Hello tejun,
On 09/24/2013 08:27 PM, Tejun Heo wrote:
> On Tue, Sep 24, 2013 at 06:06:41PM +0800, Zhang Yanfei wrote:
>> +/**
>> + * memory_map_top_down - Map [map_start, map_end) top down
>> + * @map_start: start address of the target memory range
>> + * @map_end: end address of the target memory range
>> + *
>> + * This function will setup direct mapping for memory range [map_start, map_end)
>> + * in a heuristic way. In the beginning, step_size is small. The more memory we
>> + * map memory in the next loop.
>> + */
>
> The comment reads a bit weird to me. The step size is increased
> gradually but that really isn't really a heuristic and it doesn't
> mention mapping direction.
Ok, will change the words and add the comment of direction.
>
> ...
>> @@ -430,19 +430,13 @@ void __init init_mem_mapping(void)
>> min_pfn_mapped = real_end >> PAGE_SHIFT;
>> last_start = start = real_end;
>>
>> - /*
>> - * We start from the top (end of memory) and go to the bottom.
>> - * The memblock_find_in_range() gets us a block of RAM from the
>> - * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
>> - * for page table.
>> - */
>
> I think this comment should stay here with the variable names
> updated.
OK, agreed
>
>> - while (last_start > ISA_END_ADDRESS) {
>> + while (last_start > map_start) {
>> if (last_start > step_size) {
>> start = round_down(last_start - 1, step_size);
>> - if (start < ISA_END_ADDRESS)
>> - start = ISA_END_ADDRESS;
>> + if (start < map_start)
>> + start = map_start;
>> } else
>> - start = ISA_END_ADDRESS;
>> + start = map_start;
>> new_mapped_ram_size = init_range_memory_mapping(start,
>> last_start);
>> last_start = start;
>> @@ -453,8 +447,32 @@ void __init init_mem_mapping(void)
>> mapped_ram_size += new_mapped_ram_size;
>> }
>>
>> - if (real_end < end)
>> - init_range_memory_mapping(real_end, end);
>> + if (real_end < map_end)
>> + init_range_memory_mapping(real_end, map_end);
>> +}
>> +
>> +void __init init_mem_mapping(void)
>> +{
>> + unsigned long end;
>> +
>> + probe_page_size_mask();
>> +
>> +#ifdef CONFIG_X86_64
>> + end = max_pfn << PAGE_SHIFT;
>> +#else
>> + end = max_low_pfn << PAGE_SHIFT;
>> +#endif
>> +
>> + /* the ISA range is always mapped regardless of memory holes */
>> + init_memory_mapping(0, ISA_END_ADDRESS);
>> +
>> + /*
>> + * We start from the top (end of memory) and go to the bottom.
>> + * The memblock_find_in_range() gets us a block of RAM from the
>> + * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
>> + * for page table.
>> + */
>
> And just mention the range and direction in the comment here?
OK, agreed.
Thanks
>
>> + memory_map_top_down(ISA_END_ADDRESS, end);
>
> Thanks.
>
--
Thanks.
Zhang Yanfei
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