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authorLinus Torvalds <torvalds@linux-foundation.org>2016-07-27 03:56:45 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-27 03:56:45 +0300
commite663107fa1edda4d8a0d5b8ce704d71f8e27de43 (patch)
tree2ca367a9cdeb97ce613e792256b64831189af7b3 /Documentation
parent6453dbdda30428a3c56568c96fe70ea3612f07e2 (diff)
parent54d0b14ad7cc4ff3c710f092a93638f359c1b14b (diff)
downloadlinux-e663107fa1edda4d8a0d5b8ce704d71f8e27de43.tar.xz
Merge tag 'acpi-4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull ACPI updates from Rafael Wysocki: "The new feaures here are the support for ACPI overlays (allowing ACPI tables to be loaded at any time from EFI variables or via configfs) and the LPI (Low-Power Idle) support. Also notable is the ACPI-based NUMA support for ARM64. Apart from that we have two new drivers, for the DPTF (Dynamic Power and Thermal Framework) power participant device and for the Intel Broxton WhiskeyCove PMIC, some more PMIC-related changes, support for the Boot Error Record Table (BERT) in APEI and support for platform-initiated graceful shutdown. Plus two new pieces of documentation and usual assorted fixes and cleanups in quite a few places. Specifics: - Support for ACPI SSDT overlays allowing Secondary System Description Tables (SSDTs) to be loaded at any time from EFI variables or via configfs (Octavian Purdila, Mika Westerberg). - Support for the ACPI LPI (Low-Power Idle) feature introduced in ACPI 6.0 and allowing processor idle states to be represented in ACPI tables in a hierarchical way (with the help of Processor Container objects) and support for ACPI idle states management on ARM64, based on LPI (Sudeep Holla). - General improvements of ACPI support for NUMA and ARM64 support for ACPI-based NUMA (Hanjun Guo, David Daney, Robert Richter). - General improvements of the ACPI table upgrade mechanism and ARM64 support for that feature (Aleksey Makarov, Jon Masters). - Support for the Boot Error Record Table (BERT) in APEI and improvements of kernel messages printed by the error injection code (Huang Ying, Borislav Petkov). - New driver for the Intel Broxton WhiskeyCove PMIC operation region and support for the REGS operation region on Broxton, PMIC code cleanups (Bin Gao, Felipe Balbi, Paul Gortmaker). - New driver for the power participant device which is part of the Dynamic Power and Thermal Framework (DPTF) and DPTF-related code reorganization (Srinivas Pandruvada). - Support for the platform-initiated graceful shutdown feature introduced in ACPI 6.1 (Prashanth Prakash). - ACPI button driver update related to lid input events generated automatically on initialization and system resume that have been problematic for some time (Lv Zheng). - ACPI EC driver cleanups (Lv Zheng). - Documentation of the ACPICA release automation process and the in-kernel ACPI AML debugger (Lv Zheng). - New blacklist entry and two fixes for the ACPI backlight driver (Alex Hung, Arvind Yadav, Ralf Gerbig). - Cleanups of the ACPI pci_slot driver (Joe Perches, Paul Gortmaker). - ACPI CPPC code changes to make it more robust against possible defects in ACPI tables and new symbol definitions for PCC (Hoan Tran). - System reboot code modification to execute the ACPI _PTS (Prepare To Sleep) method in addition to _TTS (Ocean He). - ACPICA-related change to carry out lock ordering checks in ACPICA if ACPICA debug is enabled in the kernel (Lv Zheng). - Assorted minor fixes and cleanups (Andy Shevchenko, Baoquan He, Bhaktipriya Shridhar, Paul Gortmaker, Rafael Wysocki)" * tag 'acpi-4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (71 commits) ACPI: enable ACPI_PROCESSOR_IDLE on ARM64 arm64: add support for ACPI Low Power Idle(LPI) drivers: