From 6c5acd160a10c76e8debf4f8fa8256d7c914f290 Mon Sep 17 00:00:00 2001
From: Andi Kleen <ak@suse.de>
Date: Wed, 11 Jan 2006 22:46:57 +0100
Subject: [PATCH] [PATCH] x86_64: Allow kernel page tables upto the end of
memory
Previously they would be only allocated before the kernel text at
1MB. This limited the maximum supported memory to 128GB.
Now allow the e820 allocator to put them everywhere. Try
to put them beyond any DMA zones to avoid filling them up.
This should free some GFP_DMA memory compared to earlier kernels.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
arch/x86_64/mm/init.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index e93867850a4f3..eca60125efc3b 100644
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -255,14 +255,26 @@ static void __init phys_pud_init(pud_t *pud, unsigned long address, unsigned lon
static void __init find_early_table_space(unsigned long end)
{
- unsigned long puds, pmds, tables;
+ unsigned long puds, pmds, tables, start;
puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
tables = round_up(puds * sizeof(pud_t), PAGE_SIZE) +
round_up(pmds * sizeof(pmd_t), PAGE_SIZE);
- table_start = find_e820_area(0x8000, __pa_symbol(&_text), tables);
+ /* Put page tables beyond the DMA zones if possible.
+ RED-PEN might be better to spread them out more over
+ memory to avoid hotspots */
+ if (end > MAX_DMA32_PFN<<PAGE_SHIFT)
+ start = MAX_DMA32_PFN << PAGE_SHIFT;
+ else if (end > MAX_DMA_PFN << PAGE_SHIFT)
+ start = MAX_DMA_PFN << PAGE_SHIFT;
+ else
+ start = 0x8000;
+
+ table_start = find_e820_area(start, end, tables);
+ if (table_start == -1)
+ table_start = find_e820_area(0x8000, end, tables);
if (table_start == -1UL)
panic("Cannot find space for the kernel page tables");
--
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