How Ubuntu Ships Kernels: GA, HWE, Mainline, and DKMS

In 2022 I published this as a Mainline one-liner: add a PPA, mainline --install-latest, reboot. The commands still work. They were never the interesting part.

Ubuntu does not have one kernel you “upgrade.” It has a shipping model. GA stays on the version that shipped on day one. HWE rolls forward from interim releases. OEM is a vendor-laptop cadence that is supposed to fold back. Mainline is a set of unofficial builds from kernel.ubuntu.com that Canonical does not support. DKMS is the reason jumping tracks is not free on a laptop.

This post is that model, then the commands. If you only wanted the installer, skip to Mainline. If a laptop “needs a newer kernel,” start here instead.

The Mental Model

Four tracks, plus one thing that is not a track:

Track	Metapackage	What it is	Who should use it
GA	`linux-generic`	The kernel version frozen on LTS day one. Security backports for the full LTS life. No new drivers.	Servers, ABI-sensitive workloads, hardware that already works.
HWE	`linux-generic-hwe-YY.MM`	A newer upstream version, rolled about every six months until it matches the next LTS GA kernel. Canonical-supported.	Desktops and laptops on LTS. This is the default on Ubuntu Desktop since 20.04.
OEM	`linux-oem-*`	Early drivers for specific vendor machines. Meant to land in GA/HWE later, then the machine moves over.	Preinstalls and laptops `ubuntu-drivers list-oem` names.
Mainline	none (third-party debs)	Upstream builds, unsigned, no Ubuntu patches, no security maintenance.	Testing, or hardware that HWE/OEM still does not know.

Interim releases (25.10, and so on) are a different product: they already ship a current kernel and live about nine months. HWE exists because you stayed on LTS and still needed that newer kernel without leaving LTS.

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Same Ubuntu 24.04 userspace
        |
        +-- GA  6.8  ------------------------------> April 2029
        |
        +-- HWE 6.8 → 6.11 → 6.14 → 6.17 → 7.0
        |         .2     .3     .4     .5
        |
        +-- OEM  (vendor kernel, then fold into HWE/GA)
        |
        \-- Mainline  whatever Linus tagged last week
                      (not on this diagram's support clock)

The numbers above are the 24.04 story as Canonical published it. Look up the live table on Ubuntu kernel lifecycle before you quote a point-release kernel; HWE versions move. As of September 2026, 26.04 LTS GA is Linux 7.0. On a fresh 26.04 desktop, HWE and GA are still the same kernel until the first HWE roll.

GA and HWE are different kernel versions, packaged side by side. You cannot mash them into one tree. uname -r will say -generic for both. The version number and the metapackage tell you which track you are on, not the flavour suffix.

Desktop vs Server

This is the default people miss.

Ubuntu Desktop (20.04 and later, including Kubuntu) tracks HWE. A 24.04 laptop installed from current media is already on the enablement stack. linux-generic-hwe-24.04 is not an exotic opt-in; it is what the installer put there.
Ubuntu Server stays on GA unless you install the HWE metapackage. That is the conservative choice for ABI-sensitive services.

So “my LTS kernel looks old” on a desktop often means “I am on HWE, and the next roll has not shipped yet,” not “I forgot to upgrade.” On a server it may mean you are still on GA on purpose.

OEM is a third default on some vendor images. Check before you “fix” it:

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ubuntu-drivers list-oem

If that prints packages, the machine is on the OEM cadence, not plain HWE. Install what it names rather than guessing linux-generic-hwe-*.

Why a Laptop Needs a Newer Kernel

The kernel is the first driver tree the hardware meets. Userspace can be current and the machine still blind if the kernel does not know the chip.

Typical reasons a laptop wants a kernel newer than GA:

Wi-Fi / Bluetooth — Intel BE200-class, MediaTek, and new USB Bluetooth dongles land in mainline first. GA will not grow those drivers. HWE might, six months later.
GPU — Intel Arc, new NVIDIA laptop IDs, display-link and USB4 / Thunderbolt quirks. On a hybrid Intel + NVIDIA machine, who owns the HDMI port is a wiring fact (I wrote that up separately); whether the driver even binds is a kernel-and-module fact.
Audio — SOF firmware, new codecs, missing internal mic or speakers until a later kernel.
Power / suspend — s2idle vs deep, AMD/Intel idle bugs, the difference between “lid close works” and “lid close hangs.”
The calendar — you bought the laptop 18 months after LTS day one. GA is frozen at day one. HWE exists for that gap.

That is why kernels felt old on Ubuntu LTS unless you chased HWE, OEM, or mainline. Manjaro’s rolling kernel is a different shipping model, not a moral victory. Ubuntu’s model is: stay on one userspace, swap the kernel track.

HWE is usually enough. The laptop case for mainline is: HWE’s current roll still does not know this SKU, OEM did not publish a kernel for it, and you would rather run an unsupported kernel than wait.

DKMS: The Cost of Changing Tracks

In-tree drivers travel with the kernel. Out-of-tree modules do not. NVIDIA’s proprietary driver, VirtualBox, some Wi-Fi, v4l2loopback, ZFS — those are built against the running kernel’s ABI when the kernel is installed. DKMS (Dynamic Kernel Module Support) is that rebuild hook.

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apt installs linux-image-X
        |
        +--> linux-headers-X must exist
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        +--> DKMS rebuilds each registered module for X
        |
        +--> on Secure Boot, the new .ko must be signed
             (Ubuntu's nvidia packages hook this for Ubuntu kernels)

When it works, you reboot and nvidia-smi still answers. When it fails, you get a black screen, NVIDIA-SMI has failed, or a module that refuses to load, and GRUB still lists the new kernel first.

