** Description changed:

  [Impact]
- kprobes are not available on arm64, a useful debug feature available on all 
other supported Ubuntu architectures. I failed to catch this when I reviewed 
the yakkety config because I was just looking for regressions vs. enabling new 
features (arm64/kprobes is new in 4.8).
+ kprobes is currently enabled for all Ubuntu architectures except arm64. This 
excludes a useful debug feature, which is required by certain userspace 
provided by Ubuntu, such as perf's probe command. I failed to notice this in my 
yakkety config review because it is a new feature in v4.8.
  
  [Test Case]
- sudo perf probe schedule
- sudo perf record -e probe:schedule -aR sleep 1
+ = Failure case =
+ ubuntu@arm64:~$ sudo perf probe schedule
+ kprobe_events file does not exist - please rebuild kernel with 
CONFIG_KPROBE_EVENTS.
+   Error: Failed to add events.
+ 
+ = Success case =
+ ubuntu@arm64:~$ sudo perf probe schedule
+ Added new event:
+   probe:schedule       (on schedule)
+ 
+ You can now use it in all perf tools, such as:
+ 
+         perf record -e probe:schedule -aR sleep 1
+ 
+ ubuntu@arm64:~$ sudo perf record -e probe:schedule -aR sleep 1
+ [ perf record: Woken up 1 times to write data ]
+ [ perf record: Captured and wrote 0.185 MB perf.data (61 samples) ]
  
  [Regression Risk]
  The proposed fix enables a config for an already-upstream feature, so 
regressions will have upstream support. The config change mostly results in 
building new code vs. modifying existing code. The notable exception is that 
arm64's notify_page_fault() will now get code to call kprobe_fault_handler() - 
but only in the case that this newly enabled feature is being used (if 
kprobe_running()).

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https://bugs.launchpad.net/bugs/1634271

Title:
  arm64: kprobes disabled

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