Messages in this thread | | | Date | Fri, 3 Jul 2009 13:08:49 -0700 | Subject | Re: [Bug Fix]: Do 32-bit table calculations in pre-processor | From | Yinghai Lu <> |
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On Fri, Jul 3, 2009 at 1:07 PM, Yinghai Lu<yhlu.kernel@gmail.com> wrote: > On Fri, Jul 3, 2009 at 11:14 AM, Michael S. Zick<lkml@morethan.org> wrote: >> Here is one I have found useful in my VIA processor bug hunting: >> >> diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S >> index 3068388..2303d86 100644 >> --- a/arch/x86/kernel/head_32.S >> +++ b/arch/x86/kernel/head_32.S >> @@ -61,7 +61,7 @@ >> >> /* Enough space to fit pagetables for the low memory linear map */ >> MAPPING_BEYOND_END = \ >> - PAGE_TABLE_SIZE(((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT) << PAGE_SHIFT >> + PAGE_TABLE_SIZE((1<<20) - (__PAGE_OFFSET >> PAGE_SHIFT)) << PAGE_SHIFT >> >> /* >> * Worst-case size of the kernel mapping we need to make: >> >> = = = >> >> Before: >> >> #5 [0000010000 - 0000011000] PGTABLE ==> [0000010000 - 0000011000] >> #6 [0000011000 - 0000015000] BOOTMAP ==> [0000011000 - 0000015000] >> >> After: >> >> #5 [0000010000 - 000007d000] PGTABLE ==> [0000010000 - 000007d000] >> #6 [000007d000 - 0000081000] BOOTMAP ==> [000007d000 - 0000081000] >> > > that PGTABLE is from early resource. and it is filled by init_memory_mapping() > > it mean preallocated pgtable to MAPPING_BEYOND_END is small now after > patch. and init_memory_mapping try to get more. > > please send out whole dmesg. with and without your patch. it could > print out initial mapped before e820 allocation is involved for 32bit > printk(KERN_DEBUG "initial memory mapped : 0 - %08lx\n", > max_pfn_mapped<<PAGE_SHIFT); > > > your patch should be right. except to change that 12 to PAGE_SHIFT > mean
>> /* Enough space to fit pagetables for the low memory linear map */ >> MAPPING_BEYOND_END = \ >> - PAGE_TABLE_SIZE(((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT) << PAGE_SHIFT >> + PAGE_TABLE_SIZE((1<<(32 - PAGE_SHIFT)) - (__PAGE_OFFSET >> PAGE_SHIFT)) << PAGE_SHIFT
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