[strcat]

Linux 6.12 is not better for security than Linux 6.1 or Linux 6.6. It doesn't work that way. Newer kernels have substantially more attack surface and complexity. They also have tons of new bugs. Bug density is far higher in new or recently changed code. Bug density drops over time. However, backporting patches gets increasingly less complete for the older branches. There's a balance between the new and older branches. 6.12 is far too new to be a reasonable choice. Google already ported Pixels to Linux 6.12, etc. It's not what is shipped because it's full of serious bugs. Separately from that, if you believe using an LTS release and shipping the latest revisions means you avoid regularly having serious regressions, that's very wrong with the Linux kernel.

Pixels only recently started moving to new LTS releases and will likely be moving to a new LTS release each year going forward. Moving the older generations to 6.1 to match current devices was done in March 2025. They'll likely move along together to a new branch each year going forward.

Linux kernel LTS revisions are nothing like LTS revisions of most other projects. They're largely untested patches blindly applied by the LTS maintainers based on patches to mainline being marked for stable backports. If the patches apply cleanly, they ship. If they don't apply cleanly, they largely don't ship. Whether it works is an open question.

> GrapheneOS is currently shipping a kernel for the Pixel 6 that's 3 minor versions behind

That's not quite right.

We're shipping the latest Linux 6.1 and Linux 6.6 GKI LTS branch releases from Greg KH. They're currently in between 2 upstream revisions upstream, not on a specific one. The devices all use both 6.1 and 6.6, not just 6.1. They use 6.1 for bare metal and 6.6 for virtual machines. Even the Pixel 6 has been ported to 6.13 by Google but that doesn't mean that's a stable enough kernel ready to ship.

The Android kernel branches also have a bunch of backports not included in the kernel.org LTS releases, including security patches and improvements they decided were important. Google does their own backporting and fixes in the GKI branch and Greg KH merges those into the GKI LTS branch. The kernel branch we use is the combination of the Google GKI backporting/fixes with the kernel.org backporting. The kernel.org LTS releases are far messier than you realize, and combining these things is messy too.

Linux LTS kernels are not very well tested and have tons of regressions. Quickly updating to the new LTS versions is problematic and we regularly encounter major regressions, especially in certain areas like f2fs and USB. We still update right away to the new GKI LTS versions. We're currently on the latest GKI LTS releases for each branch.

You'd have to ask Greg KH why there are still delays despite Google supporting it. It still seems to be him doing most of the kernel.org LTS and also GKI LTS work by himself, without nearly as much review or help by others as you would think. This is also tied into the severe regressions regularly happening with the LTS releases. Those can be security regressions too. Immediately updating to them is not necessarily a great idea with how much goes wrong at the moment.

They unfortunately sometimes lag behind the kernel.org releases. We used to merge the latest upstream kernel.org LTS releases ourselves but Greg KH convinced us we don't need to do that anymore and should just use the GKI LTS branch instead. We're not completely happy with it since it's not fully kept in sync but we're using our resources elsewhere at the moment.

> Actually, the much better comparison is that Debian 12 is shipping 6.1.133 according to https://packages.debian.org/stable/kernel/linux-image-arm64 now. So the super stable slow moving distro is in fact still ahead of Android, even slightly lagging as it is.

Debian is usually further behind than Greg KH's GKI LTS branch. Comparing at a snapshot in time doesn't mean much. GKI LTS branch should really be kept in sync but the GKI ABI stability system makes maintenance hard and is entirely worthless for Pixels. We would prefer if the whole GKI system did not exist. For Pixels, the kernel image and all the drivers are built with the same kernel source tree for Pixels so the whole system for driver ABI compatibility is just making things more complex and worse.

> As to breakage/testing... Yes, someone has to test new versions. Ideally that'd be a CI farm flashing and testing devices, but I appreciate that it's not exactly a trivial problem. Nonetheless, if that results in Graphene not shipping the latest bugfixes, I feel like that's an extremely awkward position to be in.

We do heavily test them. Our community helps with it. We OFTEN find regressions in the new LTS kernels. It often takes months before the issues we find and work around get fixed upstream. It's worth noting that due to mistreatment we've largely stopped helping them except for firmware, hardware or things we don't want to maintain downstream for some reason. It would be better if everyone collaborated on maintaining LTS kernels but instead it's largely 1 person and a couple others doing it with support from Google for testing, etc.

[yjftsjthsd-h]

Right, no, I wasn't particularly objecting to 6.1, I was pointing at the patch level on it. I would personally take [quickly checks kernel.org] 5.15.180 (latest 5.15) over 6.1.130 (not-latest 6.1), because I'm more concerned with bugfixes than feature releases at this point. If the GKI LTSs are backporting fixes, that may well cover it, although that starts to veer into making me nervous because I rather agree with

> Linux kernel LTS revisions are nothing like LTS revisions of most other projects. They're largely untested patches blindly applied by the LTS maintainers based on patches to mainline being marked for stable backports. If the patches apply cleanly, they ship. If they don't apply cleanly, they largely don't ship. Whether it works is an open question.

I'm also not super fond of frankenkernels. And... I'm confused how you feel about them? If backports suck, shouldn't you want to be chasing the very bleeding edge? I wasn't originally intending to argue that everything had to ride the very latest and greatest, but if backporting is inherently fragile and bug-prone, shouldn't you want to be on the very latest stable version (so as of this writing, 6.14.2)?

