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[PATCH] x86_64: Allow kernel page tables upto the end of memory

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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>
This commit is contained in:
Andi Kleen 2006-01-11 22:46:57 +01:00 committed by Linus Torvalds
parent 0a9c3ee769
commit 6c5acd160a
1 changed files with 14 additions and 2 deletions
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16
arch/x86_64/mm/init.c
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@ -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");