Build a uClinux kernel

$ sudo apt-get install gcc-arm-linux-gnueabi

After downloading, unzip it and copy to corresponding directories.

$ sudo apt-get -y install libncurses5-dev bc lzop u-boot-tools genromfs

$ make menuconfig

Select a vendor profile (configuration file): we choose a board Versatile-PB-noMMU from ARM.
- Reasons:
  1. It uses ARM architecture, that means we don't need to install other cross-compiler (like M68K, things will be more complicated).
  2. The machine versatilepb is supported by QEMU ARM
  3. It does not have MMU (and the impact of lacking MMU is exactly what we want to verify).

vendors/ARM/Versatile-PB-noMMU/config.arch

$ make modules CONFIG_DEBUG_INFO=y
$ make CONFIG_DEBUG_INFO=y

It may complain that some compilers (such as: arm-linux-gcc,...) are lacked, we just need to make symlinks from the current arm-linux-gnueabi-* to them:

$ cd /usr/bin
$ for i in `ls arm-linux-gnueabi-*`; do ln -sf $i arm-linux${i#arm-linux-gnueabi}; done

Remember to download toolchains for uClinux (arm-uClinux-gnueabi-*) and install them to /usr/local so that some modules can be built succesfully. (e.g. usr/net-tools/,...)
Some errors may appear when compiling modules in usr/net-tools/ directory. For some reasons, the header files can't be found (or the parameter of INCLUDE DIR in the Makefile did not work as expected). One workaround for that is: copying all *.h files from usr/net-tools and usr/net-tools/include/ to the usr/net-tools/lib directory.

$ cd [build_root]
$ cp user/net-tools/*.h user/net-tools/lib/
$ cp user/net-tools/include/*.h user/net-tools/lib/

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