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What: /sys/bus/css/devices/.../type
Date: March 2008
Contact: Cornelia Huck <cornelia.huck@de.ibm.com>
linux-s390@vger.kernel.org
Description: Contains the subchannel type, as reported by the hardware.
This attribute is present for all subchannel types.
What: /sys/bus/css/devices/.../modalias
Date: March 2008
Contact: Cornelia Huck <cornelia.huck@de.ibm.com>
linux-s390@vger.kernel.org
Description: Contains the module alias as reported with uevents.
It is of the format css:t<type> and present for all
subchannel types.
What: /sys/bus/css/drivers/io_subchannel/.../chpids
Date: December 2002
Contact: Cornelia Huck <cornelia.huck@de.ibm.com>
linux-s390@vger.kernel.org
Description: Contains the ids of the channel paths used by this
subchannel, as reported by the channel subsystem
during subchannel recognition.
Note: This is an I/O-subchannel specific attribute.
Users: s390-tools, HAL
What: /sys/bus/css/drivers/io_subchannel/.../pimpampom
Date: December 2002
Contact: Cornelia Huck <cornelia.huck@de.ibm.com>
linux-s390@vger.kernel.org
Description: Contains the PIM/PAM/POM values, as reported by the
channel subsystem when last queried by the common I/O
layer (this implies that this attribute is not necessarily
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.
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