java/nio/MappedByteBuffer/Truncate.java fails on jdk8 s390x Zero with:

#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (os_linux_zero.cpp:202), pid=61427, tid=0x000003ff63fff910
# Error: ShouldNotCall()
#
# JRE version: OpenJDK Runtime Environment (8.0_202-b08) (build 1.8.0_202-201903300430-b08)
# Java VM: OpenJDK 64-Bit Zero VM (25.202-b08 interpreted mode linux-s390x )
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# /data/jenkins/workspace/openjdk8_hs_openjdktest_s390x_linux/jvmtest/openjdk_regression/work/scratch/2/hs_err_pid61427.log
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
#

Zero doesn't support unsafe accesses as they are platform specific. The method on TOS is sun.misc.Unsafe.getByte(J)B called by java.nio.MappedByteBuffer.load()Ljava/nio/MappedByteBuffer. Unless this is implemented, the test should be excluded.