cscope not working properly for out of module development
I have generated cscope database using the following command in the linux source code present in my home folder.$ make cscope I am writing my sample drivers in another folder say ~/LinuxDeviceDriversI...
View ArticleWhat are IN & OUT instructions in x86 used for?
I've encoutered these to instructions IN & OUT while reading "Understanding Linux Kernel" book. I've looked up reference manual.5.1.9 I/O InstructionsThese instructions move data between the...
View ArticleIf I do not acquire a spinlock in a softirq, is it then alright to sleep?
If I do not acquire a spinlock in softirq context, is it then alright to sleep? It is not, but how many different ways will it crash?I understand that it is incorrect to sleep after acquiring a...
View ArticleCan a process be swapped out from RAM while holding a lock?
I am trying to understand the working of process context switch and the process swapping mechanism specially when a lock is acquired by the process. Lets assume that a process A has acquired either...
View Articlefastest to rebuild the linux kernel using rpmbuild
I just built the linux kernel for CentOS using the instructions that can be found here: https://wiki.centos.org/HowTos/Custom_KernelNow, I made my changes and I would like to rebuild the kernel and...
View ArticleIs running `sync` necessary after writing a disk image?
Common way to write an image to disk looks like:dd if=file.img of=/dev/device After this command, is it necessary to run sync?sync(2) explains it only flushes filesystem caches. Since dd command is not...
View ArticleDifferences between capabilities and permissions in Linux [closed]
What are the differences between capabilities and permissions in the context of Linux Kernel?
View ArticleLinux OOM Killer and Java Process
I am often facing issue in our production environment of the Tomcat process getting killed by Linux OOM.Checking /var/log/messages it says java not tainted and java invoked OOM killer.-Xms20480m...
View ArticleWhat is the difference between rel kernel versions of Linux?
I want to know what is the difference between r34-rel, r37-rel, r38-rel, r39-rel and r40-rel in the Linux 4.4 kernel. The official kernel sources are https://github.com/android-linux-stable/msm-4.4....
View ArticleCannot find pid in system call in linux kernel
Using Ubuntu 18.04.3 x64 I upgraded the kernel from 4.x.x to 5.1.0. Then I made a new system call below. SYSCALL_DEFINE1(get_mem_info, pid_t, input_pid) { printk("Starting system call...
View ArticleRAW socket and NF_INET_POST_ROUTING
Is there a way to know in NF_INET_POST_ROUTING if the packet is generate via RAW socket:#include <sys/socket.h> #include <netinet/in.h> raw_socket = socket(AF_INET, SOCK_RAW, int protocol);...
View ArticleFatal error in #include "restart.h" library [closed]
After I try to compile the code in the linux kernel I get an error which states: sServer.c:5:10: fatal error: 'restart.h' file not foundinclude "restart.h" ^~~~~~~~~~~ 1 error generated.#include...
View ArticleClik here to view.
Why does some mmio-only arch still have inb/outb and etc in linux kernel?
afaik, port-mapped io only exists on x86, and inb, outb, inw, outw and their friends are all c functions for port-maped io. But I still find many arch under kernel/arch/ use them: Question: 1. why...
View ArticleClik here to view.
Why do some mmio-only arch still have inb/outb and etc in linux kernel?
afaik, port-mapped io only exists on x86, and inb, outb, inw, outw and their friends are all c functions for port-maped io. But I still find many arch under kernel/arch/ use them: Question: 1. why...
View ArticleWhat is the correct usage of wake_up_interruptible() in linux kernel 4.12?
I have two functions, the kernel thread which blocks on Work Kernel Thread() { set_current_state(TASK_INTERRUPTIBLE); wait_event_interruptible(..work.queue, condition)...
View ArticleUnderstanding /proc/iomem
I was looking into the "/proc/iomem" entries and have a doubt regarding the same.My Linux PC is running a Intel Xeon and has a system RAM of 4GB./proc/iomem entry of my system looks like...
View ArticleZero-copy user-space TCP send of dma_mmap_coherent() mapped memory
I'm running Linux 5.1 on a Cyclone V SoC, which is an FPGA with two ARMv7 cores in one chip. My goal is to gather lots of data from an external interface and stream (part of) this data out through a...
View ArticleU-Boot i2c detects my device (70) but Linux i2c does not. Why?
I am in the process of migrating from Linux 3.10 to a slightly newer version, Linux 4.4.8. After the migration it seems that i2c can no longer see some of my hardware. The hardware itself has not...
View ArticleUse signals to notify about an input hardware event for a push button in C?
I am developing a Linux kernel module that communicates with a user-space application through signals in order to notify about the push-button event from my embedded board, therefore, the LED turns...
View ArticleLinux Kernel Version numbering after 3.0
How are the Linux Kernel version numbers updated.Are we only following x.y version model for mainline kernels and x.y.z model for stable kernels.Can you please provide documentation for this, Googling...
View Article