On 04/24/2013 04:40 PM, Simon Jeons wrote: > > I see in memblock_trim_memory(): start = round_up(orig_start, align); > here align is PAGE_SIZE, so the dump of zone ranges in my machine is [ > 0.000000] DMA [mem 0x00001000-0x00ffffff]. Why PFN 0 is not > used? just for align? > PFN 0 contains the real-mode interrupt vector table and BIOS data area, so we just reserve it. Avoids issues with zero being special, too. -hpa -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>