Access to a device is controlled by the permissions on the device file(s), and the driver is not normally involved in permissions checking. There are situations, however, where any user is granted read/write permission on the device, but some control … Continue reading
How does a driver respond if it cannot immediately satisfy the request? 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 … Continue reading
Sometimes, a shared resource is a simple integer value. Suppose your driver maintains a shared variable shrd that tells how many device operations are currently outstanding. Normally, even a simple operation such as: sgrd++; would require locking. Some processors might … Continue reading
RCS file: dist_add.c,v Working file: dist_add.c head: 1.4 branch: locks: strict access list: symbolic names: keyword substitution: kv total revisions: 4; selected revisions: 4 description: This is the base file for adding distances using structures. —————————- revision 1.4 date: 2013/12/12 … Continue reading
The PC16550D is an improved version of he original 16450 USRT functionally identical to 16450 on powerup (Character Mode). The PC16550D can be put into an alternative mode, (FIFO mode) to relieve the CPU of excessive software overhead.
Threads are “light weight processes” (LWPs). The process has five fundamental parts: code (“text”), data (VM), stack, file I/O, and signal tables. “Heavy-weight processes” (HWPs) have a significant amount of overhead when switching: all the tables have to be flushed … Continue reading
Pre-requisites In order to develop Linux device drivers, it is necessary to have an understanding of the following: C programming. Some in-depth knowledge of C programming is needed, like pointer usage, bit manipulating functions, etc. Microprocessor programming. It is necessary … Continue reading
People new to Linux often hear that it has excellent support for all kinds of cards and that the device drivers are stable and fast. Sometimes, though, setting up devices under Linux is often not all plug-and-play. Everything is a … Continue reading
All of you are requested to “add category” to your posts. Thank You
Starting to write Pseudo Driver using 2.4 kernel ? Any doughts Please let me know
Any updates for client server application using pipes