From: Mike Rapoport <rppt@xxxxxxxxxxxxx> Subject: arc: update comment about HIGHMEM implementation Arc does not use DISCONTIGMEM to implement high memory, update the comment describing how high memory works to reflect this. Link: https://lkml.kernel.org/r/20210608091316.3622-3-rppt@xxxxxxxxxx Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> Acked-by: Vineet Gupta <vgupta@xxxxxxxxxxxx> Acked-by: Arnd Bergmann <arnd@xxxxxxxx> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Matt Turner <mattst88@xxxxxxxxx> Cc: Richard Henderson <rth@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/arc/mm/init.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) --- a/arch/arc/mm/init.c~arc-update-comment-about-highmem-implementation +++ a/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); _
