Custom Kernel for Lemfo LEM12 and Kospet PRIME

What this is about:

  • This is a reversed or re-created kernel source for the MT6739 Smartwatches, this is mostly done to help supporting possible upcoming open source Android versions.

Why this is needed:

  • Many chinese vendors (especially if they are associated with Mediatek) are extremely unlikely to release any kind of source due to … reasons.

How this was done:

  • Fortunately, Mediatek has a highly generic approach in implementing their code in the kernel source, which means that most MT6739 related functions are supported and working just by selecting a matching Mediatek source.
  • The problem here lies in the customized features that are implemented by the OEM and those are either reversed or ported from another public kernel source.

What is asked for:

  • Due to the nature of reversing there could be missing features or other problems that can only be tracked down by testing.
  • I appreciate any feedback to what is different, identical or missing in comparison to the stock kernel.




Maybe it’s a silly question, but I have to ask… What is the potential of a custom rom? Forbidden functionalities like bluetooth calling? :thinking:

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Prime SE also ? @none

Primarily a more recent Android version with all included fixes and security updates.

It looks identical to the Prime except for ram/storage, you might try it.
But be sure to create a backup / get a copy of the prime se firmware.


OK sir, this looks promising :grin:

Great work! Will this work without overwriting the user area? If so I will start trying this immediately.

Yes, this will only flash the kernel (boot.img file).
If you like to restore back to the default kernel, you just need to overwrite the boot.img from the firmware archive and flash it again.

You find the firmware here for the Lemfo LEM12 and for the Kospet PRIME.

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@none Thanks for your work and thanks for posting this in the right place :handshake::handshake::+1:

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So far so good, no problems or differences that I’ve noticed. Is there something in particular we should try to stress test?

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I’m actually wondering what benefits you will be getting from this kernel?
@none is there something in particular that people will notice if they flash this kernel?

I’m curious because we have had them before and tweaked governors and other things but no benefit was ever realised…

Great stuff by the way and I’m very grateful, but what do you think?
Better battery life or something else?

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Thanks, most important is that everything is working correctly (accelerometer, cameras, heart rate, sim, gps, charging/discharging, battery life).

As mentioned in the first post:

  • Due to the nature of reversing there could be missing features or other problems that can only be tracked down by testing.

This is mostly intended as ‘reference’ source that can refered to when migrating to a higher kernel version.


Ah ok,
I certainly didn’t want to give the wrong impression because I am very grateful that you have taken an interest.
Not only in working on these sources with the Openwatch team - but also posting your work here as well.
We have worked with the Openwatch guys for quite a while now.
Iscle is a moderator here as well, for example.
When he has the time :grin:
Anyway, welcome aboard :+1::+1:


Thanks, i was looking for a small android / embedded device to tinker with and those full android smartwatches were ideal.

Yes, Iscle and Deadman did a lot of awesome work for the OpenWatchProject, make it possible in the first place and can be credited as well.

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While listening to and navigating the YouTube Music app my Prime crashed. I had to hold the power button for about 30 seconds to boot. I got it to happen 2 more times so it’s a repeatable bug. After reverting to the original kernel this problem hasn’t happened again.

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Can you provide me a log when this happens?
Here is small archive that includes adb.exe and a script ‘Logfile.cmd’ that will pull the last kernel log from the device (usb-debugging needs to be enabled).

Here you go

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Thanks for the log, i made a new build that hopefully fix the music crash issue: PRIME #2
I also made some slight changes to the heart rate sensor, please check if it’s working correctly, thanks.

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The HRM is not working - the testing app says “test failed”. I’m pretty sure it was working with your first kernel. I also had a crash. Same situation but it took longer to crash than before. Here’s the log.

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Thanks again for the logfile, it is unfortunately still the same problem.
Seems to be caused by the ‘fpsgo’ driver and a missing proprietary kernel module (which isn’t included).
It’s intended to boost gaming performance, but i don’t think this has a lot of use for our smartwatches, so i turned it off.

Anyway, here is a new build that should fix this issue: PRIME_#3

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The crashing bug does seem to be fixed, and HR is working again. I tested every feature* (though not always extensively) and everything seems to be working correctly.

*Except phone features; I don’t have a SIM card in my Prime.