Files are lost over reboot

Hi,

I am using Linux over AMCC PPC440EPx board. The Busybox image is a ram disk image that is loaded over the board.

During the booting up process, the device image is uncompressed and loaded into the ram but whatever changes that I have made are not saved to the compressed image. Instead all the settings are reset to default over reboot.

Can anyone suggest a solution to this problem?

Of course your changes are lost. You are making the changes to the uncompressed system in RAM, not to the image. Read out the image, decompress it, make your changes, compress the new image and write it back.

But the question is that how the changes will be retained. Is there any particular bash command to do so?

No, you have to do it the way I told you. Unpack the image on a different computer, make the changes you want to the unpacked files, repack them and write the new image to you embedded board.

Apart from it, is there a way to make changes on the embedded platform?

If you can mount a partition or have enough space in RAM to unpack the iomage you can make the changes there, generate a new image and write it back.

Is the original media from which the RAM disk is loaded accessible as a writable filesystem? Often on embedded systems, the bootloader fetches the kernel and initrd from a form of flash that can only be updated using something like a jtag interface. In such a case as that, you cannot store the changes back to non-volatile memory. It may also be the case that you have a small amount of writable non-volatile memory that can be used to store runtime data. In this case, you would have to modify your application so that it deliberately uses this kind of store. Your application might periodically write a configuration file or binary blob to the non-volatile media, and on boot, re-read the saved configuration to an appropriate place.
Is something like compact flash, SD card, or USB mass storage an option for you?
--- rod.

Just like theNbomr stated, if you can access the block device file where the ramdisk is written (usually flash memory), then you can change the whole ramdisk by using dd to write to that location. But you should know beforehand the address and allocated size of the ramdisk so you won't overwrite the other partition on that block device.

If you want to save some files that can be retained in your device, write them on a different writable partition that you mounted during bootup.

Regards,
archieval