomas Monjalon
2017-12-01 9:47 ` Gaëtan Rivet
2017-12-04 13:55 ` Yuanhan Liu
2017-12-05 11:04 ` Adrien Mazarguil [this message]
2017-12-05 13:20 ` Thomas Monjalon
2017-12-05 13:58 ` Yuanhan Liu
2017-12-05 15:28 ` Thomas Monjalon
2017-12-05 17:22 ` Adrien Mazarguil
2017-12-06 15:49 ` Yuanhan Liu
2017-12-18 22:25 ` Thomas Monjalon
2017-12-18 22:30 ` Stephen Hemminger
2017-12-18 22:41 ` Thomas Monjalon
2017-12-18 23:05 ` Thomas Monjalon
2017-12-20 22:02 ` [dpdk-dev] standardize device identification Thomas Monjalon
2017-12-22 7:01 ` Shreyansh Jain
2017-12-22 9:00 ` Thomas Monjalon
2018-01-05 7:52 ` Finn Christensen
2018-01-05 8:39 ` Thomas Monjalon
2018-01-05 11:09 ` Finn Christensen
2018-01-05 12:01 ` Thomas Monjalon
2018-01-05 14:14 ` Finn Christensen
2018-01-05 15:34 ` Thomas Monjalon
2018-01-05 20:32 ` Finn Christensen
2018-01-16 20:20 ` [dpdk-dev] [PATCH] [RFC] ether: standardize getting the port by name Ferruh Yigit
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