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-rw-r--r--arch/x86/kernel/head_32.S13
1 files changed, 10 insertions, 3 deletions
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 53eeb226657c..7e429c99c728 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -62,9 +62,16 @@
62#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD) 62#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
63#endif 63#endif
64 64
65/* Number of possible pages in the lowmem region */ 65/*
66LOWMEM_PAGES = (((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT) 66 * Number of possible pages in the lowmem region.
67 67 *
68 * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a
69 * gas warning about overflowing shift count when gas has been compiled
70 * with only a host target support using a 32-bit type for internal
71 * representation.
72 */
73LOWMEM_PAGES = (((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT)
74
68/* Enough space to fit pagetables for the low memory linear map */ 75/* Enough space to fit pagetables for the low memory linear map */
69MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT 76MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT
70 77