Documentation: ACPI: move ssdt-overlays.txt to admin-guide/acpi and convert to reST (7fe19072) · Commits · 戴 / test

Documentation/admin-guide/acpi/index.rst

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		@@ -10,4 +10,5 @@ the Linux ACPI support.

		initrd_table_override
		dsdt-override
		ssdt-overlays
		cppc_sysfs

Documentation/acpi/ssdt-overlays.txt→Documentation/admin-guide/acpi/ssdt-overlays.rst

+180 −0

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		.. SPDX-License-Identifier: GPL-2.0

		=============
		SSDT Overlays
		=============

		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
		@@ -15,7 +20,7 @@ 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:
		following ASL code can be used::

		DefinitionBlock ("minnowmax.aml", "SSDT", 1, "Vendor", "Accel", 0x00000003)
		{
		@@ -47,7 +52,7 @@ DefinitionBlock ("minnowmax.aml", "SSDT", 1, "Vendor", "Accel", 0x00000003)
		}
		}

		which can then be compiled to AML binary format:
		which can then be compiled to AML binary format::

		$ iasl minnowmax.asl

		@@ -63,7 +68,8 @@ AML Output: minnowmax.aml - 165 bytes, 6 named objects, 1 executable opcodes
		The resulting AML code can then be loaded by the kernel using one of the methods
		below.

		== Loading ACPI SSDTs from initrd ==
		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.
		@@ -74,7 +80,7 @@ aml code must be placed in the first, uncompressed, initrd under the
		in loading multiple tables. Only SSDT and OEM tables are allowed. See
		initrd_table_override.txt for more details.

		Here is an example:
		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
		@@ -90,7 +96,8 @@ cp ssdt.aml kernel/firmware/acpi
		find kernel \| cpio -H newc --create > /boot/instrumented_initrd
		cat /boot/initrd >>/boot/instrumented_initrd

		== Loading ACPI SSDTs from EFI variables ==
		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
		@@ -116,7 +123,7 @@ 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:
		variable with the content from a given file::

		#!/bin/sh -e

		@@ -157,7 +164,8 @@ tmp=$(mktemp)
		dd if=$tmp of="$EFIVARFS/$name-$guid" bs=$(stat -c %s $tmp)
		rm $tmp

		== Loading ACPI SSDTs from configfs ==
		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
		@@ -165,7 +173,7 @@ 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:
		writing the SSDT aml code in the aml attribute::

		cd /config/acpi/table
		mkdir my_ssdt

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