[strcat]

We want to be on an LTS branch, but we'd prefer to be on a newer LTS branch. We would currently want to be on 6.6 with a near future move to 6.12 once it was stabilized enough. However, we would much rather be on what Google is heavily testing than using a kernel they're not using on their CI infrastructure and production devices.

Pixels moving 6th, 7th and 8th gen devices to 6.1 happened in March 2025. It's the first time they've moved to new LTS branches. It's likely going to move to using a newer LTS release where it would currently be using 6.6 and then moving to 6.12 after the next one comes out. We expect they move to having around a year to stabilize the new LTS and then use it for around a year before moving to the next. That fits nicely into the new 2 year lifespan for LTS kernels. This is a transition period. Once the longer than 2 year LTS kernels are gone, the quality of the LTS kernels will rise because there won't be as many to maintain. There are currently too many combined with too few people working on it. Greg KH having to handle both the kernel.org LTS and GKI LTS doing a huge portion of the work is clearly a problem. We'd also like to see the end of GKI ABI stability but that's highly unlikely. Yearly moves to new LTS kernels will at least make it a lot better.

> I would personally take [quickly checks kernel.org] 5.15.180 (latest 5.15) over 6.1.130 (not-latest 6.1)

Latest 5.15 has far fewer fixes backported for the same time periods than 6.1. The missing fixes in 5.15 are far more than a couple minor revisions. Similarly, 6.6 has more than 6.1 for the same time period and 6.12 has more than 6.6.

> And... I'm confused how you feel about them? If backports suck, shouldn't you want to be chasing the very bleeding edge? I wasn't originally intending to argue that everything had to ride the very latest and greatest, but if backporting is inherently fragile and bug-prone, shouldn't you want to be on the very latest stable version (so as of this writing, 6.14.2)?

Linux kernel code quality, review and testing is quite low. The bleeding edge kernels are nearly unusable in production for this use case (users running all kinds of software, using all kinds of different Bluetooth, USB, etc. accessories and so on while caring deeply about battery life) and have a ton of newly added security bugs which aren't found and fixed yet. We think that's a much bigger issue. We happily use Arch Linux for a lot of stuff but we use the LTS kernel package which is 6.12 at the moment.

If LTS quality was increased substantially, then we'd want to be on the latest LTS branch a while after the initial release, i.e. 6.12.15+ or so. However, at the moment, some serious regressions take them so long to find that it's still too new. We have high stability requirements where we can't have niche USB functionality, Bluetooth, video recording, etc. functionality regressing. The out-of-tree drivers are an area we don't have as much pain with since they're nearly all made for Exynos / Pixels and the drivers from the vendors so changes actually get tested well. The regressions are in the upstream code. More stuff coming from upstream would make LTS updates more, not less, painful, other than the GKI ABI stability nonsense we don't want.

[mixmastamyk]

Ton of information here. But was hoping to find out how mobile Linux distros (mobian, postmarket, pureos, new ones) could support newer phones, like these Pixels. I still don't know after reading this thread. :-D

I don't want to use Android, I want to use Linux and Phosh or similar. But so far, the supported hardware is junk.

[strcat]

GrapheneOS is a mobile Linux distribution. It's not systemd and GNOME which makes it a Linux distribution but rather the Linux kernel. There's nothing stopping people from running a traditional desktop Linux software stack on the same hardware we support. That doesn't interest us since it would be a massive privacy and security regression from the Android Open Source Project. It would also give a lot of usability, robustness and the huge mobile app ecosystem including a large number of open source mobile apps.

The Linux kernel is increasingly the elephant in the room when it comes to security and hasn't experienced anything like the massive progress made in Android's security in userspace. Piling on many more exploit mitigations to the Linux kernel won't really change this. We need to do a lot more work on it than we already do.

GrapheneOS has hardware virtualization support, which is going to be one of the ways to avoid depending so much on the Linux kernel's fragile security. The main usage for it in GrapheneOS will be running nested GrapheneOS instances for better sandboxing rather than running other operating systems. Android supports using the virtualization support to run other operating systems via the Terminal app and we have support for GUI applications, speaker, microphone and opt-in GPU acceleration backported to the Terminal app. The main use case for that app will be running desktop applications from other operating systems for the desktop mode. Windows 11 support would be a compelling addition to it and we may implement that in the next year or so.

[mixmastamyk]

I'd like a mobile OS where I can reuse my existing knowledge. Write software for it with Rust, Python, pipewire, systemd, Wayland, etc. Login with ssh.

No interest in Android apps or Windows (hah). (Though maybe I'll try Waydroid one of these days.)

I don't know anything about your distro, not the graphics stack or what the package manager is or even if there is one? Meanwhile my starlite tablet is awesome because it works just like my desktop Fedora or Mint, though I installed Phosh on it.

Security is nice, but not before there is even a single feasible device on the market. Librem is just barely limping along, and I mean barely with a five year old handset that was obsolete when it debuted.

If your kernel is so advanced it really should be upstreamed, so these other distros could use it and support new Pixels. Y'all working together with other mobile projects would be so much better than the current surveillance dystopia we are currently living in. Maybe it's hard, but it is incredibly important. I can help though have limits.

[yjftsjthsd-h]

GrapheneOS is an Android/Linux distro, not GNU/Linux or musl+busybox/Linux; I suspect most of their security work isn't portable to the unixy Linux distros.