Describing a custom device on LPC to the Linux kernel
I have a custom multi-function device hanging off an LPC bus. Works fine with hardcoded addresses in a force-loaded kernel module, but longer-term I'd like to move towards per-function modules (there...
View ArticleLinux writing GPU drivers to print arbitrary outputs from kernel side
I have questions about GPU drivers for linux kernel. 1-) Is it possible to write a custom kernel module to print words or colors on screen like VGA using a GPU over PCI express ?2-) If it is, is it...
View ArticleStriped down kernel take long time to load on Raspberry Pi 4
I'm just trying to customize the kernel configuration for Raspberry Pi 4B, to achieve a compact system image and quick startup, but as we can see in the logs there's approximate ~4.0s to start...
View ArticleLinux user namespace - Remapping and subordinate user and group IDs
In the below docker file, base image(jenkins/jenkins) is providing a user jenkins with UID 1000 and GID 1000, within container.FROM jenkins/jenkins # Install some base packages # Use non-privileged...
View Articlehow to bind thermal sensor with cooling device using lookup table in code
i want to bind thermal sensor with cooling device ( fan ) using lookup table. I know how to do it using DTs ( device tree) but never worked using lookup table in code for same. I need help on how to do...
View ArticleWhere do we define the type of structure returned by the kernel when using...
I'm trying to use the syscall perf_vent_open to get some performance data from the system.I am currently working on periodic data retrieval using shared memory with a ring buffer.But I can't find what...
View ArticleLinux console output on multiple UARTs
My embedded board has 2 UARTs. I want to have console output on both the UARTs.In kernel/Documentation/console/console.txt it's mentioned that:you can only define one console per device type (serial,...
View ArticleHow to get a global state of the locks in Linux kernel?
I'm writing some code for the Linux kernel and I noticed the interrupts are disabled when I need them to be enabled so that a process can handle a signal. It would be fantastic if I could just obtain a...
View ArticleWhat is the "current" in Linux kernel source?
I'm studying about Linux kernel and I have a problem.I see many Linux kernel source files have current->files. So what is the current?struct file *fget(unsigned int fd) { struct file *file; struct...
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 Articlehow to bind thermal temperature sensor with emc2103 fan
how to bind an external temperature sensor with fan emc2103 in Linux. As emc2103 has its own temperature sensor which its use to control fan speed. but I want to control fan speed based on CPU...
View ArticleDisabling the linux virtual console completely
I have a raspberry pi, which listens on the network and plays videos on hdmi when told. This is accomplished with omxplayer, without X11.I want to make the screen completely back at all times except...
View ArticleHow to launch container with user namespace configuration?
In the below docker file, base image(jenkins/jenkins) is providing a user jenkins with UID 1000 and GID 1000, within container.FROM jenkins/jenkins # Install some base packages # Use non-privileged...
View ArticleWhat is the mincore syscall used for in userland applications?
What is Linux'mincore(2) useful for in userland applications? Why is it exposed to non-privileged users?I can imagine some databases taking advantage of knowing which pages are cached but what are some...
View ArticleHow does Linux link device file with device driver? Does open() syscall...
I have a question about Linux device file and drivers, with my current understanding as the following:When a user calls open() on some device file, at some point of time kernel will ask inode of the...
View ArticleCopying more than 1 page sized buffers from kernel space to user space using...
I have created a sysfs entry with store and show functions. I'd like to use show function to copy buffers of size > PAGE_SIZE from the kernel space to userspace.I am able to currently copy buffers...
View ArticleWhats the difference between "id" and "stream_id" in the structure returned...
I am trying to write a piece of code using the perf_event_open syscall. But I don't understand the real difference between id and stream_id fields in the structure returned in my memory map.This...
View ArticleRegular audio glitches on Linux with Scarlett 3rd gen USB interface [closed]
I have a Scarlett 18i20 audio interface running well on a Samsung laptop with Linux Mint 19.3 Tricia and with the 5.0.21-rt16 real time kernel with fully preemptive configuration.The same set up on a...
View ArticleClik here to view.
Perf on MIPS debug kernel with frame_pointer
I am trying to use perf tool for MIPS & facing some trouble in getting back-stacks.How can I enable FRAME_POINTER for mips ? I have DEBUG_KERNEL enabled, but it looks like -fno-omit-frame-pointer...
View ArticleLinux timer hangs sometime and stops at 1ns
I have an embedded board with PowerPC 5200 running Realtime Linux with version 2.6.33.My application is using one high-resolution timer in Linux for alarms. This timer sometimes didn’t expire. The...
View Article
