On Tue, Aug 18, 2020 at 11:24:30AM +0800, Jason Wang wrote: > > On 2020/8/14 下午1:16, Yan Zhao wrote: > > On Thu, Aug 13, 2020 at 12:24:50PM +0800, Jason Wang wrote: > > > On 2020/8/10 下午3:46, Yan Zhao wrote: > > > > > driver is it handled by? > > > > It looks that the devlink is for network device specific, and in > > > > devlink.h, it says > > > > include/uapi/linux/devlink.h - Network physical device Netlink > > > > interface, > > > > > > Actually not, I think there used to have some discussion last year and the > > > conclusion is to remove this comment. > > > > > > It supports IB and probably vDPA in the future. > > > > > hmm... sorry, I didn't find the referred discussion. only below discussion > > regarding to why to add devlink. > > > > https://www.mail-archive.com/netdev@xxxxxxxxxxxxxxx/msg95801.html > > >This doesn't seem to be too much related to networking? Why can't something > > >like this be in sysfs? > > > > It is related to networking quite bit. There has been couple of > > iteration of this, including sysfs and configfs implementations. There > > has been a consensus reached that this should be done by netlink. I > > believe netlink is really the best for this purpose. Sysfs is not a good > > idea > > > See the discussion here: > > https://patchwork.ozlabs.org/project/netdev/patch/20191115223355.1277139-1-jeffrey.t.kirsher@xxxxxxxxx/ > > > > > > https://www.mail-archive.com/netdev@xxxxxxxxxxxxxxx/msg96102.html > > >there is already a way to change eth/ib via > > >echo 'eth' > /sys/bus/pci/drivers/mlx4_core/0000:02:00.0/mlx4_port1 > > > > > >sounds like this is another way to achieve the same? > > > > It is. However the current way is driver-specific, not correct. > > For mlx5, we need the same, it cannot be done in this way. Do devlink is > > the correct way to go. > > > > https://lwn.net/Articles/674867/ > > There a is need for some userspace API that would allow to expose things > > that are not directly related to any device class like net_device of > > ib_device, but rather chip-wide/switch-ASIC-wide stuff. > > > > Use cases: > > 1) get/set of port type (Ethernet/InfiniBand) > > 2) monitoring of hardware messages to and from chip > > 3) setting up port splitters - split port into multiple ones and squash again, > > enables usage of splitter cable > > 4) setting up shared buffers - shared among multiple ports within one chip > > > > > > > > we actually can also retrieve the same information through sysfs, .e.g > > > > |- [path to device] > > |--- migration > > | |--- self > > | | |---device_api > > | | |---mdev_type > > | | |---software_version > > | | |---device_id > > | | |---aggregator > > | |--- compatible > > | | |---device_api > > | | |---mdev_type > > | | |---software_version > > | | |---device_id > > | | |---aggregator > > > > Yes but: > > - You need one file per attribute (one syscall for one attribute) > - Attribute is coupled with kobject > > All of above seems unnecessary. > > Another point, as we discussed in another thread, it's really hard to make > sure the above API work for all types of devices and frameworks. So having a > vendor specific API looks much better. >From the POV of userspace mgmt apps doing device compat checking / migration, we certainly do NOT want to use different vendor specific APIs. We want to have an API that can be used / controlled in a standard manner across vendors. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
