Questions tagged [kernel]

The kernel is the central component of the operating system and manages hardware, process scheduling, file systems, virtual memory paging, inter-process and network communication, etc.

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94
votes
3answers
64k views

What is rpikernelhack?

When doing an apt-get upgrade on my RPi 3, many lines of output show up like this: Adding 'diversion of /boot/bcm2708-rpi-b-plus.dtb to /usr/share/rpikernelhack/bcm2708-rpi-b-plus.dtb by ...
57
votes
1answer
60k views

How does Raspberry Pi boot?

I have a raspberry mini computer and I am wondering how that thing does whole the boot process. I can compile my own kernel and init ramdisk with my own scripts and build my own minimal linux system ...
20
votes
3answers
29k views

How compile a loadable kernel module without recompiling kernel

I have read quite a bit about how to compile a kernel module on (and for) the Raspberry Pi, but I'm still not quite able to figure out why it's not working. I have been able to build the module, but ...
19
votes
4answers
27k views

Emulating raspbian with QEMU

I'm trying to emulate raspbian on QEMU and there're plenty of guides available on internet. However, every guide points to download qemu-linux kernel from link https://xecdesign.com/downloads/linux-...
18
votes
2answers
40k views

How do I upgrade Raspbian?

I have my Raspberry Pi setup how I want, but I have an older version than what is currently available (2012-10-28-wheezy-raspbian.zip). How do I upgrade the kernel, firmware, etc.? I have upgraded ...
16
votes
2answers
41k views

What kernel parameters are available for fixing USB problems

There's a lot of problems with USB stack on Rapsberry Pi and developers are working hard to fix as many of them as possible. They introduce some kernel modules options (like dwc_otg.fiq_fix_enable) ...
16
votes
1answer
4k views

What is the difference between Raspbian kernels in official image?

In the official Raspbian "wheezy" image (2012-07-15), there are three Kernel images: kernel.img (6MB) kernel_cutdown.img (4MB) kernel_emergency.img (16MB) I'm curious what are the technical ...
15
votes
4answers
13k views

Kernel .config necessary options

I'm interested in compiling a custom kernel for the pi. I have the source from the github archive, which includes a make target for a default configuration: make ARCH=arm bcmrpi_defconfig But (as ...
15
votes
2answers
16k views

Enable monitoring mode for RTL8188CUS via USB on Raspbian

I am trying to enable monitoring mode for a USB wifi dongle with the RTL8188CUS chipset on a raspberry pi model b+ (or any raspberry pi for that matter). $ lsusb Bus 001 Device 005: ID 0bda:8176 ...
15
votes
5answers
17k views

Cannot Emulate Raspberry Pi using Qemu: Kernel Panic

I am trying to follow various guides on the Internet in order to emulate Raspberry Pi on my Fedora 22 machine. I have found this question: Emulating raspbian with QEMU and used it to find kernel-qemu ...
13
votes
4answers
20k views

Where is the kernel source for Raspbian's default 3.1.9+ kernel?

The default kernel version of Raspbian is 3.1.9+. When I try to compile an extra kernel module I have lots of error messages since the kernel header files are missing. I've checked the Raspbian ...
13
votes
3answers
16k views

Learning Linux driver development with Raspberry Pi

I'd like to write a Linux device driver for some real hardware device. What Raspberry Pi peripherals are a good fit? Basically I need the following: It must be small enough for a beginner (few month ...
12
votes
5answers
30k views

How to change the default governor?

I want to change the default governor on my pi from ondemand to performance. Is there a way of doing this?
12
votes
1answer
37k views

What is the default cmdline.txt?

My Raspbian Pi crashes to a Kernel panic when I start it up, and it suggested somewhere that an invalid cmdline.txt can cause this. What is in the cmdline.txt by default?
12
votes
2answers
18k views

building kernel image (.img) including ramdisk

I have built my Linux kernel (3.0.1) for my Raspberry Pi with these following steps: 1. Downloading kernel source 2. tar xvf source.tar.bz2 3. downloading arm cross compilation tool. 4. tar xvf arm-...
11
votes
2answers
25k views

NOOBS recovery password

I have installed a new kernel, but for some reason, it won't boot. I generated the kernel.img with imagetool-uncompressed.py, but now my Raspberry Pi fails to boot. I have made a backup of the old ...
10
votes
3answers
22k views

How to build custom OS for Raspberry pi from scratch?

