Unexpected System failure of CentOS7 due to LVM partition not mounted
I have a problem with my CentOS7 system installed in Intel NUC(Intel® Core™ i7-7567U CPU @ 3.50GHz × 4 ). Last time i was not able to login to the system by any user or root password. Then I tried to...
View ArticleHow /proc/interrupts gets updated?
I would like to know how /proc/interrupts is getting up to date? is it have only irq of drivers were probed or it contains the list of all the possible irqs in the system?
View ArticleWhat is Rescheduling interrupts (RES)? What causes it? How is it handled in...
What is the difference between "RES: Rescheduling interrupts" and "LOC: Local timer interrupts"? What is responsible to fire the RES interrupt? Is LOC same as the general timer interrupt that is...
View ArticleDifference between %llx and %p while printing a pointer inside driver code...
It seems that casting a void* pointer (allocated by kmalloc) to unsigned long long changes it. Printing them with %p and %llx gives different values. Why is it so? Can anyone explain?Following is a...
View ArticleHow do Linux processes produce graphical output 60 times per second if the...
There's something I fundamentally don't understand about how multitasking works in Linux (and probably also in general). If I understand correctly, each time a process wants to change its output to the...
View ArticleGet NFS client IP address in a kernel module
I'm working on a kernel module to track the operations performed by NFS clients on my server. I can intercept the file operations using a hacky way (hijacking the vfs layer) but I can't retrieve the IP...
View ArticleLinux powerpc syscall numbers: what are spu and nospu ABI and are 32 or 64 bit
Looking into linux kernel powerpc syscall numbers in arch/powerpc/kernel/syscalls/syscall.tbl, there are 5 ABI:The <abi> can be common, spu, nospu, 64, or 32 for this file. common, 32 and 64 are...
View Articlelinux syscall open() bitmask
I want to know which purpose has the following line of code in Linux syscall int open(const char *pathname, int flags):if (flags & ~(O_RDONLY | O_WRONLY | O_CREAT | O_RDWR | O_TRUNC | O_APPEND)) {...
View ArticleWhat is the relation between the smallest kmalloc() allocation and memory...
From this post I realized that:the smallest allocation that kmalloc can handle is as big as 32 or 64 bytesandThe actual memory you get back is dependent on the system's architectureBut also memory page...
View ArticleCompiling Intel AVX instrinsics for Linux Device Driver with GCC
I am running gcc version 4.8.2 on ubuntu on corei7.Found about AVX intrinsics from google search, but I am not sure if this set of intrinsics can be used and compiled for Linux device driver. If it...
View ArticleHow can I get the iptables match "ipv4options" working in yocto sumo?
Abstract: On an embedded system running a custom Linux built with yocto sumo, I want to DROP all packets containing any IPv4 options.Tried/searched: The iptables match for the options field (iptables...
View ArticleAssign a hexadecimal address directly to a pointer in LKM code but get...
I wrote the following code:#include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/syscalls.h> #include <linux/version.h> void...
View ArticleHow to mount Rootfs on sama5d27-som1-ek board using NFS
i am trying to mount rootfs on board using NFSmy NFS export file /home/user/demo/rootfs 192.168.0.200(rw,sync,no_root_squash,no_subtree_check) my kernel arguments arebootargs=console=ttyS0,115200...
View ArticleParallel computing: how to share computing resources among users?
I am running a simulation on a Linux machine with the following specs.Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 80 On-line CPU(s) list: 0-79 Thread(s) per...
View ArticleWhat can cause a “Resource temporarily unavailable” on sock connect() command
I am debugging a Python flask application. The application runs atop uWSGI configured with 6 threads and 1 process. I am using Flask-Executor to offload some slower tasks. These tasks create a...
View ArticleHow Do I Add A Custom Attribute To The Process Table In Linux?
I am tasked with using a syscall to modify a custom attribute assigned to a process. I understand how to define the syscall and functions to call it and all of the necessary places to update for the...
View ArticleWhy does the system keep running even though it looks like the kernel crashed?
I've got a system in Azure size M64ls running CentOS 7. Sometimes in the terminal it shows what looks like a system crash but I can ssh into it and everything appears to be working just fine. What is...
View ArticleInsmod command hangs in Linux kernel
I am writing this basic character driver, where two character devices will be generated and destoryed if needed. The builds for this driver goes fine, But while loading it to kernel, sudo insmod driver...
View ArticleProgrammatically obtaining the vendor ID, product ID of a USB device on Linux...
I am currently trying to list all usb devices that are connected to a Linux system, the code will be running in the kernel, as an LSM. The lsm code is known good.I have looked at this question but it...
View ArticleHow to enable zram swap in Android Build/kernel?
How to enable zram as swap device in android linux kernel ? Is there any way create zram before init process ? kernelcmdline or kernel config.As per zram.txt no default way.
View Article