Hi,

Recently We are testing stable kernel 3.10 on an ARM board.
It failed to boot if we enabled CONFIG_SPARSEMEM config.

Through the analysis, we found that mem_init() assumes the pages of different
sections are continuous.

But the truth is the pages of different sections are not continuous when
CONFIG_SPARSEMEM is enabled.

So now we have two ways to boot up when we enabled CONFIG_SPARSEMEM on an arm board.

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 ?

Whether we can enable it on an ARM board ?

Or any other better solution ?


Best regards!