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 <tho...@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
