Compiling uClinux with kernel linux-2.6.21

Hello everybody!

Today I'll show you what I did to compile the kernel.. First of all I'm assuming that you
have already installed build-essentials and mtd-tools packages.
Now let's begin the hard work! =D









  1) Download all these packages:
  - uClinux-dist-20070130.tar.gz
  - ea-uClinux-081020.diff.gz
  - ea-v3_1_incr1.diff.gz
  - linux-2.6.21.tar.gz
  - arm-linux-tools-20061213.tar.gz
  - arm-elf-tools-20040427.sh
  - mkimage (used to generate uLinux.bin)

2) untar toolchain 1. (It will untar in the same directory where you download it. I add this path to the $PATH)

tar -zxvf arm-linux-tools-20061213.tar.gz
export PATH=$PATH:path-to-the-download-directory/usr/local/bin

Note: You can either move this directory to a directory in the PATH or add the path into the $PATH in your /home/user/.bashrc. In this way you don't have to export everytime you open a new console.

install toolchain 2.

./arm-elf-tools-20040427.sh

I had a problem when installing this toolchain. If you get an error too, edit this file and try changing:

tail +${SKIP} ${SCRIPT} | gunzip | tar xvf -

by

tail -n +43 ${SCRIPT} | gunzip | tar xvf -

Copy mkimage to /usr/local/bin and set it as executable

sudo chmod +x /usr/local/bin/mkimage

3) untar uClinux and then remove old kernel

tar -zxvf uClinux-dist-20070130.tar.gz
rm -r ./uClinux-dist/linux-2.*

4) untar linux-2.6.21 and move it to uClinux-dist

tar -zxvf linux-2.6.21
mv ./linux-2.6.21 ./uClinux-dist/linux-2.6.x

5) apply both patchs

cd ./uClinux-dist
gunzip -c ../ea-uClinux-081029.diff.gz | patch –p1
gunzip -c ../ea-v3_1_incr1.diff.gz | patch –p1

6) Configure & Compile.
a)Choose vendor Embedded Artists and board LPC2468
b)Disable i2c in device drivers > I2C support > <> I2C support

make menuconfig
make ARCH=arm CROSS_COMPILE=arm-elf-

After make, you will get an error. You must include <linux/limits.h>  in the file ./linux-2.6.x/scripts/mod/sumversion.c. Make again and go take a coffe.
The images will be in the folder ./images

-rw-r--r--  1 user user 1012K 2011-06-14 14:13 cramfs.img
-rw-r--r--  1 user user  4.2M 2011-06-14 14:13 image.bin
-rw-r--r--  1 user user     0 2011-06-14 14:13 jffs2.img
-rwxr-xr-x  1 user user  162K 2011-06-14 14:13 linux.data
-rw-r--r--  1 user user  1.1M 2011-06-14 14:13 linux.gz
-rwxr-xr-x  1 user user  2.1M 2011-06-14 14:13 linux.text
-rw-r--r--  1 user user  1.9M 2011-06-14 14:13 romfs.img
-rw-r--r--  1 user user  1.1M 2011-06-14 14:13 uLinux.bin

It's weird that we need 2 toolchain... I don't know why, but arm-linux- is used to compile the kernel (actually the kernel complains that the toolchain arm-elf is too old). It has been forced to, even if you set CROSS_COMPILE=arm-elf-. The rest is compiled with arm-elf-, so, be sure that both toolchain is in the path.

Until today, jffs2 file system can't be generated following these instructions. I'll check later! =D

Next post we'll update u-boot and boot the kernel! Wait and you'll see! =D
That's all

Marcelo Jo