firmware: psci: initialise idle states using ACPI LPI cpuidle: introduce CPU_PM_CPU_IDLE_ENTER macro for ARM{32, 64} arm64: cpuidle: drop __init section marker to arm_cpuidle_init ACPI / processor_idle: Add support for Low Power Idle(LPI) states ACPI / processor_idle: introduce ACPI_PROCESSOR_CSTATE ACPI / DPTF: move int340x_thermal.c to the DPTF folder ACPI / DPTF: Add DPTF power participant driver ACPI / lpat: make it explicitly non-modular ACPI / dock: make dock explicitly non-modular ACPI / PCI: make pci_slot explicitly non-modular ACPI / PMIC: remove modular references from non-modular code ACPICA: Linux: Enable ACPI_MUTEX_DEBUG for Linux kernel ACPI: Rename configfs.c to acpi_configfs.c to prevent link error ACPI / debugger: Add AML debugger documentation ACPI: Add documentation describing ACPICA release automation ACPI: add support for loading SSDTs via configfs ACPI: add support for configfs efi / ACPI: load SSTDs from EFI variables ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/configfs-acpi36
-rw-r--r--Documentation/acpi/aml-debugger.txt66
-rw-r--r--Documentation/acpi/linuxized-acpica.txt262
-rw-r--r--Documentation/acpi/ssdt-overlays.txt172
-rw-r--r--Documentation/kernel-parameters.txt10
5 files changed, 546 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/configfs-acpi b/Documentation/ABI/testing/configfs-acpi
new file mode 100644
index 000000000000..4ab4e99aa863
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-acpi
@@ -0,0 +1,36 @@
+What: /config/acpi
+Date: July 2016
+KernelVersion: 4.8
+Contact: linux-acpi@vger.kernel.org
+Description:
+ This represents the ACPI subsystem entry point directory. It
+ contains sub-groups corresponding to ACPI configurable options.
+
+What: /config/acpi/table
+Date: July 2016
+KernelVersion: 4.8
+Description:
+
+ This group contains the configuration for user defined ACPI
+ tables. The attributes of a user define table are:
+
+ aml - a binary attribute that the user can use to
+ fill in the ACPI aml definitions. Once the aml
+ data is written to this file and the file is
+ closed the table will be loaded and ACPI devices
+ will be enumerated. To check if the operation is
+ successful the user must check the error code
+ for close(). If the operation is successful,
+ subsequent writes to this attribute will fail.
+
+ The rest of the attributes are read-only and are valid only
+ after the table has been loaded by filling the aml entry:
+
+ signature - ASCII table signature
+ length - length of table in bytes, including the header
+ revision - ACPI Specification minor version number
+ oem_id - ASCII OEM identification
+ oem_table_id - ASCII OEM table identification
+ oem_revision - OEM revision number
+ asl_compiler_id - ASCII ASL compiler vendor ID
+ asl_compiler_revision - ASL compiler version
diff --git a/Documentation/acpi/aml-debugger.txt b/Documentation/acpi/aml-debugger.txt
new file mode 100644
index 000000000000..5f62aa4a493b
--- /dev/null
+++ b/Documentation/acpi/aml-debugger.txt
@@ -0,0 +1,66 @@
+The AML Debugger
+
+Copyright (C) 2016, Intel Corporation
+Author: Lv Zheng <lv.zheng@intel.com>
+
+
+This document describes the usage of the AML debugger embedded in the Linux
+kernel.
+
+1. Build the debugger
+
+ The following kernel configuration items are required to enable the AML
+ debugger interface from the Linux kernel:
+
+ CONFIG_ACPI_DEBUGGER=y
+ CONFIG_ACPI_DEBUGGER_USER=m
+
+ The userspace utlities can be built from the kernel source tree using
+ the following commands:
+
+ $ cd tools
+ $ make acpi
+
+ The resultant userspace tool binary is then located at:
+
+ tools/acpi/power/acpi/acpidbg/acpidbg
+
+ It can be installed to system directories by running "make install" (as a
+ sufficiently privileged user).
