> -----Original Message----- > From: Christophe de Dinechin <christophe.de.dinechin@xxxxxxxxx> > Subject: Re: [PATCH v2 0/2] Simplify mtty driver and mdev core > > > Parav Pandit writes: > > > + Dave. > > > > Hi Jiri, Dave, Alex, Kirti, Cornelia, > > > > Please provide your feedback on it, how shall we proceed? > > > > Hence, I would like to discuss below options. > > > > Option-1: mdev index > > Introduce an optional mdev index/handle as u32 during mdev create time. > > User passes mdev index/handle as input. > > > > phys_port_name=mIndex=m%u > > mdev_index will be available in sysfs as mdev attribute for udev to name the > mdev's netdev. > > > > example mdev create command: > > UUID=$(uuidgen) > > echo $UUID index=10 > > > /sys/class/net/ens2f0/mdev_supported_types/mlx5_core_mdev/create > > example netdevs: > > repnetdev=ens2f0_m10 /*ens2f0 is parent PF's netdevice */ > > mdev_netdev=enm10 > > > > Pros: > > 1. mdevctl and any other existing tools are unaffected. > > 2. netdev stack, ovs and other switching platforms are unaffected. > > 3. achieves unique phys_port_name for representor netdev 4. achieves > > unique mdev eth netdev name for the mdev using udev/systemd extension. > > 5. Aligns well with mdev and netdev subsystem and similar to existing sriov > bdf's. > > > > Option-2: shorter mdev name > > Extend mdev to have shorter mdev device name in addition to UUID. > > such as 'foo', 'bar'. > > Mdev will continue to have UUID. > > phys_port_name=mdev_name > > > > Pros: > > 1. All same as option-1, except mdevctl needs upgrade for newer usage. > > It is common practice to upgrade iproute2 package along with the kernel. > > Similar practice to be done with mdevctl. > > 2. Newer users of mdevctl who wants to work with non_UUID names, will use > newer mdevctl/tools. > > Cons: > > 1. Dual naming scheme of mdev might affect some of the existing tools. > > It's unclear how/if it actually affects. > > mdevctl [2] is very recently developed and can be enhanced for dual naming > scheme. > > > > Option-3: mdev uuid alias > > Instead of shorter mdev name or mdev index, have alpha-numeric name > alias. > > Alias is an optional mdev sysfs attribute such as 'foo', 'bar'. > > example mdev create command: > > UUID=$(uuidgen) > > echo $UUID alias=foo > > > /sys/class/net/ens2f0/mdev_supported_types/mlx5_core_mdev/create > > example netdevs: > > examle netdevs: > > repnetdev = ens2f0_mfoo > > mdev_netdev=enmfoo > > > > Pros: > > 1. All same as option-1. > > 2. Doesn't affect existing mdev naming scheme. > > Cons: > > 1. Index scheme of option-1 is better which can number large number of > mdevs with fewer characters, simplifying the management tool. > > I believe that Alex pointed out another "Cons" to all three options, which is that > it forces user-space to resolve potential race conditions when creating an index > or short name or alias. > This race condition exists for at least two subsystems that I know of, i.e. netdev and rdma. If a device with a given name exists, subsystem returns error. When user space gets error code EEXIST, and it can picks up different identifier(s). > Also, what happens if `index=10` is not provided on the command-line? > Does that make the device unusable for your purpose? Yes, it is unusable to an extent. Currently we have DEVLINK_PORT_FLAVOUR_PCI_VF in include/uapi/linux/devlink.h Similar to it, we need to have DEVLINK_PORT_FLAVOUR_MDEV for mdev eswitch ports. This port flavour needs to generate phys_port_name(). This should be user parameter driven. Because representor netdevice name is generated based on this parameter.
