[announce] driverctl: utility for persistent alternative driver binding

[Panu Matilainen <pmatilai@redhat.com>]

Hi all,

While this is not directly related to DPDK or OVS, it is potentially 
useful for users of both, so excuse me for cross-posting.

Quoting from the project README (for the full text see
http://laiskiainen.org/git/?p=driverctl.git;a=blob_plain;f=README)

 > driverctl is a tool for manipulating and inspecting the system
 > device driver choices.
 >
 > Devices are normally assigned to their sole designated kernel driver
 > by default. However in some situations it may be desireable to
 > override that default, for example to try an older driver to
 > work around a regression in a driver or to try an experimental
 > alternative driver. Another common use-case is pass-through
 > drivers and driver stubs to allow userspace to drive the device,
 > such as in case of virtualization.
 >
 > driverctl integrates with udev to support overriding
 > driver selection for both cold- and hotplugged devices from the
 > moment of discovery, but can also change already assigned drivers,
 > assuming they are not in use by the system. The driver overrides
 > created by driverctl are persistent across system reboots
 > by default.
 >
 > Usage
 > -----
 >
 > Find devices currently driven by ixgbe driver:
 >
 > # driverctl -v list-devices | grep ixgbe
 > 0000:01:00.0 ixgbe (Ethernet 10G 4P X520/I350 rNDC)
 > 0000:01:00.1 ixgbe (Ethernet 10G 4P X520/I350 rNDC)
 >
 > Change them to use the vfio-pci driver:
 > # driverctl set-override 0000:01:00.0 vfio-pci
 > # driverctl set-override 0000:01:00.1 vfio-pci
 >
 > Find devices with driver overrides:
 > # driverctl -v list-devices|grep \\*
 > 0000:01:00.0 vfio-pci [*] (Ethernet 10G 4P X520/I350 rNDC)
 > 0000:01:00.1 vfio-pci [*] (Ethernet 10G 4P X520/I350 rNDC)
 >
 > Remove the override from slot 0000:01:00.1:
 > # driverctl unset-override 0000:01:00.1

DPDK of course has its own dpdk_nic_bind(.py) tool for this purpose, the 
main differences to driverctl are:
- driverctl bindings are persistent across system boots
- driverctl bindings take place immediately on cold- and hotplug
- driverctl is a generic tool not limited to network adapters
- dpdk_nic_bind being a special purpose tool has many more
   sanity checks for its supported use-cases
- dpdk_nic_bind supports binding multiple NICs at once

The project currently lives at
     http://laiskiainen.org/git/?p=driverctl.git

Feedback, patches etc are welcome.

	- Panu -