lkml.org 
[lkml]   [2009]   [Jul]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [Bug Fix]: Do 32-bit table calculations in pre-processor
    From
    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

    YH
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2009-07-03 22:09    [W:3.355 / U:0.420 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site