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SubjectRe: [PATCH -v2 13/13] x86, 64bit: Map first 1M ram early before memblock_x86_fill()
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On Sun, Sep 2, 2012 at 10:46 AM, Yinghai Lu <yinghai@kernel.org> wrote:
> This one intend to fix bugs:
> when efi booting have too many memmap entries, will need to double memblock
> memory array or reserved array.

Okay, why do we need to do that?

> +RESERVE_BRK(early_pgt_alloc, 65536);

What is this needed for?

> +void __init early_init_mem_mapping(void)
> +{
> + unsigned long tables;
> + phys_addr_t base;
> + unsigned long start = 0, end = ISA_END_ADDRESS;
> +
> + probe_page_size_mask();
> +
> + if (max_pfn_mapped)
> + return;

I find this confusing - what is this protecting for? Why is
'max_pfn_mapped' set when someone calls early_init_mem_mappings()?

Side note: we have multiple "pfn_mapped" globals and it's not at all
obvious to me what the semantics for them are. Maybe adding a comment
or two in arch/x86/include/asm/page_types.h would help.

> +
> + tables = calculate_table_space_size(start, end);
> + base = __pa(extend_brk(tables, PAGE_SIZE));
> +


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