Comment 1 for bug 1222861

after a long discussion with Robert Moore and Lv Zheng form intel (they are ACPICA maintainer), they agreed to introduce a kernel config for the ACPI_HARDWARE_REDUCED macro, some thing like:

From b10bc1d2f9a3ff09abfb6990412aa1cf62d56937 Mon Sep 17 00:00:00 2001
From: Hanjun Guo <email address hidden>
Date: Wed, 18 Sep 2013 17:19:23 +0800
Subject: [PATCH] ACPI: Introduce CONFIG_ACPI_REDUCED_HARDWARE to enable
 reduced hardware

If we want to enable reduced hardware ACPI on some platform (such as ARM),
we need to modify the kernel code and set ACPI_REDUCED_HARDWARE to TRUE.

This is not reasonable, so introduce a kernel config to enable it, and
no need for kernel modification when we use hardware-reduced ACPI.

Signed-off-by: Hanjun Guo <email address hidden>
---
 drivers/acpi/Kconfig | 8 ++++++++
 include/acpi/acconfig.h | 4 ++++
 2 files changed, 12 insertions(+)

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 0d7f6eb..1232a7b 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -413,6 +413,14 @@ config ACPI_BGRT
          data from the firmware boot splash. It will appear under
          /sys/firmware/acpi/bgrt/ .

+config ACPI_REDUCED_HARDWARE
+ bool "Hardware-reduced ACPI support"
+ depends on ARM || ARM64
+ help
+ This config adds support for Hardware-reduced ACPI. When this option
+ is selected, will generate a specialized version of ACPICA that ONLY
+ supports the ACPI 5.0 "reduced hardware".
+
 source "drivers/acpi/apei/Kconfig"

 endif # ACPI
diff --git a/include/acpi/acconfig.h b/include/acpi/acconfig.h
index 1c16f82..15254f5 100644
--- a/include/acpi/acconfig.h
+++ b/include/acpi/acconfig.h
@@ -100,7 +100,11 @@
  * ACPI PM timer
  * FACS table (Waking vectors and Global Lock)
  */
+#ifdef CONFIG_ACPI_REDUCED_HARDWARE
+#define ACPI_REDUCED_HARDWARE TRUE
+#else
 #define ACPI_REDUCED_HARDWARE FALSE
+#endif /* CONFIG_ACPI_REDUCED_HARDWARE */

 /******************************************************************************
  *
-- 1.7.9.5