+
+2. Start the userspace debugger interface
+
+ After booting the kernel with the debugger built-in, the debugger can be
+ started by using the following commands:
+
+ # mount -t debugfs none /sys/kernel/debug
+ # modprobe acpi_dbg
+ # tools/acpi/power/acpi/acpidbg/acpidbg
+
+ That spawns the interactive AML debugger environment where you can execute
+ debugger commands.
+
+ The commands are documented in the "ACPICA Overview and Programmer Reference"
+ that can be downloaded from
+
+ https://acpica.org/documentation
+
+ The detailed debugger commands reference is located in Chapter 12 "ACPICA
+ Debugger Reference". The "help" command can be used for a quick reference.
+
+3. Stop the userspace debugger interface
+
+ The interactive debugger interface can be closed by pressing Ctrl+C or using
+ the "quit" or "exit" commands. When finished, unload the module with:
+
+ # rmmod acpi_dbg
+
+ The module unloading may fail if there is an acpidbg instance running.
+
+4. Run the debugger in a script
+
+ It may be useful to run the AML debugger in a test script. "acpidbg" supports
+ this in a special "batch" mode. For example, the following command outputs
+ the entire ACPI namespace:
+
+ # acpidbg -b "namespace"
diff --git a/Documentation/acpi/linuxized-acpica.txt b/Documentation/acpi/linuxized-acpica.txt
new file mode 100644
index 000000000000..defe2eec5331
--- /dev/null
+++ b/Documentation/acpi/linuxized-acpica.txt
@@ -0,0 +1,262 @@
+Linuxized ACPICA - Introduction to ACPICA Release Automation
+
+Copyright (C) 2013-2016, Intel Corporation
+Author: Lv Zheng <lv.zheng@intel.com>
+
+
+Abstract:
+
+This document describes the ACPICA project and the relationship between
+ACPICA and Linux. It also describes how ACPICA code in drivers/acpi/acpica,
+include/acpi and tools/power/acpi is automatically updated to follow the
+upstream.
+
+
+1. ACPICA Project
+
+ The ACPI Component Architecture (ACPICA) project provides an operating
+ system (OS)-independent reference implementation of the Advanced
+ Configuration and Power Interface Specification (ACPI). It has been
+ adapted by various host OSes. By directly integrating ACPICA, Linux can
+ also benefit from the application experiences of ACPICA from other host
+ OSes.
+
+ The homepage of ACPICA project is: www.acpica.org, it is maintained and
+ supported by Intel Corporation.
+
+ The following figure depicts the Linux ACPI subystem where the ACPICA
+ adaptation is included:
+
+ +---------------------------------------------------------+
+ | |
+ | +---------------------------------------------------+ |
+ | | +------------------+ | |
+ | | | Table Management | | |
+ | | +------------------+ | |
+ | | +----------------------+ | |
+ | | | Namespace Management | | |
+ | | +----------------------+ | |
+ | | +------------------+ ACPICA Components | |
+ | | | Event Management | | |
+ | | +------------------+ | |
+ | | +---------------------+ | |
+ | | | Resource Management | | |
+ | | +---------------------+ | |
+ | | +---------------------+ | |
+ | | | Hardware Management | | |
+ | | +---------------------+ | |
+ | +---------------------------------------------------+ | |
+ | | | +------------------+ | | |
+ | | | | OS Service Layer | | | |
+ | | | +------------------+ | | |
+ | | +-------------------------------------------------|-+ |
+ | | +--------------------+ | |
+ | | | Device Enumeration | | |
+ | | +--------------------+ | |
+ | | +------------------+ | |
+ | | | Power Management | | |
+ | | +------------------+ Linux/ACPI Components | |
+ | | +--------------------+ | |
+ | | | Thermal Management | | |
+ | | +--------------------+ | |
+ | | +--------------------------+ | |
+ | | | Drivers for ACPI Devices | | |
+ | | +--------------------------+ | |
+ | | +--------+ | |
+ | | | ...... | | |
+ | | +--------+ | |
+ | +---------------------------------------------------+ |
+ | |
+ +---------------------------------------------------------+
+
+ Figure 1. Linux ACPI Software Components
+
+ NOTE:
+ A. OS Service Layer - Provided by Linux to offer OS dependent
+ implementation of the predefined ACPICA interfaces (acpi_os_*).
