Messages in this thread | | | Date | Mon, 7 Jun 2021 12:46:43 -0700 | From | Jakub Kicinski <> | Subject | Re: [RFC net-next 0/8] Introducing subdev bus and devlink extension |
| |
On Mon, 7 Jun 2021 09:36:38 +0800 Yunsheng Lin wrote: > On 2021/6/5 2:41, Jakub Kicinski wrote: > > On Fri, 4 Jun 2021 09:18:04 +0800 Yunsheng Lin wrote: > >> My initial thinking is a id from a global IDA pool, which indeed may > >> change on every boot. > >> > >> I am not really thinking much deeper about the controller id, just > >> mirroring the bus identifiers for pcie device and ifindex for netdev, > > > > devlink instance id seems fine, but there's already a controller > > concept in devlink so please steer clear of that naming. > I am not sure if controller concept already existed is reusable for > the devlink instance representing problem for multi-function which > shares common resource in the same ASIC. If not, we do need to pick > up other name. > > Another thing I am not really think throught is how is the VF represented > by the devlink instance when VF is passed through to a VM. > I was thinking about VF is represented as devlink port, just like PF(with > different port flavour), and VF devlink port only exist on the same host > as PF(which assumes PF is never passed through to a VM), so it may means > the PF is responsible for creating the devlink port for VF when VF is passed > through to a VM? > > Or do we need to create a devlink instance for VF in the VM too when the > VF is passed through to a VM? Or more specificly, does user need to query > or configure devlink info or configuration in a VM? If not, then devlink > instance in VM seems unnecessary?
I believe the current best practice is to create a devlink instance for the VF with a devlink port of type "virtual". Such instance represents a "virtualized" view of the device.
> >> which may change too if the device is pluged into different pci slot > >> on every boot? > > > > Heh. What is someone reflashes the part to change it's serial number? :) > > pci slot is reasonably stable, as proven by years of experience trying > > to find stable naming for netdevs. > > I suppose that requires a booting to take effect and a vendor tool > to reflash the serial number, it seems reasonable the vendor/user will > try their best to not mess the serial number, otherwise service and > maintenance based on serial number will not work? > I was thinking about adding the vendor name besides the serial number > to indicate a devlink instance, to avoid that case that two hw from > different vendor having the same serial number accidentally.
I'm not opposed to the use of attributes such as serial number for selecting instance, in principle. I was just trying to prove that PCI slot/PCI device name is as stable as any other attribute.
In fact for mass-produced machines using PCI slot is far more convenient than globally unique identifiers because it can be used to talk to a specific device in a server for all machines of a given model, hence easing automation.
> >> We could still allow devlink instances to have multiple names, > >> which seems to be more like devlink tool problem? > >> > >> For example, devlink tool could use the id or the vendor_info/ > >> serial_number to indicate a devlink instance according to user's > >> request. > > > > Typing serial numbers seems pretty painful. > > > >> Aliase could be allowed too as long as devlink core provide a > >> field and ops to set/get the field mirroring the ifalias for > >> netdevice? > > > > I don't understand. > > I meant we could still allow the user to provide a more meaningful > name to indicate a devlink instance besides the id.
To clarify/summarize my statement above serial number may be a useful addition but PCI device names should IMHO remain the primary identifiers, even if it means devlink instances with multiple names.
In addition I don't think that user-controlled names/aliases are necessarily a great idea for devlink.
| |