[PATCH] arm: add comment about max_low_pfn/max_pfn

)


From: Russell King <rmk+lkml@arm.linux.org.uk>

Oddly, max_low_pfn/max_pfn end up being the number of pages in the system,
rather than the maximum PFN on ARM.  This doesn't seem to cause any problems,
so just add a note about it.

Signed-off-by: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 41156c5370f7..72a2b8cee319 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -223,6 +223,9 @@ find_memend_and_nodes(struct meminfo *mi, struct node_info *np)
          * This doesn't seem to be used by the Linux memory
          * manager any more.  If we can get rid of it, we
          * also get rid of some of the stuff above as well.
+         *
+         * Note: max_low_pfn and max_pfn reflect the number
+         * of _pages_ in the system, not the maximum PFN.
          */
         max_low_pfn = memend_pfn - O_PFN_DOWN(PHYS_OFFSET);
         max_pfn = memend_pfn - O_PFN_DOWN(PHYS_OFFSET);