mtd_runtime_partition

This is some old code I wrote a few years ago to resize MTD partitions on an embedded MPC875 system while Linux is running.

It is based off of Linux MTD Utils and involves a user-space Linux utility and a MTD driver patch. I used the following links as a starting point:

• http://article.gmane.org/gmane.linux.drivers.mtd/30949
• http://article.gmane.org/gmane.linux.drivers.mtd/30950
• http://article.gmane.org/gmane.linux.drivers.mtd/30951
• http://www.linux-mtd.infradead.org/

My code assumes the following partition structure:

• mtd0: linux
• mtd1: jffs2
• mtd2: uboot config
• mtd3: must not initially exist

1. User provides the hex value for number of bytes by which to expand mtd0.
2. It works by sending a custom MTDPARTITIONSHIFT message to the driver telling it to move mtd1 over.
3. The driver actually resizes mtd0 to the desired size, but instead of shrinking mtd1 it creates a new partition mtd3 of the correct start position and size that mtd1 should have been (at the time I could not figure out how to shrink mtd1).

This allowed me to create a script that burned a new image into mtd0 and moved my JFFS2 files over from the original mtd1 to the new mtd3. On restart, the new Linux image contained an updated Device Tree with the new partition boundaries/sizes.

Usage example:

./mtd_runtime_partition 0x200000

For more details see: "Resize MTD partitions at runtime"

Note: I am no longer maintaining this, just posting it in case anyone is trying to tackle a similar issue and need a starting point.