Kernel boots in Emergency mode after adding system calls
I have been given the task of modifying slob.c to use a best-fit algorithm when doing memory allocation. What I'm having trouble with is implementing a syscall that returns the amount of free memory...
View ArticleHow nl80211 library & cfg80211 work?
I want to learn about how nl80211 and cfg80211 works in detail. Function flow, how nl80211 interact with network tools like wpa_supplicant, iw. Plz suggest me some useful links or books to refer.
View ArticleWhere are DECLARE_PER_CPU variables stored in kernel
I am trying to understand how current macro retrieves struct task_struct of the process.I am trying to understand for x86 architecture, and after exploring kernel source, struck at the following...
View Articleerror: expected declaration specifiers or ‘...’ before ‘off_t' [closed]
void *orig_mmap(void *addr, size_t lenght, int prot, int flags, int fd, off_t offset); I don't understand the off_t indentifier and it is causing the error I mention above.
View ArticleInterrupt parameter: device tree configuration?
I am currently writing a device tree node to configure SCISIS752 Dual Channel UART with I2C which is connected to the slave address 0x4d. I am also using a clock of 1.8432MHz. The IRQ pin of SCISIS752...
View ArticleAws ec2 patch upgrade for Linux 7 using automation
Hi are u aware like what is best approach to upgrade the kernal patches on AWS ec2 instances using automation tool like terraform, cloud formation or any best practices. Where I can upgrade and roll...
View ArticleIs there a way to switch to another process context from linux kernel module
I try to change the "current" process to another task as the scheduler do it but it's more complicated than I thought. In other words, I'm looking for KeStackAttachProcess linux equivalent.Flow:...
View ArticleCannot check for null getting error in an if statement
I have a system call for the Linux kernel. When checking for null in an if statement, the process terminates:unable to handle kernel null pointer reference at [position]The faulty code below:struct...
View ArticleHow to enable Google Container Optimized OS swap limit support
I'm running Kubernetes/Docker on Google Container Optimized OS on a GCE instance. When I run docker info it says$ docker info Containers: 116 Running: 97 Paused: 0 Stopped: 19 Images: 8 Server Version:...
View ArticleWhat kernel options is Google's Container Optimized OS built with?
I'm having trouble finding the kernel options that Google's Container Optimized OS is built with. I tried looking at the usual locations like boot/config-* and /proc/config.gz, but didn't find...
View ArticleWhy doesnt apt-get update work on kali linux?
I am trying to update Kali Linux but the update is not working.I tried reinstalling the system two times but it doesn't work anyway Here it is what happensroot@kali:~# apt-get update Reading package...
View ArticleWhat is the maximum buffer size that we can pass using nl? If we increase the...
I am working on an application(ARM platform) that uses netlink messages to pass a buffer of size 8k to kernel space driver to fetch some data from the driver. I have allocated the required memory for...
View ArticleProblem In sending signals from my Linux kernel module to user space application
I am using an embedded board with Linux operating system.This board has a push button and Led.Button file path is : /dev/input/event0 , and has a code 260 .Led file Path is : /sys/class/leds .I want to...
View ArticleThe maximum buffer size that we can pass using netlink and PAGE_SIZE...
I am working on an application (ARM platform) that uses netlink messages to pass a buffer of size 8k to kernel space driver to fetch some data from the driver. I have allocated the required memory for...
View ArticleWalking page tables of a process in Linux
i'm trying to navigate the page tables for a process in linux. In a kernel module i realized the following function:static struct page *walk_page_table(unsigned long addr) { pgd_t *pgd; pte_t *ptep,...
View ArticleCgroup memory controller
I have done a simple experiment with both v1 and v2 cgroup memory controller on a 4.18 kernel that looks like this.I set the maximum memory limit accordingly. For v1 I write into the...
View ArticleKernel Oops page fault error codes for ARM
What does error code after Oops give information about the panic in arm ex. Oops: 17 [#1] PREEMPT SMP what 17 give information in this case. In x86 it represents -bit 0 == 0: no page found 1:...
View ArticleHow do I use ioctl() to manipulate my kernel module?
So I'm trying to write a kernel module that uses the linux/timer.h file. I got it to work inside just the module, and now I am trying to get it to work from a user program.Here is my kernel...
View ArticleHow the util of iostat is computed?
iostat -x -d can display many i/o statistic info. For util of iostat, the explanation is : Percentage of CPU time during which I/O requests were issued to the device (band-width utilization for the...
View ArticleRestrict folder access via ssh [closed]
How to restrict a folder's access from a user The following link provides this description with sftp: https://www.tecmint.com/restrict-ssh-user-to-directory-using-chrooted-jail/ Is there a solution for...
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