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d912b53b | 1 | Ed L Cashin <ecashin@uga.edu> writes: |
2 | ||
3 | > Hi. This small patch documents that bits 9, 10, and 11 are unused by | |
4 | > the Linux kernel. The IA-32 Intel Architecture Software Developer's | |
5 | > Manual says that these bits are available for programmer use. | |
6 | > | |
7 | > I checked and couldn't see any use of these bits in the Linux kernel. | |
8 | > If I'm wrong and these bits *are* being used by the linux kernel, a | |
9 | > comment in include/asm-i386/pgtable.h would be helpful. If they are | |
10 | > not, this patch confirms for developers that the kernel isn't using | |
11 | > these bits. | |
12 | ||
13 | For consistency, there should be the analogous _PAGE_BIT_XXX macros, | |
14 | too, so here's a replacement patch that has those. | |
15 | ||
16 | ||
17 | ||
18 | --- trivial-2.6.0-test5-bk10/include/asm-i386/pgtable.h.orig 2003-09-24 12:27:18.000000000 +1000 | |
19 | +++ trivial-2.6.0-test5-bk10/include/asm-i386/pgtable.h 2003-09-24 12:27:18.000000000 +1000 | |
20 | @@ -108,6 +108,9 @@ | |
21 | #define _PAGE_BIT_DIRTY 6 | |
22 | #define _PAGE_BIT_PSE 7 /* 4 MB (or 2MB) page, Pentium+, if present.. */ | |
23 | #define _PAGE_BIT_GLOBAL 8 /* Global TLB entry PPro+ */ | |
24 | +#define _PAGE_BIT_UNUSED1 9 /* available for programmer */ | |
25 | +#define _PAGE_BIT_UNUSED2 10 | |
26 | +#define _PAGE_BIT_UNUSED3 11 | |
27 | ||
28 | #define _PAGE_PRESENT 0x001 | |
29 | #define _PAGE_RW 0x002 | |
30 | @@ -118,6 +121,9 @@ | |
31 | #define _PAGE_DIRTY 0x040 | |
32 | #define _PAGE_PSE 0x080 /* 4 MB (or 2MB) page, Pentium+, if present.. */ | |
33 | #define _PAGE_GLOBAL 0x100 /* Global TLB entry PPro+ */ | |
34 | +#define _PAGE_UNUSED1 0x200 /* available for programmer */ | |
35 | +#define _PAGE_UNUSED2 0x400 | |
36 | +#define _PAGE_UNUSED3 0x800 | |
37 | ||
38 | #define _PAGE_FILE 0x040 /* set:pagecache unset:swap */ | |
39 | #define _PAGE_PROTNONE 0x080 /* If not present */ |