On 2014/7/2 2:45, Yinghai Lu wrote: > On Tue, Jul 1, 2014 at 12:29 AM, Zhang Zhen <zhenzhang.zhang@xxxxxxxxxx> wrote: >> Hi, >> >> Recently We are testing stable kernel 3.10 on an ARM board. >> It failed to boot if we enabled CONFIG_SPARSEMEM config. > > Arm support 2 sockets and numa now? > ARM doesn't support numa until now. We have added memory hotplug feature on ARM arch. So we need to enable CONFIG_SPARSEMEM. >> 1. In mem_init() and show_mem() compare pfn instead of page just like the patch in attachement. >> 2. Enable CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER when enabled CONFIG_SPARSEMEM. >> >> QUESTION: >> >> I want to know why CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER depends on x86_64 ? > > That make memory allocation have less memory hole, from old bootmem bitmap > allocation stage. > > Maybe we don't need that anymore as we have memblock allocation that is more > smarter with alignment handling. > > Also allocating big size and use them block by block, could save some time on > searching on allocation function when memblock have lots of entries on > memory/reserved arrays. > > Thanks > > Yinghai > Hi, Yinghai Have you seen my patch ? If we enabled CONFIG_SPARSEMEM here in the patch need to enable CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER to guarantee the pages of different sections are continuous. So in my opinion, CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER doesn't need to depend on x86_64, which helps futher coding. If i'm wrong, please let me know ! Thanks for your comments! > -- 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>