How to apply a DSDT override

how-to-patch-dsdt.txt

# Instructions derived from: https://wiki.archlinux.org/index.php/DSDT

########################################################################
# Recompiling it yourself                                              #
# https://wiki.archlinux.org/index.php/DSDT#Recompiling_it_yourself    #
########################################################################

# Extract the binary ACPI tables
sudo cat /sys/firmware/acpi/tables/DSDT > dsdt.dat

# Disassemble the ACPI tables to a .dsl file
iasl -d dsdt.dat

# Attempt to create a hex AML table from the .dsl file
iasl -tc dsdt.dsl

# Manual step: Fix any compilation errors. A common source of errors is
# when iasl has to guess the type of unresolved external dependencies
# and fails to identify an external function that takes some arguments.

# Manual step: Increase the OEM version in the DSDT's DefinitionBlock.
# Otherwise, the kernel will not apply the modified ACPI table. For
# example, before increasing the OEM version:
#
#     DefinitionBlock ("DSDT.aml", "DSDT", 2, "INTEL ", "TEMPLATE", 0x00000000)
#
# After increasing the OEM version:
#
#     DefinitionBlock ("DSDT.aml", "DSDT", 2, "INTEL ", "TEMPLATE", 0x00000001)

# Create the hex AML table again after fixing all errors and increasing the OEM version
iasl -tc dsdt.dsl

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# Using modified code, using a cpio archive                            #
# https://wiki.archlinux.org/index.php/DSDT#Using_a_CPIO_archive       #
########################################################################

# This method requires the ACPI_TABLE_UPGRADE=y kernel config to be enabled!

# First, create the following folder structure
mkdir -p kernel/firmware/acpi

# Copy the patched DSDT into the newly-created kernel/firmware/acpi folder
cp dsdt.aml kernel/firmware/acpi

# Create a CPIO archive containing the patched DSDT
find kernel | cpio -H newc --create > acpi_override

# Copy the archive to the /boot directory
sudo cp acpi_override /boot

# Manual step: Configure the bootloader to load the newly-created CPIO
# archive as an initrd. The exact procedure depends on the bootloader.