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Install KAIT2EN modules and apps

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Install.sh

Install.sh will install DKMS modules, scripts and apps by running a stack of sub-scripts.

Run this command from the KAIT2EN repository root on your Fedora system:

sudo bash ./scripts/fedora/install.sh

This runs all required installation steps in order.

It will take a few minutes to compile the modules and apps against the kernel. Stay around to enter needed confirmations while the script is running. Please reboot after the script completed without errors.

sudo reboot

Modules

KAIT2EN renames drivers it maintains because the original Fedora and older T2 Linux drivers must be blocked during boot. If KAIT2EN used the same module names, the kernel arguments that block the original drivers would also block our replacements.

The new names also make logs, lsmod, DKMS state and bug reports easier to read. The list below shows which modules are blacklisted and replaced by their KAIT2EN equivalents:

T2 Linux driver → KAIT2EN driver

hid_magicmouse → hid_t2magicmouse contains Asahi trackpad patches

apple-bce → t2bce_<module> T2 bridge, audio, VHCI devices, DMA and mailbox

appletbdrm → t2bdrm Touch Bar display DRM device

apple_gmux → t2gmux GMUX handling on dual-GPU Macs

hid_apple → t2hid Apple HID quirks for internal input devices

apple_mfi_fastcharge → t2mfi_fastcharge fast charging on Apple USB controllers.

applesmc → t2smc battery charge limit, hwmon sensors and RTC through the T2 SMC.

hid_appletb_bl → t2touchbar_bl Touch Bar backlight handling.

hid_appletb_kbd → t2touchbar_kbd Touch Bar keyboard mode handling.

Scripts and services

Below you will find all scripts and apps that are installed when running install.sh. You dont't need to run them manually. You can do that when you only want to install updates partially. Also devs please note how to enable debugging on the very bottom of this document.

Automatic ACPI firmware fixes

Before rebuilding the initramfs, the installer checks for two known ACPI problems on Intel T2 Macs:

  • CpuSSDT tries to load SSDT sub-tables already loaded by Linux. The fix pre-initializes \SDTL so GCAP skips them and avoids AE_ALREADY_EXISTS.
  • a DSDT _OSC buffer overflow reported as AE_AML_BUFFER_LIMIT

The autofix builds the matching override from the running Mac's ACPI tables and validates it with iasl. A table is not installed if validation fails.

Successful overrides and their Dracut configuration are written to:

/usr/local/lib/firmware/acpi/*.aml
/etc/dracut.conf.d/t2-acpi-fix.conf

Files replaced during deployment are backed up below /var/backups/t2-acpi-fix/<timestamp>/.

After rebooting, both commands should return no matching kernel messages for a successfully applied fix:

journalctl -b0 -k --grep=AE_AML_BUFFER_LIMIT
journalctl -b0 -k --grep='Marking method'

Apple T2 Audio DSP

This is a fork of Lemmyg's Apple-T2-Audio-DSP repo). Leave him a proper GitHub star for his work. We adapted it to make it work on Fedora. Most FIR files originate from lemmyg's t2-apple-audio-dsp; the MacBook Pro 15,1 FIRs were generated from UMIK-1 measurements of that model by deqrocks.

This is PipeWire/WirePlumber DSP graphs and FIR files for Apple T2 audio. The profiles in firs/ are installed by scripts/fedora/install-dsp.sh.

Supported profiles:

  • MacBookPro16,1
  • MacBookPro16,4
  • MacBookAir9,1
  • MacBookPro15,1

The installer copies the matching files to:

/usr/share/kait2en/audio-dsp/<profile>/

It generates a WirePlumber configuration at:

/etc/wireplumber/wireplumber.conf.d/51-kait2en-t2-dsp.conf

The graph target is rewritten at install time to match the detected Apple T2 audio PCI device and KAIT2EN UCM sink/source names.

Required Fedora packages are installed by install-dsp.sh, not by the common dependency installer:

  • pipewire
  • pipewire-pulseaudio
  • wireplumber
  • pipewire-module-filter-chain-lv2
  • lv2-bankstown
  • lv2-triforce
  • lsp-plugins-lv2
  • lv2-swh-plugins

Suspend helper

The installer creates and enables kait2en-suspend.service. It runs before suspend and after resume. The helper detects the local hardware and only applies fixes that match the machine.

The suspend helper is installed as:

/etc/systemd/system/kait2en-suspend.service # systemd service to run the .sh below
/usr/local/libexec/kait2en/kait2en-suspend.sh # actual script

The source files in this repository are:

systemd/kait2en-suspend.service
scripts/fedora/kait2en-suspend.sh
scripts/fedora/install-suspend-service.sh

The service runs before sleep.target and again after resume. On affected dual-GPU MacBook Pro models it unloads amdgpu before suspend and loads it again after resume. On BCM4377 systems it unloads brcmfmac_wcc, brcmfmac and hci_bcm4377 before suspend, then loads the modules again after resume.

