linux-zen-x1c

Custom Linux kernel optimized for ThinkPad X1 Carbon Gen 11 using localmodconfig.

System Requirements

This kernel is designed for a specific boot configuration:

Component	Configuration
Bootloader	systemd-boot
Encryption	LUKS2 (dm-crypt)
Root filesystem	Btrfs with subvolumes
Initramfs	mkinitcpio with sd-encrypt hook

The boot process uses systemd-boot with LUKS encryption via the sd-encrypt mkinitcpio hook, allowing automatic unlock with a keyfile stored on the EFI partition.

Overview

Property	Value
Base	linux-zen 6.18.2.zen2
Target	ThinkPad X1 Carbon Gen 11
CPU	Intel Core i7-1370P (Raptor Lake-P)
Build Method	localmodconfig + menuconfig
Last Updated	2025-12-29

Benefits

Metric	Stock	Custom	Improvement
Initramfs	29 MB	23 MB	-21%
Boot time	55s	48s	-12%
Context switches	31.6ms	16.3ms	-48%
File I/O	7,272 MiB/s	21,422 MiB/s	+195%
Memory bandwidth	5,263 MiB/s	8,001 MiB/s	+52%
CPU performance	~40,000 ev/s	~40,000 ev/s	Identical

Hardware Support

Enabled

CPU & Power

• Intel Raptor Lake (native optimizations)
• Intel P-State + RAPL
• Low-latency preemption (PREEMPT)
• Full dynticks (NO_HZ_FULL)
• BORE scheduler

Graphics

• Intel Xe (DRM_XE)
• Intel i915 (DRM_I915)

Audio

• Intel SOF (sof-hda-dsp)
• USB Audio (eMeet Luna, dock audio)

Networking

• Intel WiFi (iwlmvm)
• Intel Bluetooth
• USB-C Dock Ethernet (cdc_ether)

Input

• Logitech Bluetooth (hid_logitech_hidpp)
• Logitech USB receiver (hid_logitech_dj)
• Bluetooth HID (hidp, uhid)

Storage

• NVMe
• Btrfs, ext4
• dm-crypt (LUKS)
• USB storage (uas)

Other

• ThinkPad ACPI
• KVM Intel virtualization
• Intel HW RNG

Disabled

• AMD CPU/GPU/KVM
• Nvidia graphics
• Intel AVS audio (conflicts with SOF)
• Other wireless drivers
• Legacy hardware (FireWire, PCMCIA, etc.)
• Server/datacenter features

Files

File	Purpose
PKGBUILD	Package build script with localmodconfig
config	Kernel configuration
benchmark.sh	Performance benchmark script
benchmark-results/	Benchmark comparison documentation
benchmarks/	Raw benchmark results
linux-zen-x1c.conf	systemd-boot entry template

Installation

Prerequisites

# Install build dependencies
sudo pacman -S base-devel bc cpio gettext libelf pahole perl python tar xz zstd

Download External Sources

The build requires external sources that are not tracked in git:

Source	URL
Linux kernel	https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.18.2.tar.xz
Kernel signature	https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.18.2.tar.sign
Zen patch	https://github.com/zen-kernel/zen-kernel/releases/download/v6.18.2-zen2/linux-v6.18.2-zen2.patch.zst
Zen patch signature	https://github.com/zen-kernel/zen-kernel/releases/download/v6.18.2-zen2/linux-v6.18.2-zen2.patch.zst.sig

Download automatically with makepkg:

cd ~/Workspace/linux-zen-x1c

# Download sources only (no build)
makepkg -o

# Or download and extract
makepkg -od

Or download manually:

cd ~/Workspace/linux-zen-x1c

# Kernel source
curl -LO https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.18.2.tar.xz
curl -LO https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.18.2.tar.sign

# Zen patches
curl -LO https://github.com/zen-kernel/zen-kernel/releases/download/v6.18.2-zen2/linux-v6.18.2-zen2.patch.zst
curl -LO https://github.com/zen-kernel/zen-kernel/releases/download/v6.18.2-zen2/linux-v6.18.2-zen2.patch.zst.sig

Build

cd ~/Workspace/linux-zen-x1c

# Capture currently loaded modules (boot stock kernel first if adding hardware)
lsmod > /tmp/modules.lst

# Build (downloads sources if not present)
MAKEFLAGS="-j$(nproc)" makepkg -s

# Install
sudo pacman -U linux-zen-x1c-*.pkg.tar.zst linux-zen-x1c-headers-*.pkg.tar.zst

Boot Entry (systemd-boot + LUKS)

