diff --git a/arch/powerpc/include/asm/pte-8xx.h b/arch/powerpc/include/asm/pte-8xx.h
index 68ba861..d44826e 100644
--- a/arch/powerpc/include/asm/pte-8xx.h
+++ b/arch/powerpc/include/asm/pte-8xx.h
@@ -35,11 +35,12 @@
 #define _PAGE_SPECIAL	0x0008	/* SW entry, forced to 0 by the TLB miss */
 #define _PAGE_DIRTY	0x0100	/* C: page changed */
 
-/* These 3 software bits must be masked out when the entry is loaded
- * into the TLB, 2 SW bits left.
+/* These 4 software bits must be masked out when the entry is loaded
+ * into the TLB, 1 SW bit left(0x0080).
  */
 #define _PAGE_GUARDED	0x0010	/* software: guarded access */
 #define _PAGE_ACCESSED	0x0020	/* software: page referenced */
+#define _PAGE_WRITETHRU	0x0040	/* software: caching is write through */
 
 /* Setting any bits in the nibble with the follow two controls will
  * require a TLB exception handler change.  It is assumed unused bits
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 1a28ee8..c4ae85b 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -422,6 +422,10 @@
 	 * above.
 	 */
 	rlwimi	r11, r10, 0, 27, 27
+	/* Insert the WriteThru flag into the TWC from the Linux PTE.
+	 * It is bit 25 in the Linux PTE and bit 30 in the TWC
+	 */
+	rlwimi	r11, r10, 32-5, 30, 30
 	DO_8xx_CPU6(0x3b80, r3)
 	mtspr	SPRN_MD_TWC, r11
 
@@ -559,6 +563,10 @@
 	 * It is bit 27 of both the Linux PTE and the TWC
 	 */
 	rlwimi	r11, r10, 0, 27, 27
+	/* Insert the WriteThru flag into the TWC from the Linux PTE.
+	 * It is bit 25 in the Linux PTE and bit 30 in the TWC
+	 */
+	rlwimi	r11, r10, 32-5, 30, 30
 	DO_8xx_CPU6(0x3b80, r3)
 	mtspr	SPRN_MD_TWC, r11
 	mfspr	r11, SPRN_MD_TWC	/* get the pte address again */