XanMod 6.18.8 brings LLVM ThinLTO, BBRv3 and an optional PREEMPT_RT build to Debian‑based machines, delivering noticeably smoother I/O and scheduler performance on everyday hardware. This step‑by‑step guide shows how to add the repository, import the signing key, install the kernel and pull in just the DKMS toolchain you actually need. It also warns about the most common module breakages – NVIDIA, VirtualBox and older NVIDIA drivers – and gives quick fixes that saved me from a black screen. Keep a fallback kernel handy, reboot, and verify with uname -r to make sure you’re running the new 6.18.8‑xanmod1 kernel.
XanMod Kernel 6.18.8 and 6.12.68 LTS released – what you need to know
Both XanMod 6.18.8 and its LTS counterpart 6.12.68 were published today, so if you’ve been waiting for the newest scheduler tweaks or a stable long‑term build, this is the exact recipe you’re after. You’ll get the repo setup, the minimal DKMS toolchain you actually need, and the common stumbling blocks that have left my machine in limbo before.
Why bother with XanMod?
The 6.18 branch adds LLVM ThinLTO, aggressive x86_64 micro‑optimisations, Google’s BBRv3 congestion control and a built‑in PREEMPT_RT variant for low‑latency workloads. In practice I’ve seen about a 10 % lift in synthetic I/O benchmarks on an old i7‑9700 when the block layer runqueue is enabled. If you’re doing heavy compiles, gaming, or running VMs, those tweaks can shave seconds off load times.
But it’s not free lunch: some DKMS modules (VirtualBox, VMware, older NVIDIA drivers) refuse to compile against the new symbols.
Prepare a safety net
Before you touch the bootloader, install a known‑good kernel (e.g., linux-image-amd64 from your distro) and keep it in GRUB’s menu. If the new XanMod entry refuses to boot, select the older one and you’re back in business.
sudo apt install linux-image-amd64 # Debian/Ubuntu generic fallback
Why? Keeping a fallback kernel prevents you from getting stuck with an unbootable system.
Register XanMod’s signing key
The repo is signed with a PGP key; without it apt will refuse to trust the packages. The command below downloads the key, converts it to the modern “keyring” format and drops it where APT expects it.
wget -qO - https://dl.xanmod.org/archive.key | sudo gpg --dearmor -vo /etc/apt/keyrings/xanmod-archive-keyring.gpg
Why? Storing the key in /etc/apt/keyrings isolates it from the global trusted‑key pool, which is a nice security hygiene.
Add the repository for your distro codename
Replace $(lsb_release -sc) with whatever Ubuntu or Debian version you run (bookworm, jammy, noble, etc.). The line writes a new source file under /etc/apt/sources.list.d.
echo "deb [signed-by=/etc/apt/keyrings/xanmod-archive-keyring.gpg] http://deb.xanmod.org $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/xanmod-release.list
Why? The signed‑by clause tells APT to verify packages with the key we just installed, preventing a rogue repo from sneaking in.
Update and install the kernel
XanMod ships several flavours; the “x64v3” build is the one most users need (it targets the modern x86‑64 psABI level). If you want the RT variant, replace linux-xanmod-x64v3 with linux-xanmod-rt.
sudo apt update && sudo apt install linux-xanmod-x64v3
During installation APT will automatically add a new entry to /boot/grub/grub.cfg. No manual grub edits required.
Pull in the minimal DKMS toolchain (optional but recommended)
If you rely on out‑of‑tree drivers – VirtualBox, NVIDIA, or custom Wi‑Fi modules – you’ll need dkms plus a recent compiler stack. The “no‑install‑recommends” flag keeps the install lean; you only get what you ask for.
sudo apt install --no-install-recommends dkms libdw-dev clang lld llvm
Why? DKMS recompiles modules against the new kernel headers automatically on boot. Skipping these packages will leave you with “module not found” errors.
Reboot and verify
A quick reboot lands you on the XanMod kernel. Verify with uname -r; you should see something like 6.18.8-xanmod1.
uname -r
If everything boots, run a sanity check – for example, dmesg | grep BBR to confirm the TCP congestion algorithm is active.
Common pitfalls and how to fixed them
| Symptom | What happened | Fix |
|---|---|---|
| VirtualBox won’t start (vboxdrv not loaded) | DKMS build failed because kernel headers weren’t installed before the XanMod package. | Install linux-headers-$(uname -r) before rebooting, then run sudo dkms autoinstall. |
| NVIDIA driver shows “Failed to load kernel module” after upgrade | Driver was compiled against 6.12.x; new symbols in 6.18 broke it. | Purge the old driver (sudo apt purge nvidia-driver-*), reinstall from the official repo, then reboot. |
| System hangs on boot, only a black screen | You upgraded on a laptop with an older BIOS that didn’t like the new acpi_rev_override. | Boot into the fallback kernel, edit /etc/default/grub to add acpi_rev_override=0, run sudo update-grub, and try again. |
Rolling back if you need to
Should XanMod prove too unstable for your workload, simply boot the previous entry in GRUB, then purge the package:
sudo apt remove linux-xanmod-x64v3
sudo update-grub # cleans up stale entries
Your system will fall back to the generic kernel you installed earlier.
Give it a spin; the scheduler tweaks are subtle but noticeable on busy desktops. If anything goes sideways, you’ve already got a safety net – that’s the whole point of keeping a known‑good kernel in GRUB.
