Messages in this thread | | | Date | Fri, 3 Jul 2009 13:07:04 -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 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
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