+ include/acpi/acpiosxf.h
+ drivers/acpi/osl.c
+ include/acpi/platform
+ include/asm/acenv.h
+ B. ACPICA Functionality - Released from ACPICA code base to offer
+ OS independent implementation of the ACPICA interfaces (acpi_*).
+ drivers/acpi/acpica
+ include/acpi/ac*.h
+ tools/power/acpi
+ C. Linux/ACPI Functionality - Providing Linux specific ACPI
+ functionality to the other Linux kernel subsystems and user space
+ programs.
+ drivers/acpi
+ include/linux/acpi.h
+ include/linux/acpi*.h
+ include/acpi
+ tools/power/acpi
+ D. Architecture Specific ACPICA/ACPI Functionalities - Provided by the
+ ACPI subsystem to offer architecture specific implementation of the
+ ACPI interfaces. They are Linux specific components and are out of
+ the scope of this document.
+ include/asm/acpi.h
+ include/asm/acpi*.h
+ arch/*/acpi
+
+2. ACPICA Release
+
+ The ACPICA project maintains its code base at the following repository URL:
+ https://github.com/acpica/acpica.git. As a rule, a release is made every
+ month.
+
+ As the coding style adopted by the ACPICA project is not acceptable by
+ Linux, there is a release process to convert the ACPICA git commits into
+ Linux patches. The patches generated by this process are referred to as
+ "linuxized ACPICA patches". The release process is carried out on a local
+ copy the ACPICA git repository. Each commit in the monthly release is
+ converted into a linuxized ACPICA patch. Together, they form the montly
+ ACPICA release patchset for the Linux ACPI community. This process is
+ illustrated in the following figure:
+
+ +-----------------------------+
+ | acpica / master (-) commits |
+ +-----------------------------+
+ /|\ |
+ | \|/
+ | /---------------------\ +----------------------+
+ | < Linuxize repo Utility >-->| old linuxized acpica |--+
+ | \---------------------/ +----------------------+ |
+ | |
+ /---------\ |
+ < git reset > \
+ \---------/ \
+ /|\ /+-+
+ | / |
+ +-----------------------------+ | |
+ | acpica / master (+) commits | | |
+ +-----------------------------+ | |
+ | | |
+ \|/ | |
+ /-----------------------\ +----------------------+ | |
+ < Linuxize repo Utilities >-->| new linuxized acpica |--+ |
+ \-----------------------/ +----------------------+ |
+ \|/
+ +--------------------------+ /----------------------\
+ | Linuxized ACPICA Patches |<----------------< Linuxize patch Utility >
+ +--------------------------+ \----------------------/
+ |
+ \|/
+ /---------------------------\
+ < Linux ACPI Community Review >
+ \---------------------------/
+ |
+ \|/
+ +-----------------------+ /------------------\ +----------------+
+ | linux-pm / linux-next |-->< Linux Merge Window >-->| linux / master |
+ +-----------------------+ \------------------/ +----------------+
+
+ Figure 2. ACPICA -> Linux Upstream Process
+
+ NOTE:
+ A. Linuxize Utilities - Provided by the ACPICA repository, including a
+ utility located in source/tools/acpisrc folder and a number of
+ scripts located in generate/linux folder.
+ B. acpica / master - "master" branch of the git repository at
+ <https://github.com/acpica/acpica.git>.
+ C. linux-pm / linux-next - "linux-next" branch of the git repository at
+ <http://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git>.
+ D. linux / master - "master" branch of the git repository at
+ <http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git>.
+
+ Before the linuxized ACPICA patches are sent to the Linux ACPI community
+ for review, there is a quality ensurance build test process to reduce
+ porting issues. Currently this build process only takes care of the
+ following kernel configuration options:
+ CONFIG_ACPI/CONFIG_ACPI_DEBUG/CONFIG_ACPI_DEBUGGER
+
+3. ACPICA Divergences
+
+ Ideally, all of the ACPICA commits should be converted into Linux patches
+ automatically without manual modifications, the "linux / master" tree should
+ contain the ACPICA code that exactly corresponds to the ACPICA code
+ contained in "new linuxized acpica" tree and it should be possible to run
+ the release process fully automatically.
