specification as high level programming the assl approach

... whereas the user space framework is C-based The I/O Kit maintains a database known as the I/O Catalog The I/O Catalog is a registry of all available I/O Kit classes Another database, the I/O ... and is granted the same privileges as the rest of the kernel, including the ability to directly access hardware The driver has the responsibility of initializing the hardware when the device is ... system A task (the client) is able to request services from another task (the server) The endpoints in this system are known as ports A port has associated rights, which determine if a client has access...

Ngày tải lên: 15/03/2014, 02:20

... and the MDD code from accessing the physical media simultaneously, as corruption of the disk may result if the host and embedded device try to write to the media at the same time Please see the ... Inside the interface descriptor, there are three fields that must be updated to use the MSD class driver The bInterfaceClass, bInterfaceSubClass and bInterfaceProtocol need to be updated to the ... The bInterfaceClass field needs to reflect that this device is an MSD device (MSD_INTF) The bInterfaceSubClass needs to reflect which of the subclasses defined in the MSD specification that the...

Ngày tải lên: 11/01/2016, 16:48

... mass-storage devices can function as masters on their own and can also permit a PC or other USB host to function as the master If one master adds, deletes, or changes a file and the other master ... erased or overwritten Higher -level software in the mass-storage master can also control access to data on a storage device 10 Mass Storage Basics Erasing The media in a hard drive can be erased ... data, the mass-storage class isn’t appropriate • A storage device should have one mass-storage master at a time The master, or mass-storage host, is the computer that reads and writes to the storage...

Ngày tải lên: 06/07/2014, 15:37

... increase the attach debounce interval Then enter the name of the function in the main source file that serves as the application -level event handler The USB Mass Storage Client Driver can either ... CONFIGURING THE CLASS Using the USB Configuration Tool In order to use the Mass Storage client driver for a USB Embedded Host, select the USB device type of the application on the Main tab Use the USB ... (CBW) The Command Block Wrapper is sent to the Peripheral during the Command phase of the transfer The CBW is a 31-byte packet that includes the following information: • • • • Tag to identify the...

Ngày tải lên: 11/01/2016, 16:46

... The association of the mouse with the keyboard’s internal hub and the speakers with the monitor’s internal hub is arbitrary For example, a user could instead connect the mouse to the monitor’s ... 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 bulk transfers as quickly as ... depending on the nature of the peripherals that they control: 5* Use the stream interface functions A USB device driver can expose the stream interface functions Applications can then treat the peripheral...

Ngày tải lên: 07/10/2013, 00:20

... for the driver by calling the RegisterClientSettings function so the next time that the USB device is attached, the USBD module can locate the correct driver without prompting a user In some cases ... specify the precedence order to a greater level of detail; for example, combining vendor- and device-class specifiers In these cases, the GroupX_ID values may be combined to generate other combinations ... Default\Default\Group3_ID If multiple drivers are registered at a particular precedence level, the USBD module loads the one with the most general form Built on Wednesday, October 04, 2000 ...

Ngày tải lên: 07/10/2013, 00:20

... cable – Supply Sourcing +5V The Transaction Protocol is Host Based ? Host based token polling – Data from host-to-function and function-to-host – Host handles most of the protocol complexity – ... –Non-periodic, bursty, high bandwidth utilization bursty, ? Control (Configuration messages …) –Bursty, host-initiated (bus management, Bursty, configuration) The Basic USB Model has Several Layers ... Idle Bus Address Assigned Bus Activity Address Device Configured Idle Bus Suspended Device Deconfigured Configured Bus Activity Suspended Idle Bus 11 Enumeration is the Process of Assigning Addresses...

Ngày tải lên: 13/12/2013, 00:15

... order for them to be identified as the corresponding loading and removing functions, they have to be passed as parameters to the functions module_init and module_exit The printk function has also ... the well known printf apart from the fact that it only works inside the kernel The symbol shows the high priority of the message (low number) In this way, besides getting the message in the ... user space, you can load the module as root by typing the following into the command line: # insmod nothing.ko The insmod command allows the installation of the module in the kernel However, this...

Ngày tải lên: 23/10/2013, 22:15

... order for them to be identified as the corresponding loading and removing functions, they have to be passed as parameters to the functions module_init and module_exit The printk function has also ... the well known printf apart from the fact that it only works inside the kernel The symbol shows the high priority of the message (low number) In this way, besides getting the message in the ... user space, you can load the module as root by typing the following into the command line: # insmod nothing.ko The insmod command allows the installation of the module in the kernel However, this...

Ngày tải lên: 13/12/2013, 11:15

... that there's no explicit device associated with the way the information is laid down; the filesystem type is instead a software driver, because it maps the low -level data structures to higher -level ... A module is just as powerful as a superuser shell Any security check in the system is enforced by kernel code If the kernel has security holes, then the system has holes In the official kernel ... the mapping of file operations to the SCSI communication protocol) The driver writer has to implement the mapping between the SCSI abstraction and the physical cable This mapping depends on the...

