Re: [PATCH v2 2/9] arc: update comment about HIGHMEM implementation

[Vineet Gupta]

On 6/3/21 11:49 PM, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
>
> Arc does not use DISCONTIGMEM to implement high memory, update the comment
> describing how high memory works to reflect this.
>
> Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>

Acked-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>

Thx,
-Vineet

> ---
>   arch/arc/mm/init.c | 13 +++++--------
>   1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
> index e2ed355438c9..397a201adfe3 100644
> --- a/arch/arc/mm/init.c
> +++ b/arch/arc/mm/init.c
> @@ -139,16 +139,13 @@ void __init setup_arch_memory(void)
>   
>   #ifdef CONFIG_HIGHMEM
>   	/*
> -	 * Populate a new node with highmem
> -	 *
>   	 * On ARC (w/o PAE) HIGHMEM addresses are actually smaller (0 based)
> -	 * than addresses in normal ala low memory (0x8000_0000 based).
> +	 * than addresses in normal aka low memory (0x8000_0000 based).
>   	 * Even with PAE, the huge peripheral space hole would waste a lot of
> -	 * mem with single mem_map[]. This warrants a mem_map per region design.
> -	 * Thus HIGHMEM on ARC is imlemented with DISCONTIGMEM.
> -	 *
> -	 * DISCONTIGMEM in turns requires multiple nodes. node 0 above is
> -	 * populated with normal memory zone while node 1 only has highmem
> +	 * mem with single contiguous mem_map[].
> +	 * Thus when HIGHMEM on ARC is enabled the memory map corresponding
> +	 * to the hole is freed and ARC specific version of pfn_valid()
> +	 * handles the hole in the memory map.
>   	 */
>   #ifdef CONFIG_DISCONTIGMEM
>   	node_set_online(1);