diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 1aad0d9f5074..fd7620f025fa 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -358,7 +358,14 @@ config SGI_IP22
 	select SWAP_IO_SPACE
 	select SYS_HAS_CPU_R4X00
 	select SYS_HAS_CPU_R5000
-	select SYS_HAS_EARLY_PRINTK
+	#
+	# Disable EARLY_PRINTK for now since it leads to overwritten prom
+	# memory during early boot on some machines.
+	#
+	# See http://www.linux-mips.org/cgi-bin/mesg.cgi?a=linux-mips&i=20091119164009.GA15038%40deprecation.cyrius.com
+	# for a more details discussion
+	#
+	# select SYS_HAS_EARLY_PRINTK
 	select SYS_SUPPORTS_32BIT_KERNEL
 	select SYS_SUPPORTS_64BIT_KERNEL
 	select SYS_SUPPORTS_BIG_ENDIAN
@@ -410,7 +417,14 @@ config SGI_IP28
 	select SGI_HAS_ZILOG
 	select SWAP_IO_SPACE
 	select SYS_HAS_CPU_R10000
-	select SYS_HAS_EARLY_PRINTK
+	#
+	# Disable EARLY_PRINTK for now since it leads to overwritten prom
+	# memory during early boot on some machines.
+	#
+	# See http://www.linux-mips.org/cgi-bin/mesg.cgi?a=linux-mips&i=20091119164009.GA15038%40deprecation.cyrius.com
+	# for a more details discussion
+	#
+	# select SYS_HAS_EARLY_PRINTK
 	select SYS_SUPPORTS_64BIT_KERNEL
 	select SYS_SUPPORTS_BIG_ENDIAN
       help
@@ -1439,6 +1453,7 @@ choice
 
 config PAGE_SIZE_4KB
 	bool "4kB"
+	depends on !CPU_LOONGSON2
 	help
 	 This option select the standard 4kB Linux page size.  On some
 	 R3000-family processors this is the only available page size.  Using
@@ -1763,7 +1778,7 @@ config SYS_SUPPORTS_SMARTMIPS
 
 config ARCH_FLATMEM_ENABLE
 	def_bool y
-	depends on !NUMA
+	depends on !NUMA && !CPU_LOONGSON2
 
 config ARCH_DISCONTIGMEM_ENABLE
 	bool
diff --git a/arch/mips/include/asm/mman.h b/arch/mips/include/asm/mman.h
index a2250f390a29..c892bfb3e2c1 100644
--- a/arch/mips/include/asm/mman.h
+++ b/arch/mips/include/asm/mman.h
@@ -75,6 +75,7 @@
 
 #define MADV_MERGEABLE   12		/* KSM may merge identical pages */
 #define MADV_UNMERGEABLE 13		/* KSM may not merge identical pages */
+#define MADV_HWPOISON    100		/* poison a page for testing */
 
 /* compatibility flags */
 #define MAP_FILE	0
diff --git a/arch/mips/include/asm/system.h b/arch/mips/include/asm/system.h
index fcf5f98d90cc..83b5509e09e8 100644
--- a/arch/mips/include/asm/system.h
+++ b/arch/mips/include/asm/system.h
@@ -12,6 +12,7 @@
 #ifndef _ASM_SYSTEM_H
 #define _ASM_SYSTEM_H
 
+#include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/irqflags.h>
 
@@ -193,10 +194,6 @@ extern __u64 __xchg_u64_unsupported_on_32bit_kernels(volatile __u64 * m, __u64 v
 #define __xchg_u64 __xchg_u64_unsupported_on_32bit_kernels
 #endif
 
-/* This function doesn't exist, so you'll get a linker error
-   if something tries to do an invalid xchg().  */
-extern void __xchg_called_with_bad_pointer(void);
-
 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
 {
 	switch (size) {
@@ -205,11 +202,17 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz
 	case 8:
 		return __xchg_u64(ptr, x);
 	}
-	__xchg_called_with_bad_pointer();
+
 	return x;
 }
 
-#define xchg(ptr, x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
+#define xchg(ptr, x)							\
+({									\
+	BUILD_BUG_ON(sizeof(*(ptr)) & ~0xc);				\
+									\
+	((__typeof__(*(ptr)))						\
+		__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))));	\
+})
 
 extern void set_handler(unsigned long offset, void *addr, unsigned long len);
 extern void set_uncached_handler(unsigned long offset, void *addr, unsigned long len);