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This patch introduces user space notifications for changes on the apmask or aqmask attributes. So it could be possible to write a udev rule to load/unload the vfio_ap kernel module based on changes of these masks. On chance of the apmask or aqmask an AP change event will be produced with an uevent environment variable showing the new APMASK or AQMASK mask. So a change on the apmask triggers an uvevent like this: KERNEL[490.160396] change /devices/ap (ap) ACTION=change DEVPATH=/devices/ap SUBSYSTEM=ap APMASK=0xffffffdfffffffffffffffffffffffffffffffffffffffffffffffffffffffff SEQNUM=13367 and a change on the aqmask looks like this: KERNEL[283.217642] change /devices/ap (ap) ACTION=change DEVPATH=/devices/ap SUBSYSTEM=ap AQMASK=0xfbffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff SEQNUM=13348 Only real changes to the masks are processed - the old and new masks are compared and no action is done if the values are equal (and thus no uevent). The emit of the uevent is the very last action done when a mask change is processed. However, there is no guarantee that all unbind/bind actions caused by the apmask/aqmask changes are completed when the apmask/aqmask change uevent is received in userspace. Signed-off-by: Harald Freudenberger <freude@linux.ibm.com> Tested-by: Thomas Huth <thuth@redhat.com> Reviewed-by: Jürgen Christ <jchrist@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.