Create /boot/loader/entries/linux-zen-x1c.conf:

title Arch Linux (Zen X1C)
linux /vmlinuz-linux-zen-x1c
initrd /intel-ucode.img
initrd /initramfs-linux-zen-x1c.img
options rd.luks.name=<LUKS-UUID>=cryptroot root=/dev/mapper/cryptroot rd.luks.key=<LUKS-UUID>=/luks-keyfile.bin:UUID=<EFI-UUID> rd.luks.options=<LUKS-UUID>=keyfile-timeout=5s rootflags=subvol=@arch rw

Parameters:

Parameter	Description
rd.luks.name=<UUID>=cryptroot	LUKS partition UUID and mapper name
rd.luks.key=<UUID>=/path:UUID=<EFI>	Keyfile path on EFI partition
rd.luks.options=<UUID>=keyfile-timeout=5s	Fallback to password after 5s
rootflags=subvol=@arch	Btrfs subvolume for root

Get your UUIDs:

# LUKS partition UUID
sudo blkid -s UUID -o value /dev/nvme0n1p2

# EFI partition UUID
sudo blkid -s UUID -o value /dev/nvme0n1p1

Usage

Boot into custom kernel

Select "Arch Linux (Zen X1C)" from systemd-boot menu.

Verify

uname -r  # 6.18.2-zen2-1-zen-x1c

Set as default

sudo bootctl set-default linux-zen-x1c.conf

Updating

When upstream linux-zen updates

cd ~/Workspace/linux-zen-x1c

# Get new PKGBUILD from AUR or upstream
# Edit: change pkgbase to linux-zen-x1c
# Edit: add localmodconfig section in prepare()

# Capture modules
lsmod > /tmp/modules.lst

# Build and install
MAKEFLAGS="-j$(nproc)" makepkg -s
sudo pacman -U linux-zen-x1c-*.pkg.tar.zst linux-zen-x1c-headers-*.pkg.tar.zst

Quick rebuild (config changes only)

cd ~/Workspace/linux-zen-x1c
MAKEFLAGS="-j$(nproc)" makepkg -ef
sudo pacman -U linux-zen-x1c-*.pkg.tar.zst linux-zen-x1c-headers-*.pkg.tar.zst

Adding Hardware

If new hardware doesn't work:

1. Boot stock kernel (linux-zen)
2. Connect hardware
3. Find module: lsmod | grep <name>
4. Add config:

   cd ~/Workspace/linux-zen-x1c/src/linux-*/
   scripts/config --module CONFIG_<NAME>
   make olddefconfig

5. Rebuild kernel

Supported Hardware

Hardware	Module	Config
Dock Ethernet	cdc_ether, usbnet	CONFIG_USB_USBNET, CONFIG_USB_NET_CDCETHER
Logitech Bluetooth	hid_logitech_hidpp, hidp	CONFIG_HID_LOGITECH_HIDPP, CONFIG_BT_HIDP
Logitech USB receiver	hid_logitech_dj	CONFIG_HID_LOGITECH_DJ
USB Audio	snd_usb_audio	CONFIG_SND_USB_AUDIO
Bluetooth HID	hidp, uhid	CONFIG_BT_HIDP, CONFIG_UHID
USB Storage	usb_storage, uas	CONFIG_USB_STORAGE, CONFIG_USB_UAS

Benchmarking

# Set performance mode
echo performance | sudo tee /sys/firmware/acpi/platform_profile

# Cooldown
sleep 60

# Run benchmark
~/Workspace/linux-zen-x1c/benchmark.sh

# Results saved to:
# ~/Workspace/linux-zen-x1c/benchmarks/results-$(uname -r).txt

See benchmark-results/comparison.md for detailed analysis.

Troubleshooting

No audio

Ensure Intel AVS is disabled and SOF is enabled:

scripts/config --disable CONFIG_SND_SOC_INTEL_AVS
scripts/config --module CONFIG_SND_SOC_SOF_ALDERLAKE

Sudo password loop (fingerprint)

Enable Intel HW RNG:

scripts/config --module CONFIG_HW_RANDOM_INTEL

Bluetooth devices not working

Enable Bluetooth HID:

scripts/config --module CONFIG_BT_HIDP
scripts/config --module CONFIG_UHID

Rollback

Boot "Arch Linux (Zen)" from boot menu, or:

sudo pacman -R linux-zen-x1c linux-zen-x1c-headers

License

Kernel sources are GPL-2.0. Build scripts and documentation are MIT.