diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 0fed81d91e034f86b593bc1257080b9e141ae703..50f657e773449e29d1fa2d64ad5c8e87047f9bd2 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -14,7 +14,7 @@ CFLAGS_ptrace.o		+= -DUTS_MACHINE='"$(UTS_MACHINE)"'
 
 obj-y	:=  bitmap.o traps.o time.o process.o base.o early.o \
             setup.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o \
-	    s390_ext.o debug.o irq.o ipl.o dis.o diag.o
+	    s390_ext.o debug.o irq.o ipl.o dis.o diag.o mem_detect.o
 
 obj-y	+= $(if $(CONFIG_64BIT),entry64.o,entry.o)
 obj-y	+= $(if $(CONFIG_64BIT),reipl64.o,reipl.o)
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index e22473993dc998b6ddb3625ef1dcdd7c5fbd7529..4c0ec7b46e37a10f460847370035d44f3e936c2f 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -192,100 +192,6 @@ static noinline __init void detect_machine_type(void)
 		machine_flags |= MACHINE_FLAG_KVM;
 }
 
-#ifdef CONFIG_64BIT
-static noinline __init int memory_fast_detect(void)
-{
-	unsigned long val0 = 0;
-	unsigned long val1 = 0xc;
-	int ret = -ENOSYS;
-
-	if (ipl_flags & IPL_NSS_VALID)
-		return -ENOSYS;
-
-	asm volatile(
-		"	diag	%1,%2,0x260\n"
-		"0:	lhi	%0,0\n"
-		"1:\n"
-		EX_TABLE(0b,1b)
-		: "+d" (ret), "+d" (val0), "+d" (val1) : : "cc");
-
-	if (ret || val0 != val1)
-		return -ENOSYS;
-
-	memory_chunk[0].size = val0 + 1;
-	return 0;
-}
-#else
-static inline int memory_fast_detect(void)
-{
-	return -ENOSYS;
-}
-#endif
-
-static inline __init unsigned long __tprot(unsigned long addr)
-{
-	int cc = -1;
-
-	asm volatile(
-		"	tprot	0(%1),0\n"
-		"0:	ipm	%0\n"
-		"	srl	%0,28\n"
-		"1:\n"
-		EX_TABLE(0b,1b)
-		: "+d" (cc) : "a" (addr) : "cc");
-	return (unsigned long)cc;
-}
-
-/* Checking memory in 128KB increments. */
-#define CHUNK_INCR	(1UL << 17)
-#define ADDR2G		(1UL << 31)
-
-static noinline __init void find_memory_chunks(unsigned long memsize)
-{
-	unsigned long addr = 0, old_addr = 0;
-	unsigned long old_cc = CHUNK_READ_WRITE;
-	unsigned long cc;
-	int chunk = 0;
-
-	while (chunk < MEMORY_CHUNKS) {
-		cc = __tprot(addr);
-		while (cc == old_cc) {
-			addr += CHUNK_INCR;
-			if (memsize && addr >= memsize)
-				break;
-#ifndef CONFIG_64BIT
-			if (addr == ADDR2G)
-				break;
-#endif
-			cc = __tprot(addr);
-		}
-
-		if (old_addr != addr &&
-		    (old_cc == CHUNK_READ_WRITE || old_cc == CHUNK_READ_ONLY)) {
-			memory_chunk[chunk].addr = old_addr;
-			memory_chunk[chunk].size = addr - old_addr;
-			memory_chunk[chunk].type = old_cc;
-			chunk++;
-		}
-
-		old_addr = addr;
-		old_cc = cc;
-
-#ifndef CONFIG_64BIT
-		if (addr == ADDR2G)
-			break;
-#endif
-		/*
-		 * Finish memory detection at the first hole
-		 * if storage size is unknown.
-		 */
-		if (cc == -1UL && !memsize)
-			break;
-		if (memsize && addr >= memsize)
-			break;
-	}
-}
-
 static __init void early_pgm_check_handler(void)
 {
 	unsigned long addr;
@@ -465,8 +371,6 @@ static void __init setup_boot_command_line(void)
  */
 void __init startup_init(void)
 {
-	unsigned long long memsize;
-
 	ipl_save_parameters();
 	rescue_initrd();
 	clear_bss_section();
@@ -486,18 +390,7 @@ void __init startup_init(void)
 	detect_diag44();
 	detect_machine_facilities();
