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authorJan Beulich <JBeulich@novell.com>2009-12-18 16:05:51 +0000
committerIngo Molnar <mingo@elte.hu>2009-12-30 11:57:30 +0100
commit499a5f1efa0b0ac56ec5d060412aed84ae68e63e (patch)
tree4e6bd3e2ed34b4b0736d89203e8f6212106a1f4f /arch/x86/mm/ioremap.c
parent39d997b514e12d5aff0dca206eb8996b3957927e (diff)
downloadop-kernel-dev-499a5f1efa0b0ac56ec5d060412aed84ae68e63e.zip
op-kernel-dev-499a5f1efa0b0ac56ec5d060412aed84ae68e63e.tar.gz
x86: Lift restriction on the location of FIX_BTMAP_*
The early ioremap fixmap entries cover half (or for 32-bit non-PAE, a quarter) of a page table, yet they got uncondtitionally aligned so far to a 256-entry boundary. This is not necessary if the range of page table entries anyway falls into a single page table. This buys back, for (theoretically) 50% of all configurations (25% of all non-PAE ones), at least some of the lowmem necessarily lost with commit e621bd18958ef5dbace3129ebe17a0a475e127d9. Signed-off-by: Jan Beulich <jbeulich@novell.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> LKML-Reference: <4B2BB66F0200007800026AD6@vpn.id2.novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/mm/ioremap.c')
-rw-r--r--arch/x86/mm/ioremap.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index c246d25..03c75ff 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -422,6 +422,10 @@ void __init early_ioremap_init(void)
* The boot-ioremap range spans multiple pmds, for which
* we are not prepared:
*/
+#define __FIXADDR_TOP (-PAGE_SIZE)
+ BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT)
+ != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT));
+#undef __FIXADDR_TOP
if (pmd != early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END))) {
WARN_ON(1);
printk(KERN_WARNING "pmd %p != %p\n",
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