ACPICA: Truncate I/O addresses to 16 bits for Windows compatibility

This feature is optional and is enabled if the BIOS requests any
Windows OSI strings. It can also be enabled by the host OS.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/nsinit.c b/drivers/acpi/acpica/nsinit.c
index 9bd6f050f29..4e5272c313e 100644
--- a/drivers/acpi/acpica/nsinit.c
+++ b/drivers/acpi/acpica/nsinit.c
@@ -193,6 +193,15 @@ acpi_status acpi_ns_initialize_devices(void)
                                         acpi_ns_init_one_device, NULL, &info,
                                         NULL);
 
+        /*
+         * Any _OSI requests should be completed by now. If the BIOS has
+         * requested any Windows OSI strings, we will always truncate
+         * I/O addresses to 16 bits -- for Windows compatibility.
+         */
+        if (acpi_gbl_osi_data >= ACPI_OSI_WIN_2000) {
+                acpi_gbl_truncate_io_addresses = TRUE;
+        }
+
         ACPI_FREE(info.evaluate_info);
         if (ACPI_FAILURE(status)) {
                 goto error_exit;