Summary

The upper bound for the GCCardSizeInBytes option must be 512 bytes for 32 bit platforms.

Problem

In JDK-8275142 the new option GCCardSizeInBytes as been introduced with upper bounds of 1024 bytes for all platforms. This value does not work for 32 bit platforms due to implementation limitations.

Solution

Reduce the upper bound of GCCardSizeInBytes to 512 bytes for 32 bit platforms.

Specification

diff --git a/src/hotspot/share/gc/shared/gc_globals.hpp b/src/hotspot/share/gc/shared/gc_globals.hpp
index b57be5abf62..684357297d8 100644
--- a/src/hotspot/share/gc/shared/gc_globals.hpp
+++ b/src/hotspot/share/gc/shared/gc_globals.hpp
@@ -696,7 +696,7 @@
                                                                             \
   product(uint, GCCardSizeInBytes, 512,                                     \
           "Card table entry size (in bytes) for card based collectors")     \
-          range(128, 1024)                                                  \
+          range(128, NOT_LP64(512) LP64_ONLY(1024))                         \
           constraint(GCCardSizeInBytesConstraintFunc,AtParse)
   // end of GC_FLAGS