From af1ae78abb324def77ba0c6c3a7c7678fb5cebbe Mon Sep 17 00:00:00 2001 From: Al Stone Date: Fri, 17 Jan 2014 11:51:30 -0700 Subject: [PATCH] ACPI: introduce CONFIG_ACPI_REDUCED_HARDWARE_ONLY ACPI hardware reduced mode exists to allow newer platforms to use a simpler form of ACPI that does not require supporting legacy versions of the specification and their associated hardware. This mode was introduced in the ACPI 5.0 specification. The ACPI hardware reduced mode is supposed to be used on systems having the HW_REDUCED_ACPI flag set in the FADT. ACPICA checks that flag to determine whether or not it should work in the HW reduced mode and there are pieces of code in it that will never be used in that case. Since some architecutres will always use the ACPI HW reduced mode, it doesn't make sense for them to ever compile support for anything else. Thus, they should set the flag ACPI_REDUCED_HARDWARE to TRUE in the ACPICA source. To enable them to do that, introduce a new kernel configuration option, CONFIG_ACPI_REDUCED_HARDWARE_ONLY, that will cause the ACPICA's ACPI_REDUCED_HARDWARE flag to be TRUE when set. Introducing this configuration item is based on suggestions from Lv Zheng saying that this does not belong in ACPICA, but rather to the Linux kernel itself. References: http://www.spinics.net/lists/linux-acpi/msg46369.html Signed-off-by: Hanjun Guo Signed-off-by: Al Stone [rjw: Subject and changelog] Signed-off-by: Rafael J. Wysocki --- drivers/acpi/Kconfig | 13 +++++++++++++ include/acpi/platform/aclinux.h | 6 ++++++ 2 files changed, 19 insertions(+) diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 4770de5707b9..9fd6a7a124c0 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -343,6 +343,19 @@ config ACPI_BGRT data from the firmware boot splash. It will appear under /sys/firmware/acpi/bgrt/ . +config ACPI_REDUCED_HARDWARE_ONLY + bool "Hardware-reduced ACPI support only" if EXPERT + def_bool n + depends on ACPI + help + This config item changes the way the ACPI code is built. When this + option is selected, the kernel will use a specialized version of + ACPICA that ONLY supports the ACPI "reduced hardware" mode. The + resulting kernel will be smaller but it will also be restricted to + running in ACPI reduced hardware mode ONLY. + + If you are unsure what to do, do not enable this option. + source "drivers/acpi/apei/Kconfig" config ACPI_EXTLOG diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h index 008aa287c7a9..30c9a7c1af88 100644 --- a/include/acpi/platform/aclinux.h +++ b/include/acpi/platform/aclinux.h @@ -52,6 +52,12 @@ #ifdef __KERNEL__ +/* Compile for reduced hardware mode only with this kernel config */ + +#ifdef CONFIG_ACPI_REDUCED_HARDWARE_ONLY +#define ACPI_REDUCED_HARDWARE 1 +#endif + #include #include #include -- 2.20.1