Ubuntu kernels (GA, HWE, OEM) ship matching linux-headers-* metapackages. DKMS is wired. NVIDIA from Ubuntu’s ubuntu-drivers / linux-modules-nvidia-* path is built for those ABIs. Secure Boot stays possible because Canonical signs the kernel.

Mainline kernels are a different ABI (6.17.0-061700-generic vs Ubuntu’s 6.17.0-xx-generic). Headers come from the same unofficial debs. DKMS may fail because:

the compiler the mainline kernel was built with is not in your release (gcc-15: not found on an older LTS is a real failure mode)
the NVIDIA Ubuntu package is not built for that ABI
the kernel image is unsigned, so Secure Boot refuses to boot it (bad shim signature) even if DKMS succeeded

Check the damage before you reboot into a new kernel as the default:

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uname -r
dkms status
dpkg -l "linux-headers-$(uname -r)" | grep ^ii
mokutil --sb-state

dkms status should show installed for each module on the kernel you are about to boot. Empty output means you have no DKMS modules — mainline is cheaper for you. installed on the old kernel and missing on the new one means you do not boot that kernel until the rebuild is fixed.

Which Track Are You On?

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uname -r
lsb_release -ds
dpkg -l 'linux-generic*' 'linux-image-generic*' 'linux-oem*' 2>/dev/null | grep ^ii
hwe-support-status --verbose

Read it like this:

Version 6.8.0-*-generic on 24.04, with linux-generic and no linux-generic-hwe-24.04 → GA.
A newer 6.x or 7.x on 24.04, with linux-generic-hwe-24.04 installed → HWE. Desktop installs look like this.
linux-oem-* installed, or ubuntu-drivers list-oem is non-empty → OEM.
Version like 7.1.0-070100-generic (three-digit extra in the middle) → someone installed mainline. That is not an Ubuntu metapackage.

hwe-support-status comes from update-manager-core. It tells you whether the HWE stack you are on is still in its support window. Each rolling HWE kernel is supported until the next one replaces it; the final HWE kernel (the next LTS GA, backported) rides until this LTS ends. That is why “HWE is shorter-lived” is true per roll and false for the last roll.

The Supported Path: Install HWE

On an LTS server (or a desktop that was pinned to GA):

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sudo apt update
sudo apt install --install-recommends linux-generic-hwe-$(lsb_release -sr)

Reboot. GRUB should pick the new kernel. GA stays installed as a fallback under Advanced options.

To go back to GA: boot the GA kernel from GRUB, then remove the HWE metapackage (linux-generic-hwe-24.04 or linux-generic-hwe-26.04) and sudo apt autoremove. Do not delete images by hand while they are still the running kernel.

On Desktop, this command is often a no-op — you are already tracking HWE. If uname -r is still the GA version months after a point release that shipped a newer HWE, then install the metapackage and check you did not pin linux-generic in /etc/apt/preferences.d/.

Live versions and EOL dates: Ubuntu kernel lifecycle. Variant names: Ubuntu kernel variants.

Mainline: The Last Rung

This is the 2022 recipe, in its proper place.

The builds live at kernel.ubuntu.com/mainline. They are not Ubuntu kernels. They do not get Canonical security updates. They are unsigned. The Mainline installer (PPA ppa:cappelikan/ppa) is a third-party UI over those debs — the same family of tool as the old ukuu.

Use it when HWE and OEM still do not know the hardware, you accept DKMS and Secure Boot cost, and you can still boot an Ubuntu kernel from GRUB if it goes wrong.

Install the installer:

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sudo add-apt-repository ppa:cappelikan/ppa
sudo apt update
sudo apt install mainline

Install a kernel:

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sudo mainline --list
sudo mainline --install-latest
# or: sudo mainline --install <name>

Reboot. Confirm uname -r and dkms status. When a newer mainline kernel is running and you do not need the older mainline packages:

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sudo mainline --uninstall-old

--include-unstable adds RC builds. Do not do that on a machine you need tomorrow.

The Ubuntu mainline PPA has gone missing before. The installer cannot invent builds that kernel.ubuntu.com is not publishing.

Common Mistakes

Jumping to mainline because uname looks old. On Desktop you are probably already on HWE. Compare with the lifecycle table for this LTS, not with Fedora or Manjaro.
Treating HWE as unsupported. It is Canonical-supported. Each roll has a shorter window; the last roll lasts until LTS EOL.
Installing HWE on OEM. If ubuntu-drivers list-oem lists packages, that is the track. Mixing OEM and HWE is how you get two “almost right” kernels and a surprise GRUB default.
Mainline with Secure Boot still on. The kernel never boots. You debug the wrong layer.
Mainline without headers / DKMS. NVIDIA goes black. Check dkms status on the new kernel version before you make it the default.
Removing the GA/HWE metapackage while it is the only bootable signed kernel. Always keep one Ubuntu kernel you can select in GRUB.
Using mainline on a server. There is no laptop-SKU excuse. Stay on GA or HWE.

What This Post Does Not Cover

Building your own kernel. Ubuntu Pro / ESM calendars beyond “GA is the long clock.” Cloud variants (linux-aws, linux-azure, linux-gcp) — same idea (a kernel variant), different SKU. Compiling NVIDIA from the .run installer. Changing series (24.04 → 26.04) is a release upgrade, not a kernel track. Those are adjacent shelves.

The Mental Model#

Desktop vs Server#

Why a Laptop Needs a Newer Kernel#

DKMS: The Cost of Changing Tracks#

Which Track Are You On?#

The Supported Path: Install HWE#

Mainline: The Last Rung#

Common Mistakes#

What This Post Does Not Cover#

Further Reading#

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