Chapter 10. MTD Subsystem

In this chapter

• Enabling MTD Services page 248

• MTD Basics page 251

• MTD Partitions page 253

• MTD Utilities page 265

• Chapter Summary page 270

The Memory Technology Devices (MTD) subsystem grew out of the need to support a wide variety of memory-like devices such as Flash memory chips. Many different types of Flash chips are available, along with numerous methods to program them, partly because of the many specialized and high-performance modes that are supported. The MTD layer architecture enables the separation of the low-level device complexities from the higher-layer data organization and storage formats that use memory devices.

In this chapter, we introduce the MTD subsystem and provide some simple examples of its use. First we look at what is required of the kernel to support MTD services. We introduce some simple operations on a development workstation with MTD enabled, as a means to understand the basics of this subsystem. In this chapter, we integrate MTD and the JFFS2 file system.

We next introduce the concept of partitions as they relate to the MTD layer. We examine the details of building partitions from a bootloader and how they are detected by the Linux kernel. The chapter continues with a brief introduction to the MTD utilities. We conclude by putting it all together and booting a target board using an in-Flash JFFS2 file system image.