lamperez/custom_acpi_tables.md

## custom_acpi_tables.md

      
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              custom_acpi_tables.md
            
          
    ACPI DSDT/SSDT patching

These instructions are meant for a system with EFI, systemd-boot and deb based packages. Adjust them to your needs.
Reference:
https://www.kernel.org/doc/Documentation/acpi/initrd_table_override.txt
See also
https://github.com/lbschenkel/acer-sf314_43-acpi-patch
ACPICA tools:
https://acpica.org/downloads
sudo apt install acpica-tools

Option 1: DSDT, extract and modify the tables

Extract the acpi tables
mkdir acpi && cd acpi
sudo acpidump -b

Disassemble the tables
iasl -d dsdt.dat

Modify or patch the tables
vim dsdt.dsl

Assemble the custom tables
iasl -sa dsdt.dsl

Generate the cpio file for initrd
cd ..
mkdir -p kernel/firmware/acpi
cp acpi/dsdt.aml kernel/firmware/acpi/
find kernel | cpio -H newc --create > patched_acpi_tables.cpio

Grub does not require a cpio file, you can directly provide the dsl file.
Option 2: SSDT, create the tables

SSDT tables add missing features to the existing ACPI, without requiring disassembling. They are
created using the same tools and procedure.
Assemble the custom tables
iasl -sa ssdt.dsl

Generate the cpio file for initrd
cd ..
mkdir -p kernel/firmware/acpi
cp acpi/ssdt.aml kernel/firmware/acpi/
find kernel | cpio -H newc --create > patched_acpi_tables.cpio

Install the tables (systemd-boot)

Copy the cpio file with the custom tables where it can be addressed by the EFI boot
sudo mkdir /boot/efi/EFI/acpi
sudo cp patched_acpi_tables.cpio /boot/efi/EFI/acpi/

Edit the entry sudo vim /boot/efi/loader/entries/Pop_OS-current.conf
linux /EFI/...
initrd /EFI/acpi/patched_acpi_tables.cpio
initrd /EFI/Pop_OS-.../initrd.img
options ...