[Beignet] few questions on Beignet-OpenCL-ICD v1.2.0 regarding X11 and kernel patches

[Rebecca N. Palmer]

The drm.rnodes=1 kernel parameter mentioned in beignet's documentation 
no longer exists (render nodes are on by default since 
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/gpu/drm/drm_stub.c?id=6d6dfcfb883818b40b58bac61cc72cab428a7a03), 
but it wasn't supposed to be needed if beignet was run as root.

> # strings /usr/local/lib/beignet/libcl.so | grep -i x11
> x11_display
This may not be an actual problem: beignet's internal intel_driver 
structure always has an x11_display field (src/intel/intel_driver.h:89), 
which is set to NULL if there is no such display.  (Though if so, odd 
that my test didn't have that string...)

> There is only beignet-opencl-icd's output, can't find the error message from beignet,
That's because that "beignet-opencl-icd: no supported GPU found, this is 
probably the wrong opencl-icd package for this hardware" message *is* 
the driver's failure message in Debian beignet: 
https://sources.debian.net/src/beignet/1.2.0-1/debian/patches/reduce-notfound-output.patch/

I made this change because the Debian packaging system doesn't really 
have a concept of "this package only works on this hardware", and it is 
hence likely that Debian beignet will get installed on hardware that 
actually needs some other ICD.

(It uses the name beignet-opencl-icd because that's the package name, 
but comes from the usual place in the code, i.e. is _not_ specific to 
the ICD interface.)

You can revert this change by removing the reduce-notfound-output.patch 
line from debian/patches/series and rebuilding the package, but this 
probably won't actually make it work.