If the helper does not detect matching hardware, it does not unload anything.

T2 CDC-NCM debug interface helper

The installer installs a udev rule that renames the internal Apple T2 CDC-NCM interface to t2_ncm and tells NetworkManager to ignore it. A separate oneshot systemd service is started for that device and keeps it down. When you remove this, NetworkManager will annoy you with notifications about failed connections from USB-Ethernet, which actually is a debugging interface and not meant to be used for intranet/internet connections.

As an alternative, you can disable USB-Ethernet auto connect in network settings.

The T2 CDC-NCM debug interface helper is installed as:

/etc/systemd/system/kait2en-t2-ncm-down.service # systemd service triggered for the debug interface
/usr/local/libexec/kait2en/kait2en-t2-ncm-down.sh # actual script
/etc/udev/rules.d/90-kait2en-t2-network.rules # NetworkManager exclusion

The source files in this repository are:

systemd/kait2en-t2-ncm-down.service
scripts/fedora/kait2en-t2-ncm-down.sh
scripts/fedora/install-t2-ncm-debug-service.sh
scripts/fedora/install-networkmanager-rules.sh

The udev rule detects the internal Apple T2 CDC-NCM interface by USB vendor and product ID plus the cdc_ncm driver, renames it to t2_ncm, marks it unmanaged for NetworkManager and asks systemd to start the helper service for that device. The helper then forces t2_ncm back down for a short retry window so late boot activity does not leave the debug interface up.

T2-specific applications

The installer installs the required KAIT2EN apps:

  • t2-fan-control # Adjustable fan curves with GUI
  • t2-smc-control # Battery charge limit and SMC sensors in a GUI
  • react-drm # Touchbar daemon - only on Touch Bar Macs

t2-fan-control and t2-smc-control can be found in the GNOME-App-Drawer after installation is finished.

t2-fan-control installs:

  • Binary: /usr/local/bin/t2-fancontrol-gtk
  • Desktop file: /usr/local/share/applications/org.t2fancontrol.gtk.desktop
  • Icon: /usr/local/share/icons/hicolor/scalable/apps/org.t2fancontrol.gtk.svg
  • systemd service: /usr/local/lib/systemd/system/t2-fancontrol.service
  • The service is enabled with systemctl enable --now t2-fancontrol.service

t2-smc-control installs:

  • Binary: /usr/local/bin/t2-smc-control
  • Desktop file: /usr/local/share/applications/org.t2smccontrol.gtk.desktop
  • Icon: /usr/local/share/icons/hicolor/scalable/apps/org.t2smccontrol.gtk.svg
  • systemd service: /usr/local/lib/systemd/system/kait2en-t2-smc-charge-limit.service
  • Config file, after the first saved limit: /etc/t2-smc-control/config.txt
  • The service is enabled with systemctl enable kait2en-t2-smc-charge-limit.service

When the GUI successfully sets the battery charge limit, it saves the selected value in /etc/t2-smc-control/config.txt. On later boots, kait2en-t2-smc-charge-limit.service restores that value through the t2smc hwmon battery_charge_limit attribute.

react-drm installs:

  • Source and build directory: $HOME/react-drm for the user who invoked sudo
  • udev rule: /etc/udev/rules.d/99-react-drm.rules
  • User service: $HOME/.config/systemd/user/react-drm.service
  • The service is enabled with systemctl --user enable --now react-drm.service
  • Service WorkingDirectory: $HOME/react-drm/linux-touchbar-control-center
  • Service ExecStart: node $HOME/react-drm/linux-touchbar-control-center/dist/index.js

The installer builds t2-fan-control and t2-smc-control as the user who invoked sudo, then installs them system-wide below /usr/local. react-drm is copied into that user's home directory and built there.

Kernel debug logs

KAIT2EN modules use pr_debug() for verbose driver messages. These messages are hidden by default, even when you watch dmesg or journalctl -k.

If you want to see the verbose logging, you can either search and replace all occurrencies of pr_debug in this repository with pr_info or use dynamic debug.

Fedora kernels support dynamic debug, so you can enable these messages at runtime. Mount debugfs if it is not already mounted:

sudo mount -t debugfs none /sys/kernel/debug

Enable all debug messages from the t2bce module:

echo 'module t2bce +p' | sudo tee /sys/kernel/debug/dynamic_debug/control

Watch the kernel log:

sudo dmesg -w

or:

journalctl -k -f

For audio-only debug messages, enable just the audio source file:

echo 'file audio/audio.c +p' | sudo tee /sys/kernel/debug/dynamic_debug/control

Turn the messages off again:

echo 'module t2bce -p' | sudo tee /sys/kernel/debug/dynamic_debug/control

Next: Revert T2 Linux Fedora to vanilla + KAIT2EN