kernel-module

I wrote small kernel module code as mentioned below, I am testing it in ubuntu 14.04 #include <linux/module.h> #include <linux/version.h> #include <linux/kernel.h> #include <linux/init.h> int init_mod_func(void) { printk(KERN_INFO "My module inserted\n "); return 0; } void cleanup_mod_func(void) { printk(KERN_INFO "My module removed\n "); } module_init(init_mod_func); module_exit(cleanup_mod_func); MODULE_AUTHOR("Ankur"); MODULE_DESCRIPTION("TEST MODULE"); MODULE_LICENSE("GPL"); Now when I compile and insert above module using insmod I don't see printk message in the dmesg. However after

I am having some difficulty calling a system call from inside a Linux Kernel Module. The system calls have been tested and work properly from a standard c user space program but I can't seem to get the kernel module to compile and run them. In my user program I include the following code and the system call works: #include <linux/unistd.h> #define __NR_sys_mycall 343 extern long int _syscall(long int_sysno,...)__THROW; //and then a simple call is done as such long value = syscall(__NR_sys_mycall); printf("The value is %ld\n",value); But when I try the same thing in my Linux Kernel Module I get

I am having problems getting any kernel modules to build on my machine. Whenever I build a module, modpost always says there are zero modules: MODPOST 0 modules To troubleshoot the problem, I wrote a test module (hello.c): #include <linux/module.h> /* Needed by all modules */ #include <linux/kernel.h> /* Needed for KERN_INFO */ #include <linux/init.h> /* Needed for the macros */ static int __init hello_start(void) { printk(KERN_INFO "Loading hello module...\n"); printk(KERN_INFO "Hello world\n"); return 0; } static void __exit hello_end(void) { printk(KERN_INFO "Goodbye Mr.\n"); } module_init

I'm writing a kernel module which depends on one existing kernel module. I'm building my module out of the tree (as an external module). How can I declare the dependency, so that it is recognized by depmod? While not entirely satisfying, the best I've come up with to make modprobe work is either adding an entry to modules.dep # tail -1 modules.dep ../../../../home/ctuffli/mymod/mymod.ko: kernel/drivers/scsi/libsas/libsas.ko kernel/drivers/scsi/scsi_transport_sas.ko or alternatively, symbolically linking the out-of-tree module to /lib/modules/ and let depmod figure out the dependencies # ln -s

I'm new on modules programming and I need to make a system call to retrieve the system processes and show how much CPU they are consuming. How can I make this call? Why would you implement a system call for this? You don't want to add a syscall to the existing Linux API. This is the primary Linux interface to userspace and nobody touches syscalls except top kernel developers who know what they do. If you want to get a list of processes and their parameters and real-time statuses, use /proc . Every directory that's an integer in there is an existing process ID and contains a bunch of useful

I am trying to compile a module against any source tree on the file system but I am having trouble with the Makefile. This was the original Makefile I had against the kernel specified: obj-m += new-mod.o all: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules clean: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean This Makefile would compile correctly, but goal is to have it compile against any source tree. I have tried just: obj-m += new-mod.o I thought that "all:" is assumed but I get error: make: *** No targets. Stop. I have also added: all: to the Makefile with no

I tried to install a kernel module, xfsprogs . It was successfully installed inside a container. It is really surprising, but lsmod doesn't list this module inside container or in the host system. How can a new kernel module loaded in a container?( CentOS container, Ubuntu host) Containers interact with the kernel through system calls and don't include any part of the kernel or the kernel modules inside the container. This is one of the reasons why containers designed to be light weight and portable. Also xfsprogs are user space programs and not kernel modules. How can a new kernel module

remap_pfn_range function (used in mmap call in driver) can be used to map kernel memory to user space. How is it done? Can anyone explain precise steps? Kernel Mode is a privileged mode (PM) while user space is non privileged (NPM). In PM CPU can access all memory while in NPM some memory is restricted - cannot be accessed by CPU. When remap_pfn_range is called, how is that range of memory which was restricted only to PM is now accessible to user space? Looking at remap_pfn_range code there is pgprot_t struct . This is protection mapping related struct. What is protection mapping? Is it the