--- a/src/m/ibmrs6000.h	Mon Aug 13 11:19:22 2007 +0200
+++ b/src/m/ibmrs6000.h	Mon Aug 13 11:20:41 2007 +0200
@@ -51,6 +51,27 @@
 #define DATA_END 0
 #endif
 
+/* The data segment in this machine always starts at address 0x20000000.
+   An address of data cannot be stored correctly in a Lisp object;
+   we always lose the high bits.  We must tell XPNTR to add them back.	*/
+
+#ifndef USG5_4
+#define DATA_SEG_BITS 0x20000000
+#else
+#define DATA_SEG_BITS 0
+#endif
+
+#ifdef CANNOT_DUMP
+/* Define shared memory segment symbols */
+
+#define PURE_SEG_BITS 0x30000000
+
+/* Use shared memory.  */
+/* This is turned off because it does not always work.	See etc/AIX.DUMP.  */
+/* #define HAVE_SHM */
+#define SHMKEY 5305035		/* used for shared memory code segments */
+#endif /* CANNOT_DUMP */
+
 #define N_BADMAG(x) BADMAG(x)
 #define N_TXTOFF(x) A_TEXTPOS(x)
 #define N_SYMOFF(x) A_SYMPOS(x)