[PATCH v3 2/9] arc: update comment about HIGHMEM implementation

Mike Rapoport
2021-06-08T09:13:09Z

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@linux.ibm.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
---
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);
--
2.28.0