Custom built Debian with RealTime kernel

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1

Hello everyone,

First, I’d like to thank you for all the support and the amazing work done on the BeagleBoneBlack.

I’m kind of a newbie here. Got my board for a few weeks on Angstrom. I’m an electronic engineering student in France and for a specific project I need a custom built distribution.

  • The distribution needs to be minimal (no extra un-needed packages)
  • I need a RealTime kernel
  • I need a late kernel (the 3.8 doesn’t have some kernel modules which I need). 3.14 for instance ?
  • I need gstreamer packages and gstreamer plugin packages to ship with the image.
  • I need to produce an image to flash the eMMC with that distro.

I have visited a lot of pages including RobertCNelson github which looks really active regarding BBB kernels. I successfully upgraded to Debian Wheezy Kernel 3.14 using this tutorial : http://datko.net/2014/03/21/bbb_upgrade_3_13/

Now I would need to generate my own image with specific packages and, most important, a real-time kernel. It seems that the Beaglebone github has a 3.8-rt branch but no 3.14-rt branch, so I guess I have to patch a “regular” 3.14 with RT-PREEMPT patches.

Could someone give me some hints and how-to’s for me to build such a thing ?

Thanks everyone for your support.

Clement C.

2

This should make it easy to get started..

https://github.com/RobertCNelson/linux-dev/commit/bd69ecb7570865a29dd24fd779fa8568ffa39e5d

Just fork the linux-dev repo,

checkout the am33x-v3.14 branch and un-comment the rt line at the
bottom of patch.sh

Regards,

3

Thanks very much Robert !

I’ve forked your repo on https://github.com/GunMan-fr/linux-dev
and uncommented the rt line in patch.sh .

Then I built the kernel using build_kernel.sh and everything worked perfectly :slight_smile: !

Now I was trying to build a debian image with build_deb.sh and it fails everytime.

I get a huge lot of this error :

ERROR: ld.so: object ‘libfakeroot-sysv.so’ from LD_PRELOAD cannot be preloaded: ignored.

and the process finally crashes with this error :

ERROR: ld.so: object ‘libfakeroot-sysv.so’ from LD_PRELOAD cannot be preloaded: ignored.

make[1]: *** [deb-pkg] Error 2
make: *** [deb-pkg] Error 2

Maybe I forgot to do something ?

Thanks very much for your help.

Clément.

4

Thanks very much Robert !

I've forked your repo on GitHub - GunMan-fr/linux-dev
and uncommented the rt line in patch.sh .

Then I built the kernel using build_kernel.sh and everything worked
perfectly :slight_smile: !

Now I was trying to build a debian image with build_deb.sh and it fails
everytime.

I get a huge lot of this error :

    ERROR: ld.so: object 'libfakeroot-sysv.so' from LD_PRELOAD cannot be
preloaded: ignored.

and the process finally crashes with this error :

    ERROR: ld.so: object 'libfakeroot-sysv.so' from LD_PRELOAD cannot be
preloaded: ignored.

this error is fine.. just a 64bit system using 32bit gcc cross compiler..

    make[1]: *** [deb-pkg] Error 2
    make: *** [deb-pkg] Error 2

Maybe I forgot to do something ?

This shouldn't happen..

But... I hardly ever test the cross "deb" just run:

./build_kernel.sh
(insert debian microSD card into host pc)
./tools/install_kernel.sh

(insert microSD into bbb)

Regards,

5

Nice one, Robert!

Is that kernel stable? Depending on the latency figures, it may work
for the Machinekit images I'm doing, which would mean no waiting for
Xenomai to make a 3.12/3.14 patch set.

6

I'm not even sure if the rt-patchset will still boot. But with how
small our v3.14.x patchset is, it's atleast worth a test.

Regards,

7

Thanks :slight_smile: !

But I guess that is to install the kernel on a live microSD the BBB will boot from. How to apply the kernel to the BBB directly on the eMMC ? (I have a debian installed on the eMMC already and there’s a debian flasher on my microSD).

It seems it has to be done via TFTP ?