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A Simple File Development System for the GESBC-9302
Paul H. Muller - Documatrix
www.documatrix-usa.com [email protected]
Disclaimer: The programs and procedures described here have been tested
and are thought to be accurate but are offered as is, with no warranty or
guarantee.
Introduction
The previous article, “Getting Started with the GESBC-9302”, described how to
set up a Debian development system, install the ARM cross-compiler, write, load
and then execute new programs. But how do you embed these programs and
make permanent changes to the GESBC-9302 Linux system? This article
describes how to set up the GESBC-9302 file system on your Debian
development platform, modify the contents of the file system, add files or
programs and then boot the GESBC-9302 from the Debian system via NFS to
test the changes. Finally, the revised file system will be written to the GESBC-
9302 flash memory so that it will be launched directly on power-up of the
GESBC-9302.
How the GESBC-9302 System is Organized
The GESBC-9302 is capable of running other operating systems in other
configurations. The GESBC-9302 Linux stock system is comprised of three main
parts: Linux kernel, file system and the bootloader. These components are
stored in permanent flash memory on board the GESBC-9302. When the board
is first powered, Redboot, the bootloader, is the first program to execute. This is
similar to the BIOS on your PC. Redboot next loads the Linux kernel from flash
and writes it into dynamic RAM.
Once the kernal is loaded, Redboot brings the Linux file system out from flash
and loads it into RAM also. The file system consists of all those directories and
files that you see in a typical Linux system: /bin /sbin /etc /home /mnt /var
/usr and so on. Linux then begins its bootup process and the GESBC-9302
eventually comes up ready for instructions from users.
For the standard Linux version all of what you see when you are logged into the
GESBC-9302 is located in dynamic RAM. You can change existing files or
transfer new files to the GESBC-9302 Linux system, but they will be lost when
the power is removed. (Of course you could mount a USB drive and save things
permanently there, but the GESBC-9302 itself normally does not store anything
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A Simple File Development System for the GESBC-9302 Paul H. Muller - Documatrix www.documatrix-usa.com [email protected] Disclaimer: The program

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Add the following command to the end of the file: ifconfig eth0 192.168.0.127 #!/bin/sh # # Set the pa

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Testing the Modified File System With the changes in place on the Debian /armfiles directory boot the GESBC-9302 via NFS to test the new file system

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Writing the New File System into the GESBC-9302 Flash Memory We now have built and tested a modified file system that includes a new default webpage

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negotiation required with tftp and this makes it compatible with the Redboot load command. Generic FTP Clinet for Windows PC In order to move the

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Now we cd to the /homewww directory and make the changes: cd home/www rm cirrus.jpg rm index.html cp /armfiles/home/www/index.html index.html

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The following screen shot shows the sequence of commands used to prepare and check the ramdisk file on the Debian PC:

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Moving the ramdisk.gz file to the Windows PC A simple FTP client will put the new ramdisk.gz file into the C:\tftp folder: The user name arm and pas

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Loading the New Ramdisk File to the GESBC-9302 Now the last steps are in sight. All we need to do is load the new ramdisk file up to the GESBC-9302

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Fortunately the Windows calculator in the scientific mode can do this. Just click on the Hex button in the upper left corner and subtract the two val

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The following commented screenshot shows the sequence of Redboot commands and the GESBC-9302 responses: -

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in its own flash.) The idea of a simple development system is that you can make and test changes to the GESBC-9302 file system and then make these c

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Conclusions The method shown here is the classic way to customize an embedded Linux system: change files and add programs to the file system, test

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Next, go to your Debian /etc directory. There should now be a file named exports. Load exports into the pico text editor and add the following line

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Testing the NFS Server The NFS server needs to be told to re-read the /etc/exports and /etc/hosts.allow files before the changes take effect. There

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Boot the GESBC-9302 in the normal way from the serial console. When you are in the GESBC filesystem, first set its IP address to 192.168.0.127, using

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Adding the GESBC-9302 File System to the Debian NFS Server Now that the Debian NFS is operational, the GESBC-9302 file system can be loaded into /arm

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When successful, you will have the entire RAM disk file system of the GESBC-9302 captured permanently to /armfiles on your Debian development machine.

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If the command is successful, Linux will unpack and load according to the file system on the Debian /armfiles directory. This sequence (somewhat e

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Modifying and Testing the GESBC-9302 File System Now that we can boot the GESBC-9302 from the Debian system, the file system can be modified and te

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