A (nearly) mainline kernel running on the Nexus 7

[Posted March 15, 2016 by corbet]

As was discussed at the 2015 Kernel Summit, there are essentially no commercial Android devices running mainline kernels. At the recently concluded Linaro Connect event, though, John Stultz demonstrated a Nexus 7 tablet running mainline with just a few patches. It even has accelerated graphics via the freedreno driver. "This is really great, because we now have a very-close to mainline test bed on a actual consumer device. So we can make sure upstream doesn't introduce any regressions (just recently, two ABI breaks that affected android were recently caught) and allows us to make sure when we push Android functionality upstream, that any interface changes required by maintainers can be properly tested to make sure what lands upstream really works."

A (nearly) mainline kernel running on the Nexus 7

Posted Mar 15, 2016 15:08 UTC (Tue) by pboddie (guest, #50784) [Link] (6 responses)

My impression is that the OpenMoko descendants GTA04 and Neo900, plus the Pyra, all aim for mainline kernel support. Of course, all of those are OMAP devices, which might not satisfy those who want the very latest "commercial" (and inevitably proprietary) hardware, and they are all in different stages of development. (GTA04 has already had a few revisions, Pyra will be ready next, Neo900 is somewhat stalled.)

I also got something of an impression that Fairphone version 2 might be more able to track the mainline kernel, too, after they chose a more supportable chipset, but I haven't really looked into that very much.

A (nearly) mainline kernel running on the Nexus 7

Posted Mar 15, 2016 16:11 UTC (Tue) by robclark (subscriber, #74945) [Link] (4 responses)

> My impression is that the OpenMoko descendants GTA04 and Neo900, plus the Pyra, all aim for mainline kernel support. Of course, all of those are OMAP devices, which might not satisfy those who want the very latest "commercial" (and inevitably proprietary) hardware, and they are all in different stages of development. (GTA04 has already had a few revisions, Pyra will be ready next, Neo900 is somewhat stalled.)

OMAP does have pretty good upstream kernel support, although sadly not much of a future, and isn't showing up in any mass produced devices. It does have the advantage of being a simpler architecture compared to snapdragon... I *think* snapdragon is the most complex/sophisticated SoC out there in terms of all the PM tricks it has up it's sleeves, which actually makes the progress on upstream snapdragon support all the more impressive.

> I also got something of an impression that Fairphone version 2 might be more able to track the mainline kernel, too, after they chose a more supportable chipset, but I haven't really looked into that very much.

From a quick look, looks like fairphone is snapdragon 800 (8x74)? That is a bit more complex beast than the apq8064 if nexus7 (and nexus4), although patches on top of linux-next do exist for getting the gpu and display working (for example, xperia z3).

A (nearly) mainline kernel running on the Nexus 7

Posted Mar 15, 2016 16:37 UTC (Tue) by sre (subscriber, #81338) [Link]

>> My impression is that the OpenMoko descendants GTA04 and Neo900, plus the Pyra, all aim or mainline kernel support. Of course, all of those are OMAP devices, which might not satisfy those who want the very latest "commercial" (and inevitably proprietary) hardware, and they are all in different stages of development. (GTA04 has already had a few revisions, Pyra will be ready next, Neo900 is somewhat stalled.)
> OMAP does have pretty good upstream kernel support, although sadly not much of a future, and isn't showing up in any mass produced devices. It does have the advantage of being a simpler architecture compared to snapdragon... I *think* snapdragon is the most complex/sophisticated SoC out there in terms of all the PM tricks it has up it's sleeves, which actually makes the progress on upstream snapdragon support all the more impressive.

FWIW you can run mainline on (OMAP3-based) N900 since quite some time. It basically lacks support for 3 things: Cameras, Bluetooth, GPU.

Details: http://elinux.org/N900

A (nearly) mainline kernel running on the Nexus 7

Posted Mar 16, 2016 5:19 UTC (Wed) by voltagex (guest, #86296) [Link] (2 responses)

Wait, the Nexus 7 2013 uses the same chipset as the Nexus 4? The 4 has serial-out via headphone jack so I may just be able to have a go at running this kernel on it!

A (nearly) mainline kernel running on the Nexus 7

Posted Mar 16, 2016 11:54 UTC (Wed) by robclark (subscriber, #74945) [Link] (1 responses)

> Wait, the Nexus 7 2013 uses the same chipset as the Nexus 4? The 4 has serial-out via headphone jack so I may just be able to have a go at running this kernel on it!

yes, I think the n4 may be an earlier revision of apq8064, but similar. I expect it is mainly a matter of putting together devicetree bits for n4. It may be wired up similarly enough to n7 to use the n7 dts as a starting point, not sure. Probably you would need to compare board files for the two in the downstream 3.4 kernel.

both should have headphone jack uart, so the good news is no soldering required ;-)

A (nearly) mainline kernel running on the Nexus 7

Posted Mar 18, 2016 0:54 UTC (Fri) by voltagex (guest, #86296) [Link]

I'm definitely going to need some help with this, but it's seeming like it's more acheivable for me than it was a year ago.

A (nearly) mainline kernel running on the Nexus 7

Posted Mar 16, 2016 5:44 UTC (Wed) by rsidd (subscriber, #2582) [Link]

I think the point is to have a mainline kernel running on an android system. Given the extensive divergence that occurred in the early days, convergence back to the mainline is not only desirable but is a very impressive feat.

A (nearly) mainline kernel running on the Nexus 7

Posted Mar 15, 2016 19:32 UTC (Tue) by djs_tx (guest, #29646) [Link] (2 responses)

Wouldn't this make it more likely to get functional 3rd party user experiences on commercial devices (at least in theory)? I would think that Ubuntu touch porting efforts would be a lot easier with a mainline kernel. Enlighten my noobness here...

A (nearly) mainline kernel running on the Nexus 7

Posted Mar 16, 2016 1:12 UTC (Wed) by pabs (subscriber, #43278) [Link] (1 responses)

You could essentially run anything that is in any Linux distro, from Budgie to awesome.

A (nearly) mainline kernel running on the Nexus 7

Posted Mar 16, 2016 1:13 UTC (Wed) by pabs (subscriber, #43278) [Link]

Caveat: things that need OpenGL/GPU support will only work on some devices as mesa doesn't support Mali, PowerVR and others. That said, there are blobs that may or may not work, may need libhybris and may or may not be redistributable.

Very impressive!

Posted Mar 17, 2016 17:39 UTC (Thu) by david.a.wheeler (subscriber, #72896) [Link]

I'd love to see convergence back to the point where the same source can be compiled and run everywhere (ideally). I think that would help with security - there'd be more eyes on the code (because it's in *everyone's* tree), and if there's a vulnerability, you can take the *standard* kernel, recompile, and deploy (if jailbroken). Yes, I realize there are roadblocks and limitations, but it's not insane.