Re: {PATCH] x86: print out initial max_pfn_mapped

From: H. Peter Anvin
Date: Mon Mar 16 2009 - 22:40:57 EST


Yinghai Lu wrote:
> Impact: more debug info
>
> check range that is mapped before init_memory_mapping().
> also make 64bit have max_pfn_mapped assigned before that calling
>
> Index: linux-2.6/arch/x86/mm/init.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/mm/init.c
> +++ linux-2.6/arch/x86/mm/init.c
> @@ -65,12 +65,11 @@ static void __init find_early_table_spac
> */
> #ifdef CONFIG_X86_32
> start = 0x7000;
> - e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
> - tables, PAGE_SIZE);
> -#else /* CONFIG_X86_64 */
> +#else
> start = 0x8000;
> - e820_table_start = find_e820_area(start, end, tables, PAGE_SIZE);
> #endif
> + e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
> + tables, PAGE_SIZE);
> if (e820_table_start == -1UL)
> panic("Cannot find space for the kernel page tables");
>

This doesn't seem to match anything anywhere in the description.
Furthermore, why do we even have a different starting address for
different architectures? If anything, this starting address is way too
low (hogging ZONE_DMA and all that...)

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

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