Micron FDI File System is Ideal for NOR-based Designs

Software Spotlight
Micron ® FDI File System is Ideal for NOR-based Designs
Micron ® FDI File System is Ideal for NOR-based Designs
By Kurt Sowa
Micron Software Product Manager
Micron’s Flash Data Integrator (FDI) is a full-featured Flash file system for NOR devices.
The FDI file system provides an optimal set of features for the mobile phone market. This
article discusses these features and how they benefit the phone platform.
FDI Features Ensure System Reliability
FDI includes a group of features that focus on functionality engineered to maximize the
reliability of your system.
Power Loss Recovery
One of the most important characteristics for a file system targeting mobile phones is power
safe operation. While losing data to a drained battery or dropped phone can be annoying to
users, a phone that is unable to boot or make a call after an unexpected power loss is
unacceptable.
FDI has been designed for power safe operations. Every file operation (file create, file write,
etc.) uses a state machine for power loss recovery. While it is not possible to recover data
that is not fully written to Flash memory, FDI ensures that each action is completed correctly
or it rolls back an interrupted action, thus maintaining the integrity of the file system.
Wear Leveling
Wear leveling is important to device reliability. Flash devices are internally divided into
blocks for management, and each block can be erased a finite number of times before
performance degrades. To maximize utilization, wear leveling is used to spread content
changes (for example, erases for recovering dirty space) equally over all the blocks in the
device. FDI also supports active wear leveling in legacy NOR devices, which manages both
static and dynamic data to maximize the lifespan of a Flash memory device.
Guaranteed Update
Because Flash cannot be directly modified, updating the contents of a file can be a problem
when the file volume is full. FDI ensures that file contents or attributes can be overwritten,
even when the volume is full.
Maximize Flash Device Performance with FDI
FDI’s performance features are designed to maximize the performance from your Flash
device.
Flash Throughput
System performance is important to users. FDI has been designed to minimize file system
overhead, achieving read and write speeds that are considerably faster than other file
systems. FDI can utilize up to 93% of the theoretical Flash bandwidth.
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© 2012 Micron Technology, Inc. Micron, the Micron logo, and Krypto are trademarks of Micron Technology, Inc. All other trademarks
are the property of their respective owners. All information is provided on an “AS IS” basis, without warranties of any kind.

Software Spotlight
Micron ® FDI File System is Ideal for NOR-based Designs
Figure 1. Figure 1. FDI performance versus industry Flash file systems
Background Reclaim and Format
Since NOR Flash memory devices cannot be overwritten to change data, they must be
erased prior to updating data. FDI manages both current and “dirty” data, allowing garbage
collection (reclaim) to occur in a background thread for performance. If required, garbage
collection can occur in the foreground, or be initiated manually. It can also be suspended to
let other processes execute. In addition to reclaim, formatting a volume can also occur in the
background. This allows the system to continue to be responsive to users while completing
file system operations.
Multithreading
FDI supports a multithreading system. This allows the platform to execute multiple tasks in
parallel while providing fast response. Since Flash devices have a single write state
machine, FDI serializes Flash commands at the memory technology device layer.
Shared Code and Data, Software READ-While-WRITE
NOR Flash platforms often execute code directly from the Flash device. Because Flash
partitions are not directly readable when erasing or writing data, this can present an issue
for designs that place code and data volumes in the same Flash device. FDI supports
software READ-While-WRITE, allowing code and data to seamlessly share the same
partition.
Noncontiguous Memory Addressing
FDI helps consolidate memory from multiple devices by allowing noncontiguous blocks
(blocks from several boot block architecture devices) to be combined into a single volume,
as long as the blocks are similar.
Micron® Krypto® Authenticated Operations Support
For systems where increased security is required, FDI supports Micron Flash devices that
incorporate Krypto Authenticated Operations. This functionality uses advanced encryption
standard (AES) encryption and private keys to help prevent unauthorized reads to or writes
from Flash memory.
Small Data
File systems require overhead to manage metadata, such as file names, attributes, and data
chains. For small data, this overhead can often exceed the size of the data itself. In addition
to managing files, FDI can store small data with minimal overhead via a unique parameter
API. A second option allows optimizing small data by merging it into a single element.
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© 2012 Micron Technology, Inc. Micron, the Micron logo, and Krypto are trademarks of Micron Technology, Inc. All other trademarks
are the property of their respective owners. All information is provided on an “AS IS” basis, without warranties of any kind.

Software Spotlight
Micron ® FDI File System is Ideal for NOR-based Designs
Simplify Your Design and Reduce Time-to-Market with FDI
The features described in this section are designed to simplify your design and reduce timeto-market.
Pre-OS Support
There is a benefit to being able to access the file system prior to the operating system
loading. This allows splash screens or other boot information to be stored in the file system
and simplifies the software design. FDI supports single-threaded, read-only access via a
pre-OS module.
Multivolume Support
Many platform architects prefer to segment data into several categories. FDI facilitates this
by supporting multiple file volumes. Each volume can be mounted (and formatted)
separately. This allows the system architect to designate a volume for system data and a
volume for user data. Garbage collection activities can be shared across volumes.
Modular Design
FDI is comprised of three main components. The lowest level is the MTD, which provides
the basic routines for Flash memory operations. This module allows FDI to support multiple
Flash device families without requiring changes to the core file system routines.
The next level is the FDI core. This module provides the file system functionality. The topmost
layer is the POSIX API. This provides an IEEE-standardized file system interface layer.
Having a familiar interface simplifies integration with your operating system and applications.
Figure 2. FDI architecture block diagram
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© 2012 Micron Technology, Inc. Micron, the Micron logo, and Krypto are trademarks of Micron Technology, Inc. All other trademarks
are the property of their respective owners. All information is provided on an “AS IS” basis, without warranties of any kind.

Software Spotlight
Micron ® FDI File System is Ideal for NOR-based Designs
Portability
FDI is designed to integrate quickly with a variety of RTOS platforms. FDI engineers have
experience integrating FDI with Qualcomm ® REX, Mentor Graphics ® Nucleus ® , and other
RTOS and platform operating systems. FDI has a dedicated international customer support
team to get your design to market quickly.
Quotas
Quotas allow the system to limit the space used in a volume. Quotas can be set on a group
basis, and are used to ensure that one feature or user does not use more file space than
desired.
Reservations
Reservations are often confused with quotas. Quotas limit the space that can be used.
Reservations guarantee that a minimum amount of space is available in a volume. Like
quotas, reservations are set on a group basis.
Tools
FDI has two tools that help speed development. The image builder creates a binary FDI
volume from a folder on your computer. This image can be programmed directly to Flash
memory. The image probe is used to scan an FDI image to help analyze the structure of a
volume image.
Conclusion
Micron’s FDI is an established Flash file system that provides outstanding performance and
reliability to mobile phone designers. FDI, with support from Micron engineers, provides a
robust solution and gets your designs to market faster. Visit the FDI page on micron.com for
more information about this Flash file system.
Contact your Micron representative for more information on Micron software and how it can
benefit you.
PDF: 09005aef845f5d20/Source: 09005aef845f5d2d Rev. D, 01/12
© 2012 Micron Technology, Inc. Micron, the Micron logo, and Krypto are trademarks of Micron Technology, Inc. All other trademarks
are the property of their respective owners. All information is provided on an “AS IS” basis, without warranties of any kind.