From 499a5f1efa0b0ac56ec5d060412aed84ae68e63e Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 18 Dec 2009 16:05:51 +0000 Subject: 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 Cc: Linus Torvalds Cc: Andrew Morton LKML-Reference: <4B2BB66F0200007800026AD6@vpn.id2.novell.com> Signed-off-by: Ingo Molnar --- arch/x86/include/asm/fixmap.h | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) (limited to 'arch/x86/include/asm/fixmap.h') diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h index 14f9890eb495..635f03bb4995 100644 --- a/arch/x86/include/asm/fixmap.h +++ b/arch/x86/include/asm/fixmap.h @@ -118,14 +118,20 @@ enum fixed_addresses { * 256 temporary boot-time mappings, used by early_ioremap(), * before ioremap() is functional. * - * We round it up to the next 256 pages boundary so that we - * can have a single pgd entry and a single pte table: + * If necessary we round it up to the next 256 pages boundary so + * that we can have a single pgd entry and a single pte table: */ #define NR_FIX_BTMAPS 64 #define FIX_BTMAPS_SLOTS 4 - FIX_BTMAP_END = __end_of_permanent_fixed_addresses + 256 - - (__end_of_permanent_fixed_addresses & 255), - FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS*FIX_BTMAPS_SLOTS - 1, +#define TOTAL_FIX_BTMAPS (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS) + FIX_BTMAP_END = + (__end_of_permanent_fixed_addresses ^ + (__end_of_permanent_fixed_addresses + TOTAL_FIX_BTMAPS - 1)) & + -PTRS_PER_PTE + ? __end_of_permanent_fixed_addresses + TOTAL_FIX_BTMAPS - + (__end_of_permanent_fixed_addresses & (TOTAL_FIX_BTMAPS - 1)) + : __end_of_permanent_fixed_addresses, + FIX_BTMAP_BEGIN = FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1, #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT FIX_OHCI1394_BASE, #endif -- cgit v1.2.3