+
+ As a matter of fact, however, there are source code differences between
+ the ACPICA code in Linux and the upstream ACPICA code, referred to as
+ "ACPICA Divergences".
+
+ The various sources of ACPICA divergences include:
+ 1. Legacy divergences - Before the current ACPICA release process was
+ established, there already had been divergences between Linux and
+ ACPICA. Over the past several years those divergences have been greatly
+ reduced, but there still are several ones and it takes time to figure
+ out the underlying reasons for their existence.
+ 2. Manual modifications - Any manual modification (eg. coding style fixes)
+ made directly in the Linux sources obviously hurts the ACPICA release
+ automation. Thus it is recommended to fix such issues in the ACPICA
+ upstream source code and generate the linuxized fix using the ACPICA
+ release utilities (please refer to Section 4 below for the details).
+ 3. Linux specific features - Sometimes it's impossible to use the
+ current ACPICA APIs to implement features required by the Linux kernel,
+ so Linux developers occasionaly have to change ACPICA code directly.
+ Those changes may not be acceptable by ACPICA upstream and in such cases
+ they are left as committed ACPICA divergences unless the ACPICA side can
+ implement new mechanisms as replacements for them.
+ 4. ACPICA release fixups - ACPICA only tests commits using a set of the
+ user space simulation utilies, thus the linuxized ACPICA patches may
+ break the Linux kernel, leaving us build/boot failures. In order to
+ avoid breaking Linux bisection, fixes are applied directly to the
+ linuxized ACPICA patches during the release process. When the release
+ fixups are backported to the upstream ACPICA sources, they must follow
+ the upstream ACPICA rules and so further modifications may appear.
+ That may result in the appearance of new divergences.
+ 5. Fast tracking of ACPICA commits - Some ACPICA commits are regression
+ fixes or stable-candidate material, so they are applied in advance with
+ respect to the ACPICA release process. If such commits are reverted or
+ rebased on the ACPICA side in order to offer better solutions, new ACPICA
+ divergences are generated.
+
+4. ACPICA Development
+
+ This paragraph guides Linux developers to use the ACPICA upstream release
+ utilities to obtain Linux patches corresponding to upstream ACPICA commits
+ before they become available from the ACPICA release process.
+
+ 1. Cherry-pick an ACPICA commit
+
+ First you need to git clone the ACPICA repository and the ACPICA change
+ you want to cherry pick must be committed into the local repository.
+
+ Then the gen-patch.sh command can help to cherry-pick an ACPICA commit
+ from the ACPICA local repository:
+
+ $ git clone https://github.com/acpica/acpica
+ $ cd acpica
+ $ generate/linux/gen-patch.sh -u [commit ID]
+
+ Here the commit ID is the ACPICA local repository commit ID you want to
+ cherry pick. It can be omitted if the commit is "HEAD".
+
+ 2. Cherry-pick recent ACPICA commits
+
+ Sometimes you need to rebase your code on top of the most recent ACPICA
+ changes that haven't been applied to Linux yet.
+
+ You can generate the ACPICA release series yourself and rebase your code on
+ top of the generated ACPICA release patches:
+
+ $ git clone https://github.com/acpica/acpica
+ $ cd acpica
+ $ generate/linux/make-patches.sh -u [commit ID]
+
+ The commit ID should be the last ACPICA commit accepted by Linux. Usually,
+ it is the commit modifying ACPI_CA_VERSION. It can be found by executing
+ "git blame source/include/acpixf.h" and referencing the line that contains
+ "ACPI_CA_VERSION".
