2. Constructing Embedded Linux development environment

2.0 Development steps of Embedded Linux

The following are development steps of Embedded Linux. Seeing these steps, you will know how to construct development environment for embedded linux.

This document is written on the assumption that you install "Red Hat Linux 8.0" by workstation type on your host PC. If you install other distributions on your PC, some problems related to library etc can be happened. So if you want to prevent getting into trouble and spare development time, install “Red Hat Linux 8.0” by workstation type on your PC.

If you want to know more detail things about “Red Hat Linux 8.0 Installation”, visit the bellowing site.

     http://www.redhat.com/docs/manuals/linux/RHL-8.0-Manual/install-guide/

The following is summary of each chapter.

2.1 Composing Hardware environment

MIZI-tool-box uses three cables(JTAG cable, Serial cable, Ethernet cross cable) for communication between target board and host PC. Usually each cable connects two systems when the cable needs to use. Then we introduce each cable at the following.

2.1.1 JTAG(Joint Test Access Group) cable

In here, we don’t deal with the principal or hardware configuration of JTAG. The following contents are written about the roles of JTAG when developing embedded system.
When embedded system can’t be bootable due to corruption of bootloader or when we write bootloader to flash ROM for the first time, we use JTAG cable. In those cases, we have to download bootloader from host PC to embedded system by using JTAG cable and then write the downloaded bootloader to flash ROM of embedded system.
JFlash program is used for writing bootloader (for detail, downloading bootloader from host PC, then writing bootloader to flash ROM that locates inside embedded system.)

2.1.2 Serial cable

Serial cable primary uses for communicating between host PC user and embedded system. Serial cable is used when host PC user sends commands to embedded system and when embedded system displays outputs of commands or states of itself etc. to host PC.
Its transfer rate is so slow that it is usually used to handshake small size data. But when high-speed communication devices did not exist, it sometimes used to transfer bulk data like kernel or filesystem image.

2.1.3 Ethernet cable

Serial cable has problem to handshake bulk data between two systems because of low transfer speed. To solve this problem, embedded system offers Ethernet cable that can transfer data by high-speed rate.

2.2 Constructing Software environment

2.2.0 Installing basic software development tools

(1) Installing "Red Hat Linux 8.0" by workstation type

Workstation installation installs software development tools as well as a graphical desktop environment(X-Window System). In this case, almost basic development tools will be installed, so you can install and use MIZI Linux 1.5 SDK without additional works.

(2) Already Installed "Red Hat Linux 8.0" by personal desktop type

Personal desktop installation installs a graphical desktop environment(X-Window System) and creates a system ideal for desktop use. But it doesn't install any RPMS related software development tools.
We don't supply the basic development tools that Redhat provides, so if you use MIZI Linux 1.5 SDK well, you have to find and install software development tools from Redhat site.
Software development tools include the bellowing programs as basic tools to develop;

You can get above RPMS at Redhat site.
     ftp://ftp.redhat.com:/pub/redhat/linux/8.0/en/os/i386/RedHat/RPMS

Download above RPMS at your local directory and install these by this order.

* Please update your glibc RPM package to 2.3.2 from Red Hat update site.

2.2.1 Installing “MIZI Linux SDK(Software Development Kit) for S3C2410”

After securing 1GB disk space in your host PC, make “linuette” directory.
Mount CR-Rom which “MIZI Linux SDK” is inserted at /mnt/cdrom.

Login by root account then, install all RPMs under /mnt/cdrom/RPMS directory by the following command.

If all RPMs are installed well, the basic development environment including cross-compiler is constructed in your host PC.

2.2.2 Installing Cross Compiler

To develop embedded Linux kernel, device driver, application, etc., you have to construct cross-compile environment.
Cross-compile environment is development environment that is embodied in host PC to develop linux for embedded system. To create embedded program, we would have to compile the program directly in target board or compile that in host PC for target board processor. But because of restricted resources (lack of memory or storage), compiling in target board is not easy.
So we construct cross-compile environment to compile embedded program sources in host PC instead of target board.
To construct the environment, install tool chain for target board processor. Tool chain is collection of various utilities and libraries which are needed to compile embedded program sources.

Normally, Tool chain offered by GNU is used for developing Linux.

• gcc compiler for GNU C, C++
• GNU binary utilities (assembler, linker and various object file utilities)
• GNU C library
  

The steps of installing tool chain are as following.
binutils --> header file link --> gcc (c compiler) --> glibc --> gcc (c++ compiler)
Compiling compiler is not easy because of the problem related to bootstrap.
In Here, we install tool chain easy by using RPMs of "MIZI Linux SDK".

Tool chain belonging to RPMS directory of MIZI Linux SDK

RPMS directory of MIZI Linux SDK includes not only tool chain but also the following RPMS like “minicom”, etc. These utilities that ate applied by RPM format are necessary for MIZI-tool-box developing.

2.2.3 Installing Embedded Linux GUI Toolkit, Development Kit

If Installing “MIZI Linux SDK” is finished, the total environment to develop embedded system is constructed, of course, including GUI toolkit and development Kit. But owing to “MIZI Linux SDK” is composed to MIZI-tool-box exclusively, if you use different target board, you have to compose toolkit newly.
Among embedded systems, especially PDA, smart phone, web pad, set-top box etc. use GUI which applies window system on touch screen for communicating between user and system. The developer who uses window system has to consider window manager and requirements of application developing etc.

MIZI Research provides MIZI Linux GUI library to develop applications which run on embedded linux.
MIZI Linux GUI library is provided by RPMs format that are located in RPMS directory of MIZI Linux SDK.

All files under this directory are already compiled, so you can test and use binary files directly.

2.2.4 Outline of MIZI Linux SDK

Directory structure of MIZI Linux SDK installed in host PC

If you know the structure of whole directory, you can understand development process more easily.

Now we explain each directory very simply.

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