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Tag: kernel

How to disable cache memory in kernel modules

I’am currently trying to develop a Linux driver to use a custom module developed in FPGA. For that, I use a Xilinx Zynq SoC with a Linux distribution that runs on the 2 ARM cores and my VHDL modules are implemented on the FPGA part, but this is not really important to understand my problem. My FPGA module writes directly

Which system calls are not interrupted by a signal?

AFAIK, most of the system calls on linux/unix are interrupted when a signal is received. According to the blog post below, there are some system calls that are not interrupted: In general function that return immediately (don’t wait for any I/O operation to complete or sleep) are not interruptible like socket(2) which just allocates a socket and doesn’t wait for

Linux input driver not working properly

I have written a small linux input driver which reads the state of a gpio. The driver registers OK and also the interrupt gets fired, however the events are not always displayed. Driver runs on Beagleboneblack with Android and kernel version 3.8.13 To test it I do either: cat /dev/input/event2 Or run an user space app that I wrote. The

Does the qstr struct in a kernel dentry hold the filename of a Linux file?

Below is a snippet of the Linux dentry struct from http://lxr.free-electrons.com/source/include/linux/dcache.h#L150. The struct contains a member struct qstr d_name – definition below. I would like to know if this is the name of the particular file that would correspond to this dentry at runtime. What confuses me is that proc/PID/maps uses struct dentry_operations -> d_name (another member of dentry) to

Linux Kernel – What does it mean to “put” an inode?

I saw the following comment atop the iput function: To me that sounds like it’s not “putting” anything, but “dropping” it. I’m aware of the drop_inode function, which gets called from iput in some cases, so the usage of the term “put” is even more confusing here. Answer put is common terminology in kernel code for decrementing an object’s reference

modify the kernel version information in the menuconfig

I downloaded the kernel source and by typing the following command I can see the linux kernel version is 3.02.02 for example. However, due to some reasons, I have to change it to say… 3.01.01-12-generic I found the appending option in the menuconfig but this does not meet my need. Please let me know if this is doable and how

sys_ functions in syscalls.h are undefined

I’m just making a kernel module. And I meet this warnings: How can I fix this problem? This is my codes: And my workspace is Ubuntu 3.13.0-66-generic. I need to use file descriptor. So, I can’t use filp_ functions(like filp_open). Edit1: My Makefile: obj-m += NAME.o Answer Calling system calls(sys_* functions) from the kernel code is not a good idea.

How to Obtain Youngest Child’s PID from task_struct

I’m working on a project that involves writing a new system call for Linux 3.18.20. This system call is supposed to store various information about the currently running process in a newly defined struct. One of the fields of the struct is the PID of the process’s youngest child, and I’ve been searching for information about this in the struct

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