Devices can be faked for scalability testing when non-standard paths
are used (GPU plugin code assumes container paths to match host paths,
and container runtime prevents creating fake files under real paths).

Note: If one wants to run both normal GPU plugin and faked one in same
cluster, all nodes providing fake "i915" resources should be labeled
differently from ones with real GPU plugin + devices, so that real GPU
workloads can be limited to correct nodes with a suitable
nodeSelector.

Signed-off-by: Eero Tamminen <eero.t.tamminen@intel.com>

Signed-off-by: Eero Tamminen <eero.t.tamminen@intel.com>

Based on input JSON file

Fake devfs directory is mounted from host so OCI runtime can "mount"
device files also to workloads requesting fake devices. This means
that those files can persist over fake GPU plugin life-time, so
earlier files need to be removed, as they may not match.

Also, DaemonSet restarts failing init containers, so errors about
directories generated on previous generator run would prevent getting
logs of the real error from first generator run.

Represent fake GPU devices with null devices:
https://www.kernel.org/doc/Documentation/admin-guide/devices.txt

Real devfs check needed also changing, and removal warnings
were simplified, as there's always just one entry.

Signed-off-by: Eero Tamminen <eero.t.tamminen@intel.com>

With latest devices release.

Signed-off-by: Eero Tamminen <eero.t.tamminen@intel.com>

Signed-off-by: Eero Tamminen <eero.t.tamminen@intel.com>

Signed-off-by: Eero Tamminen <eero.t.tamminen@intel.com>

As suggested by Ukri.

Signed-off-by: Eero Tamminen <eero.t.tamminen@intel.com>

Give more detailed logging for most likely failure, as MkNod() device
node creation can fail as normal user.

Additional error checking done in new dir removal helper function
fixes Ukri's review comments.  There's now error if to-be-removed fake
sysfs has more content than expected (earlier such check was only for
fake devfs content).

Signed-off-by: Eero Tamminen <eero.t.tamminen@intel.com>

Noticed by Tuomas.

Signed-off-by: Eero Tamminen <eero.t.tamminen@intel.com>