Ngày tải lên: 24/12/2013, 01:17

... using two such levels All current processors have at least two protection levels, and some, like the x86 family, have more levels; when several levels exist, the highest and lowest levels are used ... Unix, the kernel executes in the highest level (also called supervisor mode), where everything is allowed, whereas applications execute in the lowest level (the so-called user mode), where the ... refer to the execution modes as kernel space and user space These terms encompass not only the different privilege levels inherent in the two modes, but also the fact that each mode has its own...

Ngày tải lên: 24/12/2013, 01:17

... char *name); The arguments are the major number being released and the name of the associated device The kernel compares the name to the registered name for that number, if any: if they differ, ... file_operations *f_op; The operations associated with the file The kernel assigns the pointer as part of its implementation of open, and then reads it when it needs to dispatch any operations The value in ... try to obtain the semaphore Internal routines, such as scull_trimshown earlier, assume that the semaphore has already been obtained As long as these invariants hold, access to the Scull_Dev data...

Ngày tải lên: 24/12/2013, 01:17

... loglevel Based on the loglevel, the kernel may print the message to the current console, be it a text-mode terminal, a serial line printer, or a parallel printer If the priority is less than the ... modify the console loglevel using the text file /proc/sys/kernel/printk The file hosts four integer values You may be interested in the first two: the current console loglevel and the default level ... name of the /proc entry, the file permissions to apply to the entry (the value is treated as a special case and is turned to a default, world-readable mask), the proc_dir_entry pointer to the parent...

Ngày tải lên: 24/12/2013, 01:17

... arg); The inode and filp pointers are the values corresponding to the file descriptor fd passed on by the application and are the same parameters passed to the open method The cmd argument is passed ... CAP_SYS_ADMIN was chosen for this test The Implementation of the ioctl Commands The scull implementation of ioctl only transfers the configurable parameters of the device and turns out to be as easy as the ... passed from the user unchanged, and the optional arg argument is passed in the form of an unsigned long, regardless of whether it was given by the user as an integer or a pointer If the invoking...

Ngày tải lên: 24/12/2013, 01:17

... schedule_task to put a task on the queue: int schedule_task(struct tq_struct *task); task, of course, is the task to be scheduled The return value is directly from queue_task: nonzero if the task was ... to call mark_bh after the task has been queued; otherwise, the kernel may run the task queue before your task has been added The immediate queue is the fastest queue in the system it's executed ... output, the time field is the value of jiffies when the task is run, delta is the change in jiffies since the last time the task ran, interrupt is the output of the in_interrupt function, pid is the...

Ngày tải lên: 24/12/2013, 01:17

... to search a free page If the platform has no concept of high memory or it has been disabled in the kernel configuration, GFP_HIGHMEM is defined as and has no effect The mechanism behind memory ... disadvantages, not the least being the inability to ever free the buffer After a driver has taken some memory, it has no way of returning it to the pool of free pages; the pool is created after all the physical ... example of how the interface is used Reserving High RAM Addresses The last option for allocating contiguous memory areas, and possibly the easiest, is reserving a memory area at the end of physical...

Ngày tải lên: 24/12/2013, 01:17

... compiler automatically casts the values during assignment -their being unsigned helps prevent compile-time warnings No information is lost with such casts as long as the programmer assigns sensible ... addresses, and the kernel hides the details from the driver in order to ease portability The Linux kernel headers (specifically, the architecture-dependent header ) define the following ... either in the memory address space or in the I/O address space At the hardware level, there is no conceptual difference between memory regions and I/O regions: both of them are accessed by asserting...

Ngày tải lên: 24/12/2013, 01:17

... dependent, whereas stat is: the number of fields depends on the hardware underlying the kernel The number of available interrupts varies from as few as 15 on the SPARC to as many as 256 on the IA-64 ... arrived */ } As expected, this code calls queue_task without checking whether the task is already enqueued The BH, then, performs the rest of the work This BH is, in fact, the same short_do_tasklet ... the given interval (in jiffies), then returns the number of the IRQ seen since autoirq_setup was called These functions are used primarily in the network driver code, for historical reasons They...

Ngày tải lên: 24/12/2013, 01:17

... show the data size of the various C types, the datasize program has been included in the sample files provided on the O'Reilly FTP site, in the directory miscprogs This is a sample run of the ... 1.1.67, the developers couldn't change existing data structures to the new types because the compiler issues a warning when there is a type mismatch between the structure field and the value being assigned ... warnings because the format matches the type, and you won't lose data bits because the cast is either a null operation or an extension of the item to a bigger data type In practice, the data items...

Ngày tải lên: 24/12/2013, 01:17

... passed to the short driver Module Loading and Security The loading of a module into the kernel has obvious security implications, since the loaded code runs at the highest possible privilege level ... #endif The code, though hairy, has the advantage of leaving the makefile in a clean state Passing the correct flags from make, on the other hand, involves writing long command lines for the various ... for it The final check makes sure that the required feature has become available The User-Space Side The actual task of loading a module requires help from user space, for the simple reason that...

Ngày tải lên: 21/01/2014, 07:20