[systemd-devel] Utility for persistent alternative driver binding

[Panu Matilainen]

Hi all,

To follow-up on this thread from September-October:
http://lists.freedesktop.org/archives/systemd-devel/2015-September/034427.html
http://lists.freedesktop.org/archives/systemd-devel/2015-October/034551.html

The driverctl utility has matured a bit from the earliest tyre-kicking 
version seen there and now lives at laiskiainen.org/git/?p=driverctl.git

Since it has everything to do with udev this seems like a reasonable 
forum to advertise it a bit. Quoting from the README a bit:

> 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

The other reason for posting here is: is there interest in having such a 
utility would find home in udev/systemd?

Note that I'm not trying to sell you the current shell-spaghetti 
implementation, its mostly just a demonstration of the interface which 
is modeled after the various *ctl utilities in systemd. The idea is to 
rewrite it properly in C anyway, but at this point it'd be useful to 
know from style/infrastructure/etc perspective whether there's interest 
in having such a thing included in systemd afterall.

	- Panu -