Updating Debian SD With Cross-Compiled Kernel

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1

I have a new BeagleBone Black (rev C) and got it booting from SD with the Debian 4GB SD image from 2015-03-01

My goal is to cross compile a custom kernel on my Linux PC and update the necessary items on the Debian SD card.

So… I got the 4.1.1 Linux kernel from here:

git clone git://github.com/beagleboard/linux.git

And then built the new kernel like this from what I gleaned on the web:

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- bb.org_defconfig
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- uImage am335x-boneblack.dtb LOADADDR=0x80008000
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- modules
mkdir MODULES
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- modules_install INSTALL_MOD_PATH=./MODULES
cd MODULES
tar czf target_modules.tgz lib

Success! Compiled with no errors. Now I have a uImage, a dtb, and a tarball of the modules to move the SD card.
BUT, when I look at the /boot dir on the Debian SD it seems to need vmlinuz and and initrd?

Can someone please advise on either how to use what I have built, or how to build what I need to update the SD card.
I’m not looking for an automated solution, I would rather understand the details at this point.

Regards,
Jalodi

2

I have a new BeagleBone Black (rev C) and got it booting from SD with the
Debian 4GB SD image from 2015-03-01

My goal is to cross compile a custom kernel on my Linux PC and update the
necessary items on the Debian SD card.

So.... I got the 4.1.1 Linux kernel from here:

  git clone git://github.com/beagleboard/linux.git

And then built the new kernel like this from what I gleaned on the web:

  make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- bb.org_defconfig
  make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- uImage am335x-boneblack.dtb
LOADADDR=0x80008000

We no longer use uImage, just build zImage

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- zImage

  make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- modules
  mkdir MODULES
  make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- modules_install
INSTALL_MOD_PATH=./MODULES
  cd MODULES
  tar czf target_modules.tgz lib

you need the *.dtb's:

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- dtbs
mkdir DTBS
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- dtbs_install
INSTALL_DTBS_PATH=./DTBS

Success! Compiled with no errors. Now I have a uImage, a dtb, and a tarball
of the modules to move the SD card.
BUT, when I look at the /boot dir on the Debian SD it seems to need vmlinuz
and and initrd?

Can someone please advise on either how to use what I have built, or how to
build what I need to update the SD card.
I'm not looking for an automated solution, I would rather understand the
details at this point.

Grab the kernel version from: cat include/generated/utsrelease.h | awk
'{print $3}' | sed 's/\"//g'

This will be "uname_r"

copy zimage as /boot/vmlinuz-$(uname_r)
copy *.dtbs as /boot/dtbs/$(uname_r)/*.dtb

copy modules as /lib/modules/$(uname_r)

boot and run, to generate the initrd...

sudo update-initramfs -ck `uname -r`

Regards,

3

btw, there's an even easier method to build/install:

make ARCH=arm LOCALVERSION=-r1 CROSS_COMPILE=arm-linux-gnueabi-
KDEB_PKGVERSION=1cross deb-pkg

Then from your bbb, just "sudo dpkg -i linux-image*.deb ; sudo reboot"

Regards,

4

Hello.

My goal is to cross compile a custom kernel on my Linux PC and update the necessary items on the Debian SD card.

So.... I got the 4.1.1 Linux kernel from here:

git clone git://github.com/beagleboard/linux.git

The following is very instructive and will also play nicer with the existing installation:

https://github.com/RobertCNelson/bb-kernel/tree/am33x-v4.1

Specifically this file for starters:

https://github.com/RobertCNelson/bb-kernel/blob/am33x-v4.1/build_kernel.sh

HTH.

5

Thanks all for the detailed replies. Also, the dpkg build is very nice - a guy could get used to it :wink:

-J

6

Hi Robert,

I was able to follow your steps and cross compile the kernel (3.8.13-xenomai-r79) and also copied the necessary modules and zimage and dtb files.

steps followed:

host$ **git clone [https://github.com/RobertCNelson/bb-kernel.git](https://github.com/RobertCNelson/bb-kernel.git)**
host$ **cd bb-kernel**
host$ **git tag**  (This shows what versions can be checked out.)
host$ **git checkout 3.8.13-xenomai-r79**

host$ **./build_kernel.sh**

after that I copied the zImage , *.dtb and modules ( also you have not seperately made a build directory , the build directory in lib/modules contains the linux source files also)

The kernel is up and running in BBB , but when I am trying to build a kernel module it is throwing me error
make[1]: Entering directory `/lib/modules/3.8.13-xenomai-r79/build’

WARNING: Symbol version dump /lib/modules/3.8.13-xenomai-r79/build/Module.symvers
is missing; modules will have no dependencies and modversions.

CC [M] /root/openvlc/reed_solomon.o
scripts/genksyms/genksyms: 1: scripts/genksyms/genksyms: Syntax error: “(” unexpected

As i can figure out there is no symversions table for the modules. There was none after running the build_kernel.sh script.
I am also supposing that the genksyms is trying to generate the symbol version information but fails to do so

Can you point out what I am doing wrong.

Regards
Prankur