test/gc/TestSmallHeap.java

*** 41,58 ****
   * minimal heap size of 2m but on Solaris/Sparc we have a page size of 8k and
   * get a minimal heap size of 4m. And on platforms where the page size is 64k
   * we get a minimal heap size of 32m. We never use large pages for the card table.
   *
   * There is also no check in the VM for verifying that the maximum heap size
!  * is larger than the supported minimal heap size. This means that specifying
!  * -Xmx1m on the command line is fine but will give a heap of 2m (or 4m or 32m).
   *
!  * To work around these rather strange behaviors this test uses -Xmx2m but then
   * calculates what the expected heap size should be. The calculation is a
   * simplified version of the code in the VM. We assume that the card table will
   * use one page. Each byte in the card table corresponds to 512 bytes on the heap.
   * So, the expected heap size is page_size * 512.
   */
  
  import jdk.test.lib.Asserts;
  import jdk.test.lib.process.OutputAnalyzer;
  import jdk.test.lib.process.ProcessTools;
--- 41,62 ----
   * minimal heap size of 2m but on Solaris/Sparc we have a page size of 8k and
   * get a minimal heap size of 4m. And on platforms where the page size is 64k
   * we get a minimal heap size of 32m. We never use large pages for the card table.
   *
   * There is also no check in the VM for verifying that the maximum heap size
!  * is larger than the supported minimal heap size.
   *
!  * To work around these rather strange behaviors this test uses -Xmx4m but then
   * calculates what the expected heap size should be. The calculation is a
   * simplified version of the code in the VM. We assume that the card table will
   * use one page. Each byte in the card table corresponds to 512 bytes on the heap.
   * So, the expected heap size is page_size * 512.
+  *
+  * There is no formal requirement for the minimal value of the maximum heap size
+  * the VM should support. In most cases the VM could start with -Xmx2m.
+  * But with 2m limit GC could be triggered before VM initialization completed.
+  * Therefore, the positive checks start the VM with -Xmx4m as minimum. 
   */
  
  import jdk.test.lib.Asserts;
  import jdk.test.lib.process.OutputAnalyzer;
  import jdk.test.lib.process.ProcessTools;