5 files changed, 38 insertions, 6 deletions
diff --git a/erts/emulator/beam/atom.c b/erts/emulator/beam/atom.c
index dfc3cde6a7..3a231206ae 100644
--- a/erts/emulator/beam/atom.c
+++ b/erts/emulator/beam/atom.c
@@ -322,7 +322,7 @@ init_atom_table(void)
     text_list = NULL;
 
     erts_index_init(ERTS_ALC_T_ATOM_TABLE, &erts_atom_table,
-		    "atom_tab", ATOM_SIZE, ATOM_LIMIT, f);
+		    "atom_tab", ATOM_SIZE, erts_atom_table_size, f);
     more_atom_space();
 
     /* Ordinary atoms */
diff --git a/erts/emulator/beam/atom.h b/erts/emulator/beam/atom.h
index e7e0dc440d..c10218e431 100644
--- a/erts/emulator/beam/atom.h
+++ b/erts/emulator/beam/atom.h
@@ -28,6 +28,17 @@
 
 #define MAX_ATOM_LENGTH 255
 #define ATOM_LIMIT (1024*1024)
+#define MIN_ATOM_TABLE_SIZE 8192
+
+#ifndef ARCH_32
+/* Internal atom cache needs MAX_ATOM_TABLE_SIZE to be less than an
+   unsigned 32 bit integer. See external.c(erts_encode_ext_dist_header_setup)
+   for more details. */
+#define MAX_ATOM_TABLE_SIZE ((MAX_ATOM_INDEX + 1 < (1UL << 32)) ? MAX_ATOM_INDEX + 1 : (1UL << 32))
+#else
+#define MAX_ATOM_TABLE_SIZE (MAX_ATOM_INDEX + 1)
+#endif
+
 
 /*
  * Atom entry.
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index bdf888eaff..17cf3b9597 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -119,6 +119,8 @@ int erts_disable_tolerant_timeofday; /* Time correction can be disabled it is
 				      * not and/or it is too slow.
 				      */
 
+int erts_atom_table_size = ATOM_LIMIT;	/* Maximum number of atoms */
+
 int erts_modified_timing_level;
 
 int erts_no_crash_dump = 0;	/* Use -d to suppress crash dump. */
@@ -569,6 +571,10 @@ void erts_usage(void)
     erts_fprintf(stderr, "            schedulers online (n2), valid range for both\n");
     erts_fprintf(stderr, "            numbers are [1-%d]\n",
 		 ERTS_MAX_NO_OF_SCHEDULERS);
+    erts_fprintf(stderr, "-t size     set the maximum number of atoms the "
+			 "emulator can handle\n");
+    erts_fprintf(stderr, "            valid range is [%d-%d]\n",
+		 MIN_ATOM_TABLE_SIZE, MAX_ATOM_TABLE_SIZE);
     erts_fprintf(stderr, "-T number   set modified timing level,\n");
     erts_fprintf(stderr, "            valid range is [0-%d]\n",
 		 ERTS_MODIFIED_TIMING_LEVELS-1);
@@ -1140,6 +1146,22 @@ erl_start(int argc, char **argv)
 	    }
 	    break;
 	}
+	case 't':
+	    /* set atom table size */
+	    arg = get_arg(argv[i]+2, argv[i+1], &i);
+	    errno = 0;
+	    erts_atom_table_size = strtol(arg, NULL, 10);
+	    if (errno != 0 ||
+		erts_atom_table_size < MIN_ATOM_TABLE_SIZE ||
+		erts_atom_table_size > MAX_ATOM_TABLE_SIZE) {
+		erts_fprintf(stderr, "bad atom table size %s\n", arg);
+		erts_usage();
+	    }
+	    VERBOSE(DEBUG_SYSTEM,
+                    ("setting maximum number of atoms to %d\n",
+		     erts_atom_table_size));
+	    break;
+
 	case 'T' :
 	    arg = get_arg(argv[i]+2, argv[i+1], &i);
 	    errno = 0;
diff --git a/erts/emulator/beam/erl_vm.h b/erts/emulator/beam/erl_vm.h
index 5b0d3c2bfa..50b3e5b61c 100644
--- a/erts/emulator/beam/erl_vm.h
+++ b/erts/emulator/beam/erl_vm.h
@@ -181,6 +181,8 @@ extern int num_instructions;	/* Number of instruction in opc[]. */
 extern int H_MIN_SIZE;		/* minimum (heap + stack) */
 extern int BIN_VH_MIN_SIZE;	/* minimum virtual (bin) heap */
 
+extern int erts_atom_table_size;/* Atom table size */
+
 #define ORIG_CREATION 0
 
 /* macros for extracting bytes from uint16's */
diff --git a/erts/emulator/beam/external.c b/erts/emulator/beam/external.c
index 24887b3dea..b011d4c0de 100644
--- a/erts/emulator/beam/external.c
+++ b/erts/emulator/beam/external.c
@@ -271,11 +271,8 @@ erts_encode_ext_dist_header_size(ErtsAtomCacheMap *acmp)
 
 byte *erts_encode_ext_dist_header_setup(byte *ctl_ext, ErtsAtomCacheMap *acmp)
 {
-#ifndef ARCH_32
-#if ATOM_LIMIT >= (1UL << 32)
-#error "ATOM_LIMIT too large for interal atom cache update instructions. New instructions needed."
-#endif
-#endif
+    /* Maximum number of atom must be less than the maximum of a 32 bits
+       unsigned integer. Check is done in erl_init.c, erl_start function. */
     if (!acmp)
 	return ctl_ext;
     else {