linux-device-driver

i am dealing with the concurrency managed workqueues in linux kernel 2.6.36.But i am confused about the some flags. WQ_HIGHPRI WQ_UNBOUND WQ_RESCUER WQ_CPU_INTENSIVE I create a workqueue with flag WQ_HIGHPRI and queue some work items(eg w1 w2 w3 w4,by order) to it, none of the 4 work items will sleep. Whether the 4 work items are executed by the same thread and in this situation, is any thread created? In above situation, is there any difference if WQ_UNBOUND is used? Because if you set WQ_UNBOUND , then kernel will set WQ_HIGHPRI . thank you in advance. TheCodeArtist Following excerpt

Closed . This question is opinion-based . It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post . Closed last year . I understand the 3.2 kernel is mostly an evolutionary step, but I'd like to play around with some simple device drivers for a project I'm working on. Is the info in Linux Device Drivers 3rd Ed (Corbet, Rubini and Kroah-Hartman, O'Reilly) still germane or are there major differences between how 2.6 and 3.2 do things? What do people think of this book in general? I like LDD3.

I wrote h into driver by doing echo: echo -n h /dev/mydriver When I do cat /dev/mydriver, myread function is printing h continuously. I wanted to print once. How to do that. static char m; static ssize_t myread(struct file *f, char __user *buf, size_t len, loff_t *off) { printk(KERN_INFO "Read()\n"); if (copy_to_user(buf, &m, 1) != 0) return -EFAULT; else return 1; } static ssize_t my_write(struct file *f, const char __user *buf, size_t len, loff_t *off) { printk(KERN_INFO "Write()\n"); if (copy_from_user(&c, buf + len – 1, 1) != 0) return -EFAULT; else return len; } If you want to use

I am trying to port my own driver to a Beagle board xm arm-cortex-A8 . While porting I am trying to figuring out how the .ko file actually builds. In our Makefile we only have a command to build an .o file. How is a .ko file built? Using linux- 2.6.38.8 kernel and trying to configure my driver for my kernel. The kernel kbuild module document has lots of information on how to build an external module. If you have Raspberian or some other embedded ARM Linux, you will need to get the source package for your kernel. The process differs based on whether you are compiling on the same machine the

I'm currently learning linux device drivers. I have begun with an example driver, which is just a memory buffer. My code is available on my github . I test my driver by doing this: # echo "Hello World" > /dev/mad # cat /dev/mad Hello World This is going well but when I use the redirection operator to append something (>>), the behaviour is not the one that I expected. # echo foo > /dev/mad # echo bar >> /dev/mad # cat /dev/mad bar I expected rather to have: foo bar I have implemented the llseek callback and take care of the offp in the read and write callbacks, but it still doesn't work. You