How to read the start time data in "proc/pid/stat" to calculate the elapsed...
My aim is to write a system-call that finds the time passed from the starting time of an ongoing process. I am researching still trying to understand. Firstly I tried the code below but it returned -1,...
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 ArticleVim configuration for Linux kernel development [closed]
Kernel development is actually different from a traditional C project development (from my view, as a newbie). So, I always wonder what is the vim configuration of a kernel hacker.The most important is...
View ArticleError while raising interrupt 11 with inline asm into kernel module
I 'm trying to raise interrupt 11 with inline asm inside a kernel module LKMasm("int $0x3B"); But after this line, I read in the dmesgdo_IRQ: 1.59 No irq handler for vector This is driver code that I...
View ArticleAccess CPU model from VDSO
I'm going to implement a VDSO, which should return the CPU model of the computer. I am using Linux-5.4.6 and I've found out that the CPU model is stored in /proc/cpuinfo(I found it from this post). My...
View ArticleLinux logo is not displayed on MIPI-DSI
I am working on variscite SOM which has i. MX6 Dualite Processors with linux kernel revision 4.9.88 and Debian rootfs.I have interfaced MIPI-DSI display(Ortustech COM43H4N10ULC TFT-Displays). MIPI-DSI...
View ArticleWhy define a macro to a function with the same name?
I found the code below in https://github.com/torvalds/linux/blob/master/arch/x86/include/asm/atomic.hstatic __always_inline bool arch_atomic_sub_and_test(int i, atomic_t *v) { return...
View ArticleCan file copying be CPU-bound?
As far as I know, the CPU is usually faster than an I/O device (like the HDD, the network, RAM, etc.), so when copying a file the bottleneck is usually I/O-bound (right?).If under some condition that...
View Articlehow to get suse enterprise kernel devel packge
I'm looking for a way to download every new kernel released or kernel-devel package for suse enterprise. I found this source: http://download.opensuse.org/repositories/Kernel:/ but It seems not...
View ArticleUnderstanding container_of macro in the Linux kernel
When I was browsing the Linux kernel, I found a container_of macro which is defined as follows:#define container_of(ptr, type, member) ({ \ const typeof( ((type *)0)->member ) *__mptr = (ptr); \...
View ArticleWhat does it mean by cold cache and warm cache concept?
I read a paper and it used terms cold cache and warm cache. I googled about this terms but I didn't find something useful (only a thread here). What do these terms mean?
View Articlertprio and pri values range in Linux ps
I generate a normal process and check with cmd:ps -p [PID] -o uname, cmd, cls, pri, rtprio and have resultUSER CMD CLS PRI RTPRIO haivo ./pro1 TS 17 - as far as I know Linux just know priority from 0 -...
View ArticleAdding to my Linux a new device driver and its effect on initrd
I'm a newbie in the Linux environment, and I came a cross two concepts, the vmlinuz and initrd.What I understood that initrd determines which kernel-modules need to be loaded to support the current...
View ArticleWhy doesn't copy_user_enhanced_fast_string use AVX if it is available?
When understanding profiling result of my application (I/O-heavy) I faced copy_user_enhanced_fast_string to be one of the hottest region. It is called when copying between user and kernel spaces. The...
View ArticleHow to guarantee all DMA data write into ram when getting msi interrupt?
There are some questions that make me confused:Msi interrupt is a memory write request. Can msi ensure that all DMA data have been written into ram? or only ensure that the data has been transferred...
View ArticleLinux issue : loading and apt command problem [closed]
I have some problem with linux loading and apt command . In installation process by ISO file on Virtualbox , if i tick "yes" for " do you want network mirror ?" part then the Linux doesn't load and...
View ArticleBoth MySQL and Redis use independent processes for deployment and open ports...
MySQL and Redis are both user-mode services. Why not do it in kernel-mode service?
View ArticleLinux: Validate user credentials with api when login to computer
Is there any way to validate user's username and password by using connecting an api when they try to login in linux computer. For example when you try to login in a web site it uses remote api so i...
View Articledoes local variables get allocated on different numa node?
If we have an application which has two memory allocations malloc and numa_alloc(1) (assume we have two numa nodes 0 & 1), malloc shall be using memory on node 0 and numa_alloc shall be allocated...
View Articledisable_local_irq and kernel timers
While doing SMP porting of some of our drivers (on powerpc target) we observed some behavior on which I need you guys to shed some light:On doing a local_irq_disable() on a UP system the jiffies tend...
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