 	setup_hpage();
-	sclp_read_info_early();
 	sclp_facilities_detect();
-	memsize = sclp_memory_detect();
-#ifndef CONFIG_64BIT
-	/*
-	 * Can't deal with more than 2G in 31 bit addressing mode, so
-	 * limit the value in order to avoid strange side effects.
-	 */
-	if (memsize > ADDR2G)
-		memsize = ADDR2G;
-#endif
-	if (memory_fast_detect() < 0)
-		find_memory_chunks((unsigned long) memsize);
+	detect_memory_layout(memory_chunk);
 	lockdep_on();
 }
diff --git a/arch/s390/kernel/mem_detect.c b/arch/s390/kernel/mem_detect.c
new file mode 100644
index 0000000000000000000000000000000000000000..18ed7abe16c590e7c2d5bd6047372d3273b932ad
--- /dev/null
+++ b/arch/s390/kernel/mem_detect.c
@@ -0,0 +1,100 @@
+/*
+ *    Copyright IBM Corp. 2008
+ *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <asm/ipl.h>
+#include <asm/sclp.h>
+#include <asm/setup.h>
+
+static int memory_fast_detect(struct mem_chunk *chunk)
+{
+	unsigned long val0 = 0;
+	unsigned long val1 = 0xc;
+	int rc = -EOPNOTSUPP;
+
+	if (ipl_flags & IPL_NSS_VALID)
+		return -EOPNOTSUPP;
+	asm volatile(
+		"	diag	%1,%2,0x260\n"
+		"0:	lhi	%0,0\n"
+		"1:\n"
+		EX_TABLE(0b,1b)
+		: "+d" (rc), "+d" (val0), "+d" (val1) : : "cc");
+
+	if (rc || val0 != val1)
+		return -EOPNOTSUPP;
+	chunk->size = val0 + 1;
+	return 0;
+}
+
+static inline int tprot(unsigned long addr)
+{
+	int rc = -EFAULT;
+
+	asm volatile(
+		"	tprot	0(%1),0\n"
+		"0:	ipm	%0\n"
+		"	srl	%0,28\n"
+		"1:\n"
+		EX_TABLE(0b,1b)
+		: "+d" (rc) : "a" (addr) : "cc");
+	return rc;
+}
+
+#define ADDR2G (1ULL << 31)
+
+static void find_memory_chunks(struct mem_chunk chunk[])
+{
+	unsigned long long memsize, rnmax, rzm;
+	unsigned long addr = 0, size;
+	int i = 0, type;
+
+	rzm = sclp_get_rzm();
+	rnmax = sclp_get_rnmax();
+	memsize = rzm * rnmax;
+	if (!rzm)
+		rzm = 1ULL << 17;
+	if (sizeof(long) == 4) {
+		rzm = min(ADDR2G, rzm);
+		memsize = memsize ? min(ADDR2G, memsize) : ADDR2G;
+	}
+	do {
+		size = 0;
+		type = tprot(addr);
+		do {
+			size += rzm;
+			if (memsize && addr + size >= memsize)
+				break;
+		} while (type == tprot(addr + size));
+		if (type == CHUNK_READ_WRITE || type == CHUNK_READ_ONLY) {
+			chunk[i].addr = addr;
+			chunk[i].size = size;
+			chunk[i].type = type;
+			i++;
+		}
+		addr += size;
+	} while (addr < memsize && i < MEMORY_CHUNKS);
+}
+
+void detect_memory_layout(struct mem_chunk chunk[])
+{
+	unsigned long flags, cr0;
+
+	memset(chunk, 0, MEMORY_CHUNKS * sizeof(struct mem_chunk));
+	if (memory_fast_detect(&chunk[0]) == 0)
+		return;
+	/* Disable IRQs, DAT and low address protection so tprot does the
+	 * right thing and we don't get scheduled away with low address
+	 * protection disabled.
+	 */
+	flags = __raw_local_irq_stnsm(0xf8);
+	__ctl_store(cr0, 0, 0);
+	__ctl_clear_bit(0, 28);
+	find_memory_chunks(chunk);
+	__ctl_load(cr0, 0, 0);
+	__raw_local_irq_ssm(flags);
+}
+EXPORT_SYMBOL(detect_memory_layout);
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index e3b4cdbae34e914d495b799f960a166c40570b9d..9c92407f625c1ab972750d2b850a06727a36fa3a 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -77,7 +77,7 @@ unsigned long machine_flags;
 unsigned long elf_hwcap = 0;
 char elf_platform[ELF_PLATFORM_SIZE];
 
