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Questions tagged [kernel-module]

A kernel module is a run-time loadable object file that is loaded into operating system kernel to add functionality to a running kernel. Examples include device drivers and other kernel items.

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Same device node for different devices: changing the value of one node will affect another - how to fix it?

I have one question about Linux kernel device node ,the nodes example created are in the same class with different devices but the node names are the same. If I change the value of one node, another will be changed also: How to prevent…
Michael Chen
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Linux Kernel Module dev_get_drvdata Function Always Returns NULL

I have the following kernel module probe function (simplified to show the relevant parts): static int qnap_ec_probe(struct platform_device* platform_dev) { // Allocate memory for the custom data and associate with the device struct…
Harry Muscle
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Does Kernel to/from User Space Communication Need To Be Secured

I'm writing a kernel module device driver that depends on a user space helper program. I plan to have the two communicate using a character device. I was wondering though, should this communication be secured somehow to prevent any third party…
Harry Muscle
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Unkonwn Symbol error in installing kernel module

I am doing my OS assignments. The assignment requires us to write and compile a linux kernel module. I am required to use _do_fork in kernel/fork.c to fork a process. However, when I was trying to install my module into kernel space, the…
Josh Lee
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Basic Kernel HWMon Driver Module for LPC Chip?

I'm working on writing a kernel hwmon driver module for a chip that communicates over LPC (ISA style bus). I have the following code so far umode_t qnap_ec_is_visible(const void* data, enum hwmon_sensor_types type, u32 attr, int channel) { } int…
Harry Muscle
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Linux Kernel Module ignores main module file when an additional source file is added

I'm trying to build a loadable kernel module that includes another source file. I have the following in a Makefile or Kbuild file: obj-m += mymodule.o mymodule-y += other_src_file.o In this scenario, other_src_file.c will be compiled. Strangely,…
reesul
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Replace a key press in write syscall through kernel module

I am trying to replace a keyboard key press with other key. The terminal crashes as soon as I type 'A'. How do I replace the key press in write syscall. unsigned long hacked_write_test( struct pt_regs *regs ) { int r, i; unsigned int fd =…
tarun14110
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Using socket api, how to pass in an extra data structure to a fd in kernel module?

I am using a 4.x linux kernel and have a kernel module where I receive socket information when opening up a socket. if ((fd = socket(sai.sin_family, skt_type, skt_protocol)) < 0) // ... In this case, I am making use of UDP and before I transmit…
Ender
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What happens if I don't call free_irq() in the driver's exit function?

So, I wrote a basic char driver with IRQ_NO 1 for keyboard and registered a shared handler function for it. In this exit function I don't free the handler using free_irq(). In the dmesg logs I can see that the exit_function gets exectued…
agenius5
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When to write a Custom Kernel Module

Problem Statement: I have a very high bandwidth data link that is UDP based. The source of this data is not configurable, and sends on UDP a stream of datagrams. We have code that uses the standard methods for receiving data on the UDP socket that…
Scott Saito
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Why can't I get the same symbols when compiling kernel?

I'm compiling kernel (4.14.0-115.el7a.0.1.aarch64) of Centos 7.6.1810. The source file is kernel-alt-4.14.0-115.el7a.0.1.src.rpm from centos repo. What I did: mkdir /root/kernel cd /root/kernel wget…
oleotiger
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How to enable CONFIG_ARCH_USE_QUEUED_SPINLOCKS when compiling kernel for aarch64?

I'm compiling kernel of Centos 7.6.1810 for Arm. The kernel version is 4.14.0-115.el7a.0.1.aarch64. I download the source file kernel-alt-4.14.0-115.el7a.0.1.src.rpm. I wanna to compile a new kernel with different configuration from that of original…
oleotiger
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what are the two numbers for an instruction location in objdump of a kernel module?

While doing a debug for a linux device driver, I met with a situation the OS is killed with some messages. Because it doesn't come to the shell prompt, I can't run dmesg and I just have to restart the machine (it's a arm64 virtual machine). I don't…
Chan Kim
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Yocto - adding out of tree kernel module

I would like to add a wifi out-of-tree kernel module to my Yocto project. I found a layer on Open Embedded Layer Index with the driver that I need (https://layers.openembedded.org/layerindex/branch/master/layer/meta-rtlwifi/). I cannot build an…
userr019283
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incomplete type error in network device driver

I am building a simple network driver, following a tutorial, however even though net_device struct definition is said to be in #include header file, I am getting a incomplete type error, the code is just basic init_module…
TheVastNetwork
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