On 05/20/2014 05:53 PM, Alex Williamson wrote: > The driver_override field allows us to specify the driver for a device > rather than relying on the driver to provide a positive match of the > device. This shortcuts the existing process of looking up the vendor > and device ID, adding them to the driver new_id, binding the device, > then removing the ID, but it also provides a couple advantages. > > First, the above existing process allows the driver to bind to any > device matching the new_id for the window where it's enabled. This is > often not desired, such as the case of trying to bind a single device > to a meta driver like pci-stub or vfio-pci. Using driver_override we > can do this deterministically using: > > echo pci-stub > /sys/bus/pci/devices/0000:03:00.0/driver_override > echo 0000:03:00.0 > /sys/bus/pci/devices/0000:03:00.0/driver/unbind > echo 0000:03:00.0 > /sys/bus/pci/drivers_probe I'm not qualified to review the mechanics of the patch, but as a potential consumer of this new interface (in libvirt), I want to say that it is *immensely* improved over the racy, error prone method that the kernel currently has available. The first day that I looked at the libvirt code that uses the "new_id" method to bind drivers to devices, I wished that there would instead be an interface more or less identical to what Alex has described here - simple, deterministic, and with minimal side effect outside of the exact device and driver pair we want to bind. -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
