Kernel Building for new Devices

Forum to discuss the new MK902II LE RK3288 Quad Core Linux Mini PC.

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Re: Kernel Building for new Devices

Postby bam » Fri Apr 24, 2015 4:59 pm

It's been a while before I could test this.
I have now multicast + wifi working on my box. Thanks Thorkel, that's amazing work.

But I've seen some weird behaviour:

  • After my first successful tests, I wanted to use multicast again and it didnt work anymore. It seemed that when mrouted is started in my startup script, if fails with
    Code: Select all
    mrouted: [time] can't forward: only one enabled vif
    I've been able to solve this by looping until it works (maybe the wlan comes up slowly?).
  • After a few more tests, the device started to hang about 20s after boot. Sometimes it seems to hang completely (couldn't connect on both network interfaces), sometimes I could still ssh to the wired interface, to find out that the wifi was down, unable to put it back to life without a reboot. Sometimes after a while that ssh session would hang as well.
    I have no idea what had changed since my previous tests. I noticed that the box became very hot (especially around the HDMI connector, which I don't use). I even thought maybe the rockchip shuts down to prevent overheating but I have no idea if that is possible at all...
    I flashed my original boot img back on the device, and everything worked again.
    Then I flashed Thorkels image again, and the problem seems to be solved. No clue why. I guess it may come back, and may be related to the problems Thorkel stil has with it (my wifi is encrypted).
I'll try again on Monday, and keep you updated whether it gets unreliable again...
Posts: 12
Joined: Mon Feb 16, 2015 1:48 pm

Re: Kernel Building for new Devices

Postby bam » Mon Apr 27, 2015 9:17 am

Follow up:

During boot, I use macchanger to set the MAC address of the wlan, so I'm sure I always have the correct MAC.
But it appears that the wlan MAC can change *suddenly* back to the mystical 00:90:4c:11:22:33... That's when I loose connection to my wlan interface.

After testing for a while, the device started to fully hang again, and becoming hotter than ever (can burn my finger on the hdmi connector). I'm letting it cool down now before I continue... I wonder if it would be possible to totally fry the device if I would keep it on.
I'm not sure now whether the device always becomes this hot when using the firefly kernel, or only when the MAC address changed back to 00:90:4c:11:22:33...
Posts: 12
Joined: Mon Feb 16, 2015 1:48 pm

Re: Kernel Building for new Devices

Postby bam » Tue Apr 28, 2015 12:09 pm

More follow up:

I found out that it's not always the weird MAC address that makes my device hang.
The reason why it hangs seems to be mrouted taking up so much CPU that other networking services get very sluggish and eventually so slow that network timeouts start to kick in. The high CPU load also explains the device getting so hot.

Somehow mrouted was being started too early. I can't put my finger on what exactly has to be started before mrouted is started, but if I postpone initalization of all routing functions (ip_forward, mrouted, iptables, ...) for 20s (so it happens some time after the device is fully booted), everything seems to work fine.

I think I may conclude my box is now stable with Thorkel's Firefly kernel (thanks again!), including secure wifi and multicast support.
If anything would change again after a few more hours of testing, I'll let it know here.

I still need to keep an eye on the MAC addresses though :)
Posts: 12
Joined: Mon Feb 16, 2015 1:48 pm


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