x86: ifdef 32-bit and 64-bit pfn setup in init_memory_mapping()
Impact: cleanup
To reduce the diff between the 32-bit and 64-bit versions of
init_memory_mapping(), ifdef configuration specific pfn setup
code in the function.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <1236257708-27269-11-git-send-email-penberg@cs.helsinki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 5ecb23a..d99bc6a 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -741,8 +741,22 @@
/* head if not big page alignment ? */
start_pfn = start >> PAGE_SHIFT;
pos = start_pfn << PAGE_SHIFT;
+#ifdef CONFIG_X86_32
+ /*
+ * Don't use a large page for the first 2/4MB of memory
+ * because there are often fixed size MTRRs in there
+ * and overlapping MTRRs into large pages can cause
+ * slowdowns.
+ */
+ if (pos == 0)
+ end_pfn = 1<<(PMD_SHIFT - PAGE_SHIFT);
+ else
+ end_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
+ << (PMD_SHIFT - PAGE_SHIFT);
+#else /* CONFIG_X86_64 */
end_pfn = ((pos + (PMD_SIZE - 1)) >> PMD_SHIFT)
<< (PMD_SHIFT - PAGE_SHIFT);
+#endif
if (end_pfn > (end >> PAGE_SHIFT))
end_pfn = end >> PAGE_SHIFT;
if (start_pfn < end_pfn) {
@@ -753,16 +767,22 @@
/* big page (2M) range */
start_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
<< (PMD_SHIFT - PAGE_SHIFT);
+#ifdef CONFIG_X86_32
+ end_pfn = (end>>PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
+#else /* CONFIG_X86_64 */
end_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
<< (PUD_SHIFT - PAGE_SHIFT);
if (end_pfn > ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT)))
end_pfn = ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT));
+#endif
+
if (start_pfn < end_pfn) {
nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
page_size_mask & (1<<PG_LEVEL_2M));
pos = end_pfn << PAGE_SHIFT;
}
+#ifdef CONFIG_X86_64
/* big page (1G) range */
start_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
<< (PUD_SHIFT - PAGE_SHIFT);
@@ -783,6 +803,7 @@
page_size_mask & (1<<PG_LEVEL_2M));
pos = end_pfn << PAGE_SHIFT;
}
+#endif
/* tail is not big page (2M) alignment */
start_pfn = pos>>PAGE_SHIFT;