-struct mem_chunk __meminitdata memory_chunk[MEMORY_CHUNKS];
+struct mem_chunk __initdata memory_chunk[MEMORY_CHUNKS];
 volatile int __cpu_logical_map[NR_CPUS]; /* logical cpu to cpu address */
 static unsigned long __initdata memory_end;
 
diff --git a/drivers/s390/char/sclp_cmd.c b/drivers/s390/char/sclp_cmd.c
index 4f45884c92c3fa71cf7c19e7068b0ad7bd13937e..0c2b77493db44ae564033ea20e247330c0951ae2 100644
--- a/drivers/s390/char/sclp_cmd.c
+++ b/drivers/s390/char/sclp_cmd.c
@@ -67,7 +67,7 @@ static int __init sclp_cmd_sync_early(sclp_cmdw_t cmd, void *sccb)
 	return rc;
 }
 
-void __init sclp_read_info_early(void)
+static void __init sclp_read_info_early(void)
 {
 	int rc;
 	int i;
@@ -97,30 +97,33 @@ void __init sclp_read_info_early(void)
 
 void __init sclp_facilities_detect(void)
 {
-	if (!early_read_info_sccb_valid)
-		return;
-	sclp_facilities = early_read_info_sccb.facilities;
-	sclp_fac84 = early_read_info_sccb.fac84;
-}
-
-unsigned long long __init sclp_memory_detect(void)
-{
-	unsigned long long memsize;
 	struct read_info_sccb *sccb;
 
+	sclp_read_info_early();
 	if (!early_read_info_sccb_valid)
-		return 0;
+		return;
+
 	sccb = &early_read_info_sccb;
+	sclp_facilities = sccb->facilities;
+	sclp_fac84 = sccb->fac84;
 	rnmax = sccb->rnmax ? sccb->rnmax : sccb->rnmax2;
 	rzm = sccb->rnsize ? sccb->rnsize : sccb->rnsize2;
 	rzm <<= 20;
-	memsize = rzm * rnmax;
-	return memsize;
+}
+
+unsigned long long sclp_get_rnmax(void)
+{
+	return rnmax;
+}
+
+unsigned long long sclp_get_rzm(void)
+{
+	return rzm;
 }
 
 /*
- * This function will be called after sclp_memory_detect(), which gets called
- * early from early.c code. Therefore the sccb should have valid contents.
+ * This function will be called after sclp_facilities_detect(), which gets
+ * called from early.c code. Therefore the sccb should have valid contents.
  */
 void __init sclp_get_ipl_info(struct sclp_ipl_info *info)
 {
diff --git a/include/asm-s390/sclp.h b/include/asm-s390/sclp.h
index b5f2843013a346902741fe2cfa8031ff4f3e8ea7..fed7bee650a06868072ef323723d7e6abe2336d7 100644
--- a/include/asm-s390/sclp.h
+++ b/include/asm-s390/sclp.h
@@ -45,9 +45,9 @@ struct sclp_cpu_info {
 int sclp_get_cpu_info(struct sclp_cpu_info *info);
 int sclp_cpu_configure(u8 cpu);
 int sclp_cpu_deconfigure(u8 cpu);
-void sclp_read_info_early(void);
 void sclp_facilities_detect(void);
-unsigned long long sclp_memory_detect(void);
+unsigned long long sclp_get_rnmax(void);
+unsigned long long sclp_get_rzm(void);
 int sclp_sdias_blk_count(void);
 int sclp_sdias_copy(void *dest, int blk_num, int nr_blks);
 int sclp_chp_configure(struct chp_id chpid);
diff --git a/include/asm-s390/setup.h b/include/asm-s390/setup.h
index f5eebc48d98d2b478e565b5af84a067d75506938..80747ba6ef8a4aa352b32e40ef76b3030cc7196a 100644
--- a/include/asm-s390/setup.h
+++ b/include/asm-s390/setup.h
@@ -17,7 +17,7 @@
 #include <asm/types.h>
 
 #define PARMAREA		0x10400
-#define MEMORY_CHUNKS		16	/* max 0x7fff */
+#define MEMORY_CHUNKS		256
 
 #ifndef __ASSEMBLY__
 
@@ -38,12 +38,14 @@
 struct mem_chunk {
 	unsigned long addr;
 	unsigned long size;
-	unsigned long type;
+	int type;
 };
 
 extern struct mem_chunk memory_chunk[];
 extern unsigned long real_memory_size;
 
+void detect_memory_layout(struct mem_chunk chunk[]);
+
 #ifdef CONFIG_S390_SWITCH_AMODE
 extern unsigned int switch_amode;
 #else