[TRIVIAL][PATCH] document unused pte bits on i386

[Ed L Cashin <ecashin@uga.edu>]

Hi.  This small patch documents that bits 9, 10, and 11 are unused by
the Linux kernel.  The IA-32 Intel Architecture Software Developer's
Manual says that these bits are available for programmer use.

I checked and couldn't see any use of these bits in the Linux kernel.
If I'm wrong and these bits *are* being used by the linux kernel, a
comment in include/asm-i386/pgtable.h would be helpful.  If they are
not, this patch confirms for developers that the kernel isn't using
these bits.


--- linux-2.6.0-test2/include/asm-i386/pgtable.h~	Sun Jul 27 13:06:27 2003
+++ linux-2.6.0-test2/include/asm-i386/pgtable.h	Thu Aug  7 11:16:36 2003
@@ -118,6 +118,9 @@
 #define _PAGE_DIRTY	0x040
 #define _PAGE_PSE	0x080	/* 4 MB (or 2MB) page, Pentium+, if present.. */
 #define _PAGE_GLOBAL	0x100	/* Global TLB entry PPro+ */
+#define _PAGE_UNUSED1	0x200	/* available for programmer */
+#define _PAGE_UNUSED2	0x400
+#define _PAGE_UNUSED3	0x800
 
 #define _PAGE_FILE	0x040	/* set:pagecache unset:swap */
 #define _PAGE_PROTNONE	0x080	/* If not present */


-- 
--Ed L Cashin            |   PGP public key:
  ecashin@uga.edu        |   http://noserose.net/e/pgp/