[Updated 2:15] — Consulting firm Embedded Alley (EA) announced the first in a series of “Smart Design” webinars on flash and flash filesystem selection. The debut webinar, delivered Feb. 17 by Chief Software Architect Matt Porter, will address development on Freescale's ARM-based i.MX platform.

The “Smart Storage” webinar will cover software/hardware integration and optimization of embedded Linux on the i.MX-family system-on-chips (SoCs), and will focus on implementing flash memory storage on the platform, says EA. The presentation will be given by Porter, along with Freescale's i.MX product marketing manager, Kathleen Jachimiak. It will be hosted by Bill Weinberg, principal analyst at LinuxPundit.com, says EA.

EA has been on a “flash” kick lately, leveraging its expertise on the tricky subject of flash-memory partitioning and allocation into a new consulting practice. The practice aims to advise clients on available storage technology choices, based on the behavior of their device.

In a brief conversation with LinuxDevices, Matt Locke, COO, explained, “We help clients select a filesystem and filesystem layout. We gain an understanding of their use case through a simple conversation, or through instrumentation. We then model the expected use over several years on what we think is the best filesystem/filesystem layout.

A “pass-fail” summary graph generated by Embedded Alley's modeling tool
(Click to enlarge)

These days, EA is recommending UBIFS quite a bit, Locke said. “It's the main system we recommend for people on NAND flash,” Locke said.

UBIFS was merged into the mainline Linux kernel with last fall's 2.6.27 release. Locke explained the technology's history as follows: “IBM, Thomas Gleixner, and UBIFS's current maintainer, Artem Bityutskiy, worked on it. IBM has been using it for quite a number of years — they are actually out in production with it.”

As Locke explains it, UBI and UBIFS are actually separate technologies. UBI is a “wear-leveling” technology aimed at increasing flash lifespan, by spreading wear out across the entire device (flash can only be written/erased in large blocks, and each block withstands a finite number of cycles). UBIFS, meanwhile — formerly known as “JFFS3,” Locke said — is a new filesystem designed for using UBI.

Locke explains, “UBIFS is not just JFFS2 rewritten for UBI. It was originally called JFFS3, but it's really a new filesystem for using UBI. JFFS2 also has an option to run on top of UBI, so you can make use of JFFS2 and UBI.”

Locke adds that UBIFS can be used for “basically anything you can run on MTD.” He explains, “There's an MTD emulated layer on top of UBI, so you can continue to use normal MTD semantics to access it.”

Flood of interest in flash

Locke said EA's flash practice grew out a surge of interest from people developing personal navigation devices. “Navigation devices have these huge map files, that need to be opened in a specific way. And we had to look at how often the maps would be updated. So, we developed a canned personal navigation device type model,” he said.

Locke went on to describe some fascinating, if rather arcane, characteristics of flash memory that may not be widely understood among Linux device developers. For example, did you know that even read operations wear down flash, especially MLC flash? Lock explained, “When you get a read disturbance — an ECC error generated during a read operation — you can correct it. But, you can only correct it so many times, because doing so requires a write operation.”

The “Smart Storage” webinar will feature an overview of flash hardware and software technologies, as well as tips on SoC-based system design and flash memory analysis using EA's Application Modeling software. Attendees will learn how to determine whether “flash hardware and file systems meet product requirements for performance, bill-of-materials cost, and fielded device longevity,” says EA.

Future “Smart Design” webinars, to be held throughout 2009, will include topics such as software-hardware co-design for consumer electronics devices, as well as product test and quality assurance, says the company.

Stated Matt Porter, EA chief architect, “Today, flash memory technology is ubiquitous but not well understood. End-users rely on embedded flash memory in a wide range of multimedia devices and other applications. Developers cannot afford to take performance and longevity for granted if they want to meet user and market needs.”

Freescale's i.MX platform has been a mainstay of embedded Linux system design in recent years, with popular models including the ARM9-based i.MX27 and the ARM11 i.MX31. Freescale recently announced its i.MX51 family of processors, which incorporate ARM'S superscalar Cortex-A8 SoCs.

Availability

The one-hour webinar, “Smart Storage Choices for Intelligent Devices,” will be broadcast on February 17, starting at 7:00 AM PST, says EA. More information and registration may be found here.

 
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