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Diffstat (limited to 'Documentation/ABI/testing/sysfs-bus-css')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-css | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-css b/Documentation/ABI/testing/sysfs-bus-css index 2979c40c10e9..966f8504bd7b 100644 --- a/Documentation/ABI/testing/sysfs-bus-css +++ b/Documentation/ABI/testing/sysfs-bus-css @@ -33,3 +33,26 @@ Description: Contains the PIM/PAM/POM values, as reported by the in sync with the values current in the channel subsystem). Note: This is an I/O-subchannel specific attribute. Users: s390-tools, HAL + +What: /sys/bus/css/devices/.../driver_override +Date: June 2019 +Contact: Cornelia Huck <cohuck@redhat.com> + linux-s390@vger.kernel.org +Description: This file allows the driver for a device to be specified. When + specified, only a driver with a name matching the value written + to driver_override will have an opportunity to bind to the + device. The override is specified by writing a string to the + driver_override file (echo vfio-ccw > driver_override) and + may be cleared with an empty string (echo > driver_override). + This returns the device to standard matching rules binding. + Writing to driver_override does not automatically unbind the + device from its current driver or make any attempt to + automatically load the specified driver. If no driver with a + matching name is currently loaded in the kernel, the device + will not bind to any driver. This also allows devices to + opt-out of driver binding using a driver_override name such as + "none". Only a single driver may be specified in the override, + there is no support for parsing delimiters. + Note that unlike the mechanism of the same name for pci, this + file does not allow to override basic matching rules. I.e., + the driver must still match the subchannel type of the device. |