+
+ 3. Inspect the current divergences
+
+ If you have local copies of both Linux and upstream ACPICA, you can generate
+ a diff file indicating the state of the current divergences:
+
+ # git clone https://github.com/acpica/acpica
+ # git clone http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
+ # cd acpica
+ # generate/linux/divergences.sh -s ../linux
diff --git a/Documentation/acpi/ssdt-overlays.txt b/Documentation/acpi/ssdt-overlays.txt
new file mode 100644
index 000000000000..5ae13f161ea2
--- /dev/null
+++ b/Documentation/acpi/ssdt-overlays.txt
@@ -0,0 +1,172 @@
+
+In order to support ACPI open-ended hardware configurations (e.g. development
+boards) we need a way to augment the ACPI configuration provided by the firmware
+image. A common example is connecting sensors on I2C / SPI buses on development
+boards.
+
+Although this can be accomplished by creating a kernel platform driver or
+recompiling the firmware image with updated ACPI tables, neither is practical:
+the former proliferates board specific kernel code while the latter requires
+access to firmware tools which are often not publicly available.
+
+Because ACPI supports external references in AML code a more practical
+way to augment firmware ACPI configuration is by dynamically loading
+user defined SSDT tables that contain the board specific information.
+
+For example, to enumerate a Bosch BMA222E accelerometer on the I2C bus of the
+Minnowboard MAX development board exposed via the LSE connector [1], the
+following ASL code can be used:
+
+DefinitionBlock ("minnowmax.aml", "SSDT", 1, "Vendor", "Accel", 0x00000003)
+{
+ External (\_SB.I2C6, DeviceObj)
+
+ Scope (\_SB.I2C6)
+ {
+ Device (STAC)
+ {
+ Name (_ADR, Zero)
+ Name (_HID, "BMA222E")
+
+ Method (_CRS, 0, Serialized)
+ {
+ Name (RBUF, ResourceTemplate ()
+ {
+ I2cSerialBus (0x0018, ControllerInitiated, 0x00061A80,
+ AddressingMode7Bit, "\\_SB.I2C6", 0x00,
+ ResourceConsumer, ,)
+ GpioInt (Edge, ActiveHigh, Exclusive, PullDown, 0x0000,
+ "\\_SB.GPO2", 0x00, ResourceConsumer, , )
+ { // Pin list
+ 0
+ }
+ })
+ Return (RBUF)
+ }
+ }
+ }
+}
+
+which can then be compiled to AML binary format:
+
+$ iasl minnowmax.asl
+
+Intel ACPI Component Architecture
+ASL Optimizing Compiler version 20140214-64 [Mar 29 2014]
+Copyright (c) 2000 - 2014 Intel Corporation
+
+ASL Input: minnomax.asl - 30 lines, 614 bytes, 7 keywords
+AML Output: minnowmax.aml - 165 bytes, 6 named objects, 1 executable opcodes
+
+[1] http://wiki.minnowboard.org/MinnowBoard_MAX#Low_Speed_Expansion_Connector_.28Top.29
+
+The resulting AML code can then be loaded by the kernel using one of the methods
+below.
+
+== Loading ACPI SSDTs from initrd ==
+
+This option allows loading of user defined SSDTs from initrd and it is useful
+when the system does not support EFI or when there is not enough EFI storage.
+
+It works in a similar way with initrd based ACPI tables override/upgrade: SSDT
+aml code must be placed in the first, uncompressed, initrd under the
+"kernel/firmware/acpi" path. Multiple files can be used and this will translate
+in loading multiple tables. Only SSDT and OEM tables are allowed. See
+initrd_table_override.txt for more details.
+
+Here is an example:
+
+# Add the raw ACPI tables to an uncompressed cpio archive.
+# They must be put into a /kernel/firmware/acpi directory inside the
+# cpio archive.
+# The uncompressed cpio archive must be the first.
+# Other, typically compressed cpio archives, must be
+# concatenated on top of the uncompressed one.