I am new to kernel and embedded Linux. I have recently bought a Raspberry Pi and booted it using the Raspbian. I was fascinated by the Pi, to learn more on Embedded I have decided to make an home ...
10
votes
1answer
1k views

Control GPIO pins from C

Most of the libraries, in multiple languages, interact with the GPIO pins via /sys/class/gpio/export, /sys/class/gpio/import, /sys/class/gpio/gpio10/value, etc. However the linux kernel docs clearly ...
8
votes
3answers
383 views

Current state of I2C in Kernel and Kernel version in general

I need to use kernel drivers for some I2C peripherals, so I need kernel I2C support. As already discussed in a previous question, the current 3.1.9 kernel doesn't provide support for the SoC's I2C ...
8
votes
2answers
5k views

How to make Raspberry Pi suspend to RAM?

My application only uses Pi very occassionally and only a few seconds each time. It would be ideal if Pi supports suspend to RAM feature to save maximum energy. (I am thinking of the next step of ...
8
votes
3answers
1k views

Is it possible to run Raspberry Pi 3 with a 64-bit kernel and 32-bit user space?

I just got my hands on a Raspberry Pi 3 and I would like to start experimenting on it, specially regarding the 64-bit instruction set. I'm well aware of the pros and cons of the 32-bit versus the 64-...
8
votes
1answer
11k views

How to boot raspberry pi very quickly into Linux?

I would like my pi zero to boot quickly (under 1 second) using Linux. In that case we can pretend it is embedded controller and not standard full blown (but slow) computer. Do you have any (...
8
votes
1answer
2k views

What kernel modules and other setup are needed for using the RPi3 built in Wi-Fi?

Question I'm trying to get the Wi-Fi working (again) on my model 3. I am not using Raspbian. Which kernel config settings and loaded modules are needed for the Wi-Fi device to show up in ifconfig -a?...
7
votes
4answers
8k views

Pi 3 Raspbian “stretch” (testing) disables wifi

I have a raspberry pi 3 (which has internal WiFi), running raspbian. I decided to run it as "testing", by changing the apt list. Now, I can't use WiFi. Whenever I use wpa_supplicant, it complains ...
7
votes
5answers
14k views

GPIO Interrupt debounce

I was following this guide, Raspberry Pi GPIO interrupts in kernel space, to create a kernel module handling GPIO interrupt. The problem is that this code doesn't have software debounce implemented. ...
7
votes
2answers
2k views

How can I troubleshoot kernel panics?

My Raspberry Pi 3 has been working stably for a year now as a headless server. In the last month, it's started crashing frequently (every two days). I can attach a monitor and see that there has been ...
7
votes
1answer
15k views

iptables: nat table does not exist

I'm trying to do some NAT on my Raspi 2 running Raspbian. But when I try to do anything with the nat table in iptables, I get the following error: iptables v1.4.21: can't initialize iptables table `...
7
votes
2answers
4k views

Arm timer in kernel module with precision less than microsecond

Good evening, i'm asking your help, to understand how to use a timer in kernel module to achieve periodic task with period less than a microsecond. I was searching on the web and i've found that ...
7
votes
2answers
598 views

Kernel not updating on Raspbian under QEMU

I'm trying to update my kernel to the latest version. apt is updated and upgraded, and rpi-update finishes without error. However when I reboot, I'm still running the old kernel. Any ideas? $ uname -...
7
votes
0answers
226 views

Cannot Use SPI frequency above 500 kHz

I am running Arch Linux ARM on a Raspberry Pi 2 Model B, and I am attempting to communicate with a TFT display. I am writing a kernel module to interface with the display using SPI, and it works, but ...
6
votes
4answers
13k views

Linux headers generic package not found

I need to compile this driver, however I'm missing my kernel headers. I've tried installing them the normal way: sudo apt-get install linux-headers-generic Package 'linux-headers-generic' has no ...
6
votes
1answer
359 views

Essential parts for booting the Raspberry Pi 2

This git repository contains pre-compiled binaries of the current Raspberry Pi kernel and modules, userspace libraries, and bootloader/GPU firmware, as you can read it in the README file: https://...
6
votes
1answer
3k views

