diff -r ecb72543c632 -r 2f7a2e7c3221 test/hotspot/jtreg/runtime/appcds/sharedStrings/IncompatibleOptions_noCompactStrings.java
--- a/test/hotspot/jtreg/runtime/appcds/sharedStrings/IncompatibleOptions_noCompactStrings.java	Thu Sep 27 13:56:09 2018 +0200
+++ b/test/hotspot/jtreg/runtime/appcds/sharedStrings/IncompatibleOptions_noCompactStrings.java	Fri Oct 05 18:25:15 2018 +0100
@@ -27,6 +27,9 @@
  * @summary Test options that are incompatible with use of shared strings
  *          Also test mismatch in oops encoding between dump time and run time
  * @requires vm.cds.archived.java.heap
+ * @comment This test explicitly chooses the type of GC to be used by sub-processes. It may conflict with the GC type set
+ * via the -vmoptions command line option of JTREG. vm.gc==null will help the test case to discard the explicitly passed
+ * vm options.
  * @requires (vm.gc=="null")
  * @library /test/lib /test/hotspot/jtreg/runtime/appcds
  * @modules jdk.jartool/sun.tools.jar