+mkdir -p kernel/firmware/acpi
+cp ssdt.aml kernel/firmware/acpi
+
+# Create the uncompressed cpio archive and concatenate the original initrd
+# on top:
+find kernel | cpio -H newc --create > /boot/instrumented_initrd
+cat /boot/initrd >>/boot/instrumented_initrd
+
+== Loading ACPI SSDTs from EFI variables ==
+
+This is the preferred method, when EFI is supported on the platform, because it
+allows a persistent, OS independent way of storing the user defined SSDTs. There
+is also work underway to implement EFI support for loading user defined SSDTs
+and using this method will make it easier to convert to the EFI loading
+mechanism when that will arrive.
+
+In order to load SSDTs from an EFI variable the efivar_ssdt kernel command line
+parameter can be used. The argument for the option is the variable name to
+use. If there are multiple variables with the same name but with different
+vendor GUIDs, all of them will be loaded.
+
+In order to store the AML code in an EFI variable the efivarfs filesystem can be
+used. It is enabled and mounted by default in /sys/firmware/efi/efivars in all
+recent distribution.
+
+Creating a new file in /sys/firmware/efi/efivars will automatically create a new
+EFI variable. Updating a file in /sys/firmware/efi/efivars will update the EFI
+variable. Please note that the file name needs to be specially formatted as
+"Name-GUID" and that the first 4 bytes in the file (little-endian format)
+represent the attributes of the EFI variable (see EFI_VARIABLE_MASK in
+include/linux/efi.h). Writing to the file must also be done with one write
+operation.
+
+For example, you can use the following bash script to create/update an EFI
+variable with the content from a given file:
+
+#!/bin/sh -e
+
+while ! [ -z "$1" ]; do
+ case "$1" in
+ "-f") filename="$2"; shift;;
+ "-g") guid="$2"; shift;;
+ *) name="$1";;
+ esac
+ shift
+done
+
+usage()
+{
+ echo "Syntax: ${0##*/} -f filename [ -g guid ] name"
+ exit 1
+}
+
+[ -n "$name" -a -f "$filename" ] || usage
+
+EFIVARFS="/sys/firmware/efi/efivars"
+
+[ -d "$EFIVARFS" ] || exit 2
+
+if stat -tf $EFIVARFS | grep -q -v de5e81e4; then
+ mount -t efivarfs none $EFIVARFS
+fi
+
+# try to pick up an existing GUID
+[ -n "$guid" ] || guid=$(find "$EFIVARFS" -name "$name-*" | head -n1 | cut -f2- -d-)
+
+# use a randomly generated GUID
+[ -n "$guid" ] || guid="$(cat /proc/sys/kernel/random/uuid)"
+
+# efivarfs expects all of the data in one write
+tmp=$(mktemp)
+/bin/echo -ne "\007\000\000\000" | cat - $filename > $tmp
+dd if=$tmp of="$EFIVARFS/$name-$guid" bs=$(stat -c %s $tmp)
+rm $tmp
+
+== Loading ACPI SSDTs from configfs ==
+
+This option allows loading of user defined SSDTs from userspace via the configfs
+interface. The CONFIG_ACPI_CONFIGFS option must be select and configfs must be
+mounted. In the following examples, we assume that configfs has been mounted in
+/config.
+
+New tables can be loading by creating new directories in /config/acpi/table/ and
+writing the SSDT aml code in the aml attribute:
+
+cd /config/acpi/table
+mkdir my_ssdt
+cat ~/ssdt.aml > my_ssdt/aml
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 118538b548f6..769db8399ac8 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -582,6 +582,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
bootmem_debug [KNL] Enable bootmem allocator debug messages.
+ bert_disable [ACPI]
+ Disable BERT OS support on buggy BIOSes.
+
bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
bttv.radio= Most important insmod options are available as
kernel args too.
@@ -1193,6 +1196,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Address Range Mirroring feature even if your box
doesn't support it.
+ efivar_ssdt= [EFI; X86] Name of an EFI variable that contains an SSDT
+ that is to be dynamically loaded by Linux. If there are
+ multiple variables with the same name but with different
+ vendor GUIDs, all of them will be loaded. See
+ Documentation/acpi/ssdt-overlays.txt for details.
+
+
eisa_irq_edge= [PARISC,HW]
See header of drivers/parisc/eisa.c.