Cross-compile x86-64 code on Raspberry Pi 2

I'm doing experiments regarding compilation of the Linux kernel on various platforms, but mainly on the RPi and on x86-64 machines. There's no shortage to the links on Google describing how to compile ...
6
votes
1answer
6k views

kernel panic not syncing: VFS unknown-block 179,6 after cloning SD

I have set up my Raspbian and need to clone the SD Card to about 20 other Raspberry Pis now. I used the following command (on OS X) to clone the SD Card: sudo dd if=/dev/rdisk3 of=~/Desktop/pi.img ...
6
votes
1answer
12k views

End Kernel panic - not syncing: Attempted to kill init

I have a problem when starting my Raspberry Pi (Rasberry Pi 3 Model B). Everything worked fine. After the last reboot I've got this error. Any help would be appreciated.
6
votes
2answers
5k views

How to use the perf utility on raspbian?

I'd like to use the perf tool on my 2016-02-09 Raspbian Jessie operating system. For that, I have installed the linux-tools package (which contains perf). The kernel version in use on that image is 4....
6
votes
1answer
2k views

Raspbian kernel module segmentation fault

My Raspberry Pi currently runs 3.6.11+ #538 (obtained from uname -a), which may be the source of my issues. I'm starting to write a kernel module using the following "Hello World" code: #include <...
6
votes
0answers
972 views

Arch Linux kernel panics and firmware not working [closed]

Before the update I had linux-raspberrypi-3.1.9-33-arm and raspberrypi-firmware-20120418-2 installed. After I upgraded to raspberrypi-firmware-20120729-1, the kernel refused to boot (no kernel panics ...
5
votes
6answers
7k views

failed to start udev kernel device manager

After hardly rebooting my raspberry pi 2 running raspian it does not work anymore, when I turn it on everything works fine until this error message shows up repeatedly. [FAILED] Failed to start udev ...
5
votes
1answer
4k views

conflicting dtoverlays

I'm using a GPIO connected display 1 which requires a patched kernel and dtoverlay=4dpi-3x in /boot/config.txt I would like to use a DS18B20 temperature sensor which requires dtoverlay=w1-gpio to show ...
5
votes
2answers
8k views

How does the pi know which kernel to load?

In the boot partition there are two kernels, kernel.img and kernel7.img (for the pi 1 vs 2/3). How does the system know which to load?
5
votes
3answers
26k views

Kernel panic, unable to mount root fs on unknown-block after restart

My Raspberry Pi has been hosting a small site from home for a few days, and everything was working fine. It's completely headless, so I use SSH for everything. This morning however when I woke up, I ...
5
votes
1answer
7k views

Interrupts on the Raspberry Pi

What are the sources of interrupts on the Raspberry Pi. I currently have the model B, rev. 2.0. Example itop output: INT NAME RATE MAX 3 [ 8 Timer Tick] ...
5
votes
1answer
309 views

Kernel/Firmware as Debian package

It says on the official site that "the kernel and firmware are installed as a Debian package, and so will also get updates when using [apt-get upgrade]" I run apt-get update / apt-get dist-upgrade ...
5
votes
1answer
1k views

rpi 2: Unable to change irq affinity

I am trying to optimise getting GPIO interrupts into userspace. On the single core rpi 1 I couldn't get rid of quite some timing jitter, which makes sense as there's a lot of stuff going on on the cpu....
4
votes
3answers
3k views

How to build My own OS for the raspberry or configure an existing one

I'm using Raspbian with raspberry pi 2 ... But i want to customize it and remove some features that i don't really need , to take advantages on the performance and also to understand the procedure of ...
4
votes
2answers
812 views

Low Energy Consumption Kernel

I am thinking about compiling the kernel in order to have a low consumption configuration ready for the raspberry. Is there any configuration or .config created before compiling it with the power ...
4
votes
1answer
8k views

Why I can't update kernel version?

I have perform the following command into ssh shell: sudo apt-get upgrade sudo apt-get update sudo reboot But I still have an old kernel version, infact: pi@raspberrypi ~ $ uname -a Linux ...
4
votes
1answer
4k views

Bare Metal Assembly/C(++) Programming

I'm trying to make a small os on my Raspberry Pi. I have good assembly and strong c/c++ knowledges but I need some help. For my first experiments I worked with Qemu and it's serial output but now I ...
4
votes
2answers
1k views

RT patch is freezing

I have patched PREEMPT-RT for Raspbian Linux kernel. It works fine for normal operations (web browsing or short time programs) the following is the output of uname -a of my Rapsberry Pi 2 after ...