--- /dev/null
+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
projects / cascardo / linux.git / commitdiff