Posted by cadsmith on January 27, 2008
“Linux Device Drivers, 3rd Edition”, Corbet, Hroah-Hartman & Rubini, 2005, 636pp, outlines how software used to interface machines and devices is constructed. Drivers interface application software with the hardware through kernel functionality. The release 2.6 device model supports power management, user space communication, hotplugging, device classes and object lifecycles. The authors talk about how these are built, handle memory mapping and DMA, do signaling such as interrupts, run in a device bus and multi-process environment, and are refined. Chapters have a Quick Reference summary at end of each which lists header files and C function calls. Sample driver code is given for block, character and network devices represented by sbull, scull and snull, respectively. Details such as firmware download and portability issues are discussed. Particular hardware dependencies are listed across various processors, e.g. for I/O ports. Emphasis is on most popular drivers such as PCI, USB and, to a lesser extent, ISA. Kernel debugging talks about options to enable debugging modules, printing methods (printk, console, klog, syslog, /proc/kmsg), querying (ioctrl, /proc files), watching (strace, gdb, kgdb), system faults, hangs (sysrq key, kernel profiling), the user-mode linux port (UML) which runs a kernel in a user-space process, and linux trace toolkit (LTT) which allows event tracing, dynamic probes (DProbes). See commons.
Media and network devices that exist in multi-operating system environments, or require a particular OS, may also be of interest. The Ubuntu version of Linux 2.6 can be run on Windows machines booted either from a partition, CD, or file. Wubi is a downloadable install that brings up a desktop. Lubi can convert it to a partition. Contents written to the wubi filesystem are visible to windows, after reboot, and vice-versa, or can be shared via a removable device such as USB flash, network connection, server or web site.
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Posted by cadsmith on January 24, 2008
Looked at “The Linux Programmer’s Toolbox”, Fusco, 2007, 656pp. This discusses some ways to measure use of memory, virtual memory, paging statistics, inter-process communication (IPC), multi-processing, and to do performance profiling. There are some examples of shell scripts. It also offers an overview of Linux tools for configuration, development, debugging and tuning. There are links to open-source download sites. It discusses the philosophy, derived from Unix, of combining a lot of special-purpose tools to accomplish more general-purpose functionality. There are techniques that can be used within programs themselves, or via the shell commands. The Linux architecture that makes this possible is reviewed. Alternate ways of doing some of the more complex things are shown with their relative merits, e.g. getting details about opened files such as their inodes.
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Posted by cadsmith on January 19, 2008
“Embedded Linux Primer: A Practical, Real-World Approach“, Hallinan, 2006, 576 pp, talks about developing software to run some common devices. This book is an introduction to the use of Linux for embedded device operation and software development. It has tutorials for installation, debugging, and porting. Enhancements for kernel version 2.6 are outlined. Real-time issues are highlighted, e.g. preemption and profiling. Discusses memory technology devices (MTD) subsystem and journaling flash file system (JFFS). Appendices have more details about U-Boot and BusyBox commands, SDRAM interfacing, and BDI-2000 hardware JTAG debugger. Has pointers to many open-source sites including some emerging standards. Newer types of memories and file systems might require additional sources. Test equipment is often a form of embedded device which adds applications for measurement, storage, comparison and display, for example. These can also be networked for monitoring and alerts.
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Posted by cadsmith on January 8, 2008
Reviewed “Visualizing Data”, Fry, 2007, 382pp. This book presents a seven-step process to ensure understandable information display: acquire, parse, filter, mine, represent, refine, interact. The approach is of interest to those who need to convert their frequent or complex information needs into executable code. Demonstrates the Processing front-end API for web site analysis and discusses the software design issues and approaches. Starts with simple introduction to chart drawing, curve fitting, maps, trees, and file handling techniques. Advances to applications that parse text files to show lexical maps, and display user activity across web site pages. Code can be ported from, or interface between, java and Processing or vice-versa. Techniques are shown for scraping data, downloading files, outputting to documents, handling binary streams, or using site APIs. For example, shows source behind displaying a graph of labels, in different colors and sizes, that might represent a census distribution or bookmark tag cloud. Many links refer to compatible free or product software including spreadsheets, databases and network analyzers. Some of this also applies to dataflow for inter-machine services. Author site: www.benfry.com. Demonstration video. Processing site.
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