Re: [PATCH v3 1/3] mm/hugetlb: Allow arch to override and call the weak function

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

On 07/27/2017 06:31 PM, Michal Hocko wrote:
> On Thu 27-07-17 11:48:26, Aneesh Kumar K.V wrote:
>> For ppc64, we want to call this function when we are not running as guest.
> 
> What does this mean?
> 

ppc64 guest (aka LPAR) support a different mechanism for hugetlb 
allocation/reservation. The LPAR management application called HMC can 
be used to reserve a set of hugepages and we pass the details of 
reserved pages via device tree to the guest. You can find the details in
htab_dt_scan_hugepage_blocks() . We do the memblock_reserve of the range 
and later in the boot sequence, we just add the reserved range to
huge_boot_pages.

For baremetal config (when we are not running as guest) we want to 
follow what other architecture does, that is look at the command line 
and do memblock allocation. Hence the need to call generic function 
__alloc_bootmem_huge_page() in that case.

I can add all these details in to the commit message if that makes it easy ?

-aneesh