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authorMike Rapoport <rppt@linux.ibm.com>2021-06-28 19:42:43 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-29 10:53:55 -0700
commite7793e53901b31a06db534679e77c0cdeab260a2 (patch)
tree40a3312efc91ff8fb4c093f5d48d2e0079a6b6be /arch/arc/mm
parentfdb7d9b7acd02f573ae4fc0c7772f6b5c6b1bad0 (diff)
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@kernel.org Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Vineet Gupta <vgupta@synopsys.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matt Turner <mattst88@gmail.com> Cc: Richard Henderson <rth@twiddle.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/arc/mm')
-rw-r--r--arch/arc/mm/init.c13
1 files 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);