1 files changed, 8 insertions, 4 deletions

diff --git a/drivers/acpi/acpica/exregion.c b/drivers/acpi/acpica/exregion.c
index 1db2c0bfde0b..0a01e19c3190 100644
--- a/drivers/acpi/acpica/exregion.c
+++ b/drivers/acpi/acpica/exregion.c
@@ -142,9 +142,9 @@ acpi_ex_system_memory_space_handler(u32 function,
                 }
 
                 /*
-                 * Attempt to map from the requested address to the end of the region.
-                 * However, we will never map more than one page, nor will we cross
-                 * a page boundary.
+                 * October 2009: Attempt to map from the requested address to the
+                 * end of the region. However, we will never map more than one
+                 * page, nor will we cross a page boundary.
                  */
                 map_length = (acpi_size)
                     ((mem_info->address + mem_info->length) - address);
@@ -154,7 +154,11 @@ acpi_ex_system_memory_space_handler(u32 function,
                  * a page boundary, just map up to the page boundary, do not cross.
                  * On some systems, crossing a page boundary while mapping regions
                  * can cause warnings if the pages have different attributes
-                 * due to resource management
+                 * due to resource management.
+                 *
+                 * This has the added benefit of constraining a single mapping to
+                 * one page, which is similar to the original code that used a 4k
+                 * maximum window.
                  */
                 page_boundary_map_length =
                     ACPI_ROUND_UP(address, ACPI_DEFAULT_PAGE_SIZE) - address;