From: Andi Kleen Date: Wed, 11 Jan 2006 21:46:57 +0000 (+0100) Subject: [PATCH] x86_64: Allow kernel page tables upto the end of memory X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=6c5acd160a10c76e8debf4f8fa8256d7c914f290;p=openwrt%2Fstaging%2Fblogic.git [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 Signed-off-by: Linus Torvalds --- diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c index e93867850a4f..eca60125efc3 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< 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");