Kernel: Building V4L2 for CycloneV SoC (Embedded System)
Is it possible to build V4L2 for CycloneV SoC, ARM Cortex A9 architecture?I am trying to use a UVC USB Webcam from my CycloneV SoC?I am getting the kernel from Intel's linux-socfpga...
View Articlehow do numactl & perf change memory placement policy of child processes?
I notice numactl has some strange impact on stream benchmarkMore specifically,"numactl ./stream_c.exe" reports 40% lower memory bandwidth than "./stream_c.exe".I checked numactl source code and don't...
View ArticleC# .NET Core IoT Error for ARM embedded board : Unhandled exception....
I want to use .NET core IoT library in order to run C# code for my SAMA5D27 SOM1 EK1 ARM embedded board..NET core IoT githubI have build this .NET core project composed from project.cs source file...
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How to use the kernel hashtable API?
I'm trying to understand and use the kernel hash tables and I've already read this and this link, but I didn't understand none of them. My first question is: Why our struct has to have the struct...
View ArticleIn a VXLAN overlay network, when does sendto() complete/return?
The overlay packets have to traverse a complex path in the kernel (involving multiple network stacks) before going out to the wire. When I trace the main kernel functions involved (using eBPF), the...
View ArticleHow do I copy the contents of a file to another one in kernel space?
I need to create a copy of a file with a different name in kernel space. I'm creating a new file with filp_open (even though it's not really clear how I would specify the O_CREAT flag as it doesn't...
View ArticleLinux device node for sd card as mmcblk to access CSD register
I am trying to access the CSD (Card Specific Data) register on a SD card. The only way I know to do this is by having the linux system recognize it as a mmc device (Multi Media Card?) (eg....
View Articlevirtual box installation failing on ubuntu 18.04.4
I have tried to create docker machines on Ubuntu 18.04.4 LTS (GNU/Linux 4.15.0 x86_64)with the following command:docker-machine create test.comRunning pre-create checks...Error with pre-create check:...
View ArticleHow can we obtain a userspace file descriptor from the kernel's struct file...
I need to open a file as a struct file in kernel space and return the file's int descriptor to the userspace, and I also need to pass an int descriptor to the kernel space and be able to retrieve the...
View ArticleWhy linux kernel drivers disable the interrupt globally?
What is the need to disable the interrupt globally in linux drivers?If we do so then are we going to miss the interrupts?If yes, then is it a bad practice?
View ArticleWhy is make printing "make: Nothing to be done for `all'."? [duplicate]
This is a "Hello.c" module and "Makefile". After executing make from the woking directory I get the following message:make: Nothing to be done for `all'.This is the "Hello.c" file:#include...
View ArticleWRITE_ONCE and READ_ONCE in linux kernel
Can somebody explain the usage of WRITE_ONCE and READ_ONCE?And internally WRITE_ONCE uses a volatile qualifier. Why?How does WRITE_ONCE and READ_ONCE solve cache coherency problem?Difference between...
View ArticleHow to "hibernate" a process in Linux by storing its memory to disk and...
Is it possible to 'hibernate' a process in linux?Just like 'hibernate' in laptop, I would to write all the memory used by a process to disk, free up the RAM. And then later on, I can 'resume the...
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Kubernetes CPU throttling with CPU usage well below requests/limits
I have setup CPU and Memory Requests=Limits on all containers of my pod in order to qualify it for Guaranteed Quality of Service class. Now, look at these CPU Usage and CPU Throttling graphs for same...
View ArticleTasklet counts in /proc/softirqs increase very rapidly on USB operation in Linux
I have a legacy device with following configuration:Chipset Architecture : Intel NM10 expressCPU : Atom D2250 Dual CoreVolatile Memory : 1GBCPU core : 4USB Host controller driver : ehci-pciWhen I...
View ArticleDelay in linux socket communication
I have a userspace application (no access to source code) that sends CAN bus data using socketcan APIs.While sending the data of 64 bytes the application its facing a delay of 2 seconds between...
View ArticleWhat is the difference between tcp_max_syn_backlog and somaxconn?
I have been reading some articles about TCP implementation on Linux and I got confused, what is the difference between net.ipv4.tcp_max_syn_backlog and net.core.somaxconn and the backlog passed as...
View ArticleHow to start Android in console mode?
for a university project I am building my own Android 8 with kernel version 4.14 directly from the source files.When I start the boot process, it boots directly into Android.For better debugging I want...
View ArticleWeird behavior when passing strings to kernel module via IOCTL
I am passing a string to the IOCTL function using a pointer to a userspace struct with the parameters. My struct contains a pointer to the string, and I copy it to a local buffer to then use it. When I...
View Articledebugging driver not being loaded from device tree
ContextI'm modifying GPIO drivers to get a feel for linux device drivers (after skimming over a few books).I'm hacking the xilinx gpio driver; I already got LEDs blinking (706 eval board, ARM32) with...
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