diff --git a/include/sys/isa_defs.h b/include/sys/isa_defs.h
index 3730561da5..57a6d366e9 100644
--- a/include/sys/isa_defs.h
+++ b/include/sys/isa_defs.h
@@ -1,4 +1,68 @@
 #ifndef	_SPL_ISA_DEFS_H
 #define	_SPL_ISA_DEFS_H
 
+#ifdef  __cplusplus
+extern "C" {
+#endif
+
+/* x86_64 arch specific defines */
+#if defined(__x86_64) || defined(__x86_64__)
+
+#if !defined(__x86_64)
+#define __x86_64
+#endif
+
+#if !defined(__amd64)
+#define __amd64
+#endif
+
+#if !defined(__x86)
+#define __x86
+#endif
+
+#if !defined(_LP64)
+#define _LP64
+#endif
+
+/* i386 arch specific defines */
+#elif defined(__i386) || defined(__i386__)
+
+#if !defined(__i386)
+#define __i386
+#endif
+
+#if !defined(__x86)
+#define __x86
+#endif
+
+#if !defined(_ILP32)
+#define _ILP32
+#endif
+
+#else /* Currently only x86_64 and i386 arches supported */
+#error "Unsupported ISA type"
+#endif
+
+#if defined(_ILP32) && defined(_LP64)
+#error "Both _ILP32 and _LP64 are defined"
+#endif
+
+#include <sys/byteorder.h>
+
+#if defined(__LITTLE_ENDIAN) && !defined(_LITTLE_ENDIAN)
+#define _LITTLE_ENDIAN __LITTLE_ENDIAN
+#endif
+
+#if defined(__BIG_ENDIAN) && !defined(_BIG_ENDIAN)
+#define _BIG_ENDIAN __BIG_ENDIAN
+#endif
+
+#if defined(_LITTLE_ENDIAN) && defined(_BIG_ENDIAN)
+#error "Both _LITTLE_ENDIAN and __BIG_ENDIAN are defined"
+#endif
+
+#ifdef  __cplusplus
+}
+#endif
+
 #endif	/* _SPL_ISA_DEFS_H */
diff --git a/include/sys/kmem.h b/include/sys/kmem.h
index 393775fab9..a33643f158 100644
--- a/include/sys/kmem.h
+++ b/include/sys/kmem.h
@@ -34,7 +34,7 @@ extern int kmem_warning_flag;
 ({      void *_ptr_;                                                          \
                                                                               \
 	/* Marked unlikely because we should never be doing this */           \
-        if (unlikely((size) > (PAGE_SIZE * 2)) && kmem_warning_flag)          \
+        if (unlikely((size) > (PAGE_SIZE * 4)) && kmem_warning_flag)          \
                 printk("spl: Warning kmem_alloc(%d, 0x%x) large alloc at %s:%d "\
                        "(%ld/%ld)\n", (int)(size), (int)(flags),              \
 		       __FILE__, __LINE__,                                    \