File Transfer Protocol (FTP) is a standard network protocol used for transferring files from one computer to another. It is the preferred method of exchanging files because it’s faster than other protocols like HTTP. FTP operates on the application layer … Continue reading →

File Transfer Protocol uses two TCP ports,one for control and one for data transfer.It transfer Files in a Heterogeneous Host Environment. it has two modes – 1)Active mode FTP :=Client connect from a random unprivileged port (n > 1023) to … Continue reading →

FTP:- File Transfer Protocol is a network protocol used to transfer(copy) file from one host to another using Tcp/ip network . It is basically based on client server architecture model. It has 2 basic lines between the clint and server … Continue reading →

The role of an interrupt handler is to give feedback to its device about interrupt reception and to read or write data according to the meaning of the interrupt being serviced. The first step usually consists of clearing a bit … Continue reading →

A call to read may come when no data is available, but more is expected in the future. Or a process could attempt to write, but your device is not ready to accept the data, because your output buffer is … Continue reading →

However, interrupt disabling alone does not always prevent kernel control path interleaving. Indeed, a kernel control path could raise a “Page fault” exception, which in turn could suspend the current process (and thus the corresponding kernel control path). Or again, … Continue reading →

For any section of code too large to be defined as an atomic operation, more complicated means of providing critical sections are needed. To ensure that no window is left open for a race condition to slip in, even a … Continue reading →

The easiest way to prevent race conditions is by ensuring that an operation is atomic at the chip level: the operation must be executed in a single instruction. These very small atomic operations can be found at the base of … Continue reading →

A race condition can occur when the outcome of some computation depends on how two or more interleaved kernel control paths are nested. A critical region is any section of code that should be completely executed by each kernel control … Continue reading →

Linux kernel is not preemptive, that is, a running process cannot be preempted (replaced by a higher-priority process) while it remains in Kernel Mode. In particular, the following assertions always hold in Linux: No process running in Kernel Mode may … Continue reading →

Driver Model (USB,I2C) enumerate device and bind it with driver .USB and PCI are hotplugged device and they have capability to notify OS when lets say USB (pendrive )attach.But in SOC’s based , a lot of inbuilt peripherals like host … Continue reading →

The CPU and the PCI devices need to access memory that is shared between them. This memory is used by device drivers to control the PCI devices and to pass information between them. Typically the shared memory contains control and … Continue reading →

The Serial Peripheral Interface (SPI) bus is a serial master-slave interface similar to I 2C and comes built in on many microcontrollers. It uses four wires (compared to two on I2C): Serial CLocK (SCLK), Chip Select (CS),Master Out Slave In … Continue reading →

Kobjects are the mechanism behind the sysfs virtual filesystem. For every directory found in sysfs, there is a kobject lurking somewhere within the kernel. Every kobject of interest also exports one or more attributes, which appear in that kobject’s sysfs … Continue reading →

Adding a kobject to a kset is usually done when the object is created; it is a two-step process. The kobject’s kset field must be pointed at the kset of interest; then the kobject should be passed to: int kobject_add(struct … Continue reading →