#define SGEN_HAVE_CONCURRENT_MARK
-#define MS_BLOCK_SIZE_SHIFT 14 /* INT FASTENABLE */
-#define MS_BLOCK_SIZE (1 << MS_BLOCK_SIZE_SHIFT)
+#if defined(ARCH_MIN_MS_BLOCK_SIZE) && defined(ARCH_MIN_MS_BLOCK_SIZE_SHIFT)
+#define MS_BLOCK_SIZE ARCH_MIN_MS_BLOCK_SIZE
+#define MS_BLOCK_SIZE_SHIFT ARCH_MIN_MS_BLOCK_SIZE_SHIFT
+#else
+#define MS_BLOCK_SIZE_SHIFT 14 /* INT FASTENABLE */
+#define MS_BLOCK_SIZE (1 << MS_BLOCK_SIZE_SHIFT)
+#endif
#define MAJOR_SECTION_SIZE MS_BLOCK_SIZE
#define CARDS_PER_BLOCK (MS_BLOCK_SIZE / CARD_SIZE_IN_BYTES)