kern/54064: modules/t_kcov tests fail randomly

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         54064
>Category:       kern
>Synopsis:       modules/t_kcov tests fail randomly
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Mar 16 15:35:00 +0000 2019
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current
>Organization:

>Environment:
System: NetBSD
Architecture: x86_64
Machine: amd64
>Description:

Running the ATF tests on real amd64 hardware, I'm seeing random
failures in modules/t_kcov.  For example, in this test report:

  http://www.gson.org/netbsd/bugs/build/amd64-baremetal/2019/2019.03.16.10.45.06/test.html#modules_t_kcov_kcov_multiple_threads8

most of the tests were skipped, but kcov_multiple_threads8 reported

  FAILED: Test case exited normally but failed to create the results file: Results file is empty

>How-To-Repeat:

>Fix: