benefits of bad teaching

... released Application developers can often ignore many of the details of the workings of a computer system, because the operating system abstracts away the intricacies of the hardware platform on which ... Networking is a major subsystem of the BSD portion of XNU BSD handles most aspects of networking, such as the details of socket communication and the implementation of protocols like TCP/IP, except ... the idea of an Objective-C-based framework for drivers, but finally settled on C++ Despite the widespread use of C++ for the development of application software, Mac OS X is still one of the few...

Ngày tải lên: 15/03/2014, 02:20

... // // // // // // // // Size of this descriptor in bytes CONFIGURATION descriptor type Total length of data for this cfg Number of interfaces in this cfg Index value of this configuration Configuration ... set of descriptors that tell the computer host what type of device it is For most device classes, this is typically done through the bDeviceClass, bDeviceSubClass and bDeviceProtocol fields of ... T10 Vendor ID is not required for a device to be offered for sale Manufacturers also not have to belong to T10 to obtain a Vendor ID As of the time of this document’s publication, there is no cost...

Ngày tải lên: 11/01/2016, 16:48

... with, or arising out of, the construction, performance, or other use of the materials contained herein Many of the products and company names mentioned herein are the trademarks of their respective ... Singh of Microchip Technology, Inc., and to Alan Stern of the Rowland Institute at Harvard For their help in obtaining products used in the writing of the book, thanks to Laurent Guinnard of Ellisys, ... cylinder consists of all of the tracks with the same diameter on all of the platters the head performs the read or write operation on the media The head reads and writes a minimum of a sector’s data...

Ngày tải lên: 06/07/2014, 15:37

... the CBW) • The difference between the number of data bytes expected and the number actually transferred • Success or Failure of the command The format of the CSW is shown in Table TABLE 2: COMMAND ... removing the device from its list of attached media See the API documentation provided in the Help directory for a complete list of events The client driver requires a list of the media interface’s required ... features of our products Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act If such acts allow unauthorized access to your software...

Ngày tải lên: 11/01/2016, 16:46

... structure determines the rate of polling, which can range from through 255 milliseconds This type of transfer is typically used for devices that provide small amounts of data at sporadic, unpredictable ... delayed transfers can be acceptable for these types of device, as long as all of the data is delivered eventually However, in the absence of any other demands for bus bandwidth, Windows CE processes ... limits on the amounts of data per transfer All data transfers using USBDI transfer functions are limited to 8K of data per transfer, due to an internal limitation in Microsoft’s USB implementation...

Ngày tải lên: 07/10/2013, 00:20

... prompting a user In some cases it may be necessary to specify the precedence order to a greater level of detail; for example, combining vendor- and device-class specifiers In these cases, the GroupX_ID...

Ngày tải lên: 07/10/2013, 00:20

... ? Architecture of an Embedded USB Device ? USB Device Driver Architecture ? Case Study of a USB Device Driver ? Testing Strategies ? Issues to consider ? Conclusions 13 Types of USB Controllers ... Architecture of an Embedded USB Device ? USB Device Driver Architecture ? Case Study of a USB Device Driver ? Testing Strategies ? Issues to consider ? Conclusions 19 Architecture of an Embedded ... Utilize USB Organizations Test Resources 45 Analyzer View 46 23 Host Software Testing Strategies ? Schedule availability of Host software –USB mini-driver –Host Test Application ? Request Host Test...

Ngày tải lên: 13/12/2013, 00:15

... at the beginning of the file, it is increased by one and the number of bytes that have been properly read is given as a return value, If not at the beginning of the file, an end of file (0) is ... twenty-five pins Internally, from the point of view of the CPU, it uses three bytes of memory In a PC, the base address (the one from the first byte of the device) is usually 0x378 In this basic ... return 1; } LEDs to test the use of the parallel port In this section I’ll detail the construction of a piece of hardware that can be used to visualize the state of the parallel port with some...

Ngày tải lên: 23/10/2013, 22:15

... at the beginning of the file, it is increased by one and the number of bytes that have been properly read is given as a return value, If not at the beginning of the file, an end of file (0) is ... twenty-five pins Internally, from the point of view of the CPU, it uses three bytes of memory In a PC, the base address (the one from the first byte of the device) is usually 0x378 In this basic ... return 1; } LEDs to test the use of the parallel port In this section I’ll detail the construction of a piece of hardware that can be used to visualize the state of the parallel port with some...

Ngày tải lên: 13/12/2013, 11:15

... that is part of the PCMCIA driver package Often a client library is provided as well, which provides capabilities that not need to be implemented as part of the driver itself The scope of this book ... the CPU, is part of process management More generally, the kernel's process management activity implements the abstraction of several processes on top of a single CPU or a few of them Memory management ... end of this book, in Chapter 16, "Physical Layout of the Kernel Source", you'll find a road map to the Linux kernel, but these few paragraphs should suffice for now One of the good features of...

Ngày tải lên: 24/12/2013, 01:17

... The role of individual kernel headers will be introduced throughout the book as each of them is needed Developers working on any large software system (such as the kernel) must be aware of and ... to unload a module is one of the features of modularization that you'll most appreciate, because it helps cut down development time; you can test successive versions of your new driver without ... can control the external visibility of your symbols, as described in "The Kernel Symbol Table" later in this chapter.[7] [7]Most versions of insmod (but not all of them) export all non-static symbols...

Ngày tải lên: 24/12/2013, 01:17

... you write a huge amount of data, the overhead of the linked list is not too bad There is only one list element for every four megabytes of data, and the maximum size of the device is limited ... *buff, size_t count, loff_t *offp); ssize_t write(struct file *filp, const char *buff, size_t count, loff_t *offp); For both methods, filp is the file pointer and count is the size of the requested ... internal design of kmallocshould be taken into account We won't touch the point now, though; the innards of kmalloc are explored in "The Real Story of kmalloc" in Chapter 7, "Getting Hold of Memory"...

Ngày tải lên: 24/12/2013, 01:17

... number of bytes of data actually placed in the page buffer, just like the read implementation does for other files Other output values are *eof and *start eof is a simple flag, but the use of the ... int scull_get_info(char *buf, char **start, off_t offset, int len, int unused) { int eof = 0; return scull_read_procmem (buf, start, offset, len, &eof, NULL); } struct proc_dir_entry scull_proc_entry ... that the caller knows your new data is placed at the beginning of the buffer You should then, of course, skip the first offset bytes of data, which will have already been returned in a previous...

Ngày tải lên: 24/12/2013, 01:17

... list of Unix system calls because of the dots, which usually represent not a variable number of arguments In a real system, however, a system call can't actually have a variable number of arguments ... corresponds to one of the possible values for the direction of the transfer The type and number fields are passed as arguments, and the size field is derived by applying sizeof to the dataitem ... implementation of the hosting filesystem (see the chattrcommand) Device driver writers are interested only in the first group of commands, whose magic number is "T.'' Looking at the workings of the other...

Ngày tải lên: 24/12/2013, 01:17

... drivers often need to delay the execution of a particular piece of code for a period of time usually to allow the hardware to accomplish some task In this section we cover a number of different ... fact, task queues are often run as the result of a "software interrupt.'' When running in interrupt mode (or interrupt time) in this way, your code is subject to a number of constraints We will ... Many parts of the kernel use this queue to accomplish a wide variety of tasks As of kernel 2.4.0-test11, the actual task queue implementing the scheduler queue is hidden from the rest of the kernel...

Ngày tải lên: 24/12/2013, 01:17

... is set to the name of the type of structure that will be cached The maximum length for the name is 20 characters, including the trailing terminator The offset is the offset of the first object ... Lookaside Caches A device driver often ends up allocating many objects of the same size, over and over Given that the kernel already maintains a set of memory pools of objects that are all the same ... "Physical Layout of the Kernel Source" Note that this "allocation'' can be performed only in multiples of the page size, though the number of pages doesn't have to be a power of two The bigphysarea...

Ngày tải lên: 24/12/2013, 01:17

... execution of any subsequent read wmb guarantees ordering in write operations, and the mbinstruction guarantees both Each of these functions is a superset of barrier A typical usage of memory ... overview of the capabilities of the architectures that are supported by version 2.4 of the kernel: IA-32 (x86) The architecture supports all the functions described in this chapter Port numbers are of ... from the parallel port We'll make use of this bit as part of our implementation of an interrupt handler in Chapter 9, "Interrupt Handling" Figure 8-1 The pinout of the parallel port A Sample Driver...

Ngày tải lên: 24/12/2013, 01:17

... in the design of the hardware itself that says that interrupt lines cannot be shared The problems are on the software side With the arrival of the PCI bus, the writers of system software have ... parallel port connector on the back of your system will create this connection The pinout of the parallel port is shown in Figure 8-1 Pin is the most significant bit of the parallel data byte If you ... limited resource, particularly when there are only 15 or 16 of them The kernel keeps a registry of interrupt lines, similar to the registry of I/O ports A module is expected to request an interrupt...

Ngày tải lên: 24/12/2013, 01:17

... misc-progs directory of the sample code, and an equivalent kdataalign module is part of misc-modules This is the output of the program on several platforms and the output of the module on the ... *ptr, type _of_ struct, field_name); where ptr is a pointer to the struct list_head being used, type _of_ struct is the type of the structure containing the ptr, and field_name is the name of the list ... using HZ (the number of timer interrupts per second) For example, to check against a timeout of half a second, compare the elapsed time against HZ/2 More generally, the number of jiffies corresponding...

Ngày tải lên: 24/12/2013, 01:17

... modules.conf manpage for the full list of things that can appear in this file Here is an overview of the most common sorts of entries: [44]On older systems, this file is often called /etc/conf.modules ... version only if the software interface offered by the kernel has changed The software interface, then, can be represented by a function prototype and the exact definition of all the data structures ... about the software interface to a single 32-bit number [45] CRC means "cyclic redundancy check,'' a way of generating a short, unique number from an arbitrary amount of data The issue of version...

Ngày tải lên: 21/01/2014, 07:20