Questions tagged [embedded]

The use of Unix in embedded computer systems such as networking equipment, mobile phones, media players, set-top boxes, etc.

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How to start system shutdown or poweroff by hardware interrupt

I have a small headless embedded Linux box (NXP i.MX6, with userspace based on Debian, but am interested in more general solution). It has no HID input, no desktop stuff, just a serial console and a ...
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Rootfs permissions design

I wonder how design permissions in root file system should look for embedded device, with busybox onboard (buildroot environment). My initial concept is to remove all permissions, except x, of group (...
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how to check serial ports and write characters for testing on an embedded linux system (raptor linux with BusyBox)

I am an absolute beginner on Linux and sadly have to work with also an embedded Linux (Raptor Linux with BusyBox) for a complicated project. I have a custom made development board from a partner ...
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Unpacking and repacking of U-Boot image

Under unavoidable circumstances, I have to modify environment variables (typically accessed in the bootloader console with printenv) in the U-Boot image. The motivation is to be able to distribute ...
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How to fix MPU9250 configuration issue in device tree?

I have set up an i2c protocol which detects the mpu9250 at address 0x68. Now I want to configure the mpu and I have updated my dts file with the following lines of code: mpu9250@68 { compatible = ...
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How to use read-only permissions to prevent corruption on a writeable filesystem?

I'm developing an embedded Buildroot OS for the Raspberry Pi. This system will be turned off by simply removing power (there will be no shutdown timer), therefore it must be able to handle poweroff ...
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Embedded Linux device with high CPU Load Averages

I'm tinkering with an Embedded Linux device that is utilizing an ARM6 CPU (single core) that seems to be experiencing high CPU Load averages. This is what I am seeing after 10 minutes of being ...
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34 views

Populate environment in non-interactive session

I'm working on an embedded device that runs Yocto Poky as distro. The final product will have several applications that are started by SysVinit. There is only one root user. I have some scripts, ...
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Read-only filesystem for fastest boot?

I'm trying to figure out which read-only filesystem I should use to achieve fastest possible boot time in a stripped down embedded system using the Raspberry Pi Zero W (with the OS booting from the SD ...
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Automate driver loading question [closed]

I want to automate driver loading through hotplugging on an embedded linux system I am configuring. Through some research I've found the way I might want to do it is use udev rules to run a script, ...
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Linux system process activity suspended

Introduction: I am running a cpp application on an embedded systems device with onboard Linux, which gathers sensor data, prepares it into a JSON formatted string payload and publishes the payload on ...
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33 views

udev and kernel show no events from usb devices

I run embedded linux on a zedboard-like platform. I need to create udev rules for some various devices that will be plugged into it. I have gadgetfs and configfs on in the kernel and I've built them ...
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Disable TCP offloading on DD-WRT

We're using DDWRT with Coova Chilli and we're experiencing very bad networking performances with high speed WANs. There's a bug in Coova which is handled by disabling GRO on the LAN interface. In ...
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is there a way to disable/change kernel console from userspace

We have Beaglebone Black based custom board with 512MB RAM and 4GB eMMC. We have kernel console set as /dev/ttyS0 which is debug UART. After booting in user space, we want to disable(if possible, or ...
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Mounting MTD root file system (squashfs) on NAND flash

Device use embedded Linux version 2.6.26.5, 11 MTD partitions created on "gen_nand" at boot time. # cat /proc/mtd dev: size erasesize name mtd0: 00060000 00004000 "u-boot" mtd1: 00020000 ...
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Cant hide mouse cursor on embedded Debian [duplicate]

I am working on a Debian-based Dragon Board (410C) system. The system will produce a touch screen that triggers some functions of a car. I am trying to hide the mouse cursor in my application. ...
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How to manually mount the virtual file systems, to copy MTD partitions

Linux version 2.6.26.5, ARM Linux Kernel on embedded device, NAND-based device. I'm at Busybox rescue shell (ash), with restricted command set. How to manually mount the virtual file systems, to copy ...
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53 views

Run script after module is loaded due to device tree

Why do I want this? I use the pwm-ir-tx kernel module to blast IR signals from my embedded device. However, when the pwm kernel module is loaded during the boot process, the pin is on high. It takes ...
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How can I run a script on a Unix box without enough space to store it?

Specifically what I'd like to do is run screenfetch on my router, just for fun. Here's my disk space free: admin@RT-N66W:/tmp/home/root# df Filesystem 1K-blocks Used Available Use% ...
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73 views

Replacing busybox in an embedded device

I'm using busybox in an embedded device. The built-in busybox is rather limited. So I want try to replace busybox in place with new, more complete version. I find some info about replacing Busybox on ...
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How to configure embedded linux kernel so that the file system is visible on the host linux

I am using a powerpc, and after building and flashing the linux kernel on the device I can see the file system. But if I try to create a user or make any changes they get erased and resets to default ...
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How to use embedded device as bluetooth HSP/HFP source

I have ARM based board, kernel 4.14.67 and bluez-4.101. I want to connect bluetooth headset for playing sound from the board. My question is similar to that: https://stackoverflow.com/questions/...
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UBI layout volume not found

I am following Bootlin's embedded Linux training which aims to put an embedded Linux system on an Atmel SAMA5D4 Xplained board (theory slides, practical lab instructions) and I am stuck a putting the ...
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Reading and writing NAND flash with dd

I have an embedded device and I'd like to backup the NAND flash. From the openwrt wiki I gathered that dd is not a suitable option for dumping. You can use dd, but the dump will be garbled. However, ...
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How investigate sporadic restarts

The system is : Debian 8.1 run on embedded system with ARM7V CPU 2 GB RAM and 4 GB flash. The system sporadically restart itself couple time in day, before a week with appear very rare. What is the ...
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How to read back a fan speed?

I am on a custom board using an i.MX6. I am using Yocto (Pyro) to build my kernel (4.14.16). I am using the generic imx6qdl.dtsi device tree entry for PWM2 to drive the fan and it appears to work ...
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Are there any current videostream-player-type 32-bit distros in 2019?

I have these thin clients that are not in use I think they’d do perfect for a security camera video wall—just feed them an RTSP/RTMP URL and be done, GUI not needed. I’ve been lazily looking for ...
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201 views

Embedded Linux: setting the time without NTP

Working on a embedded Linux device built using yocto that is pulling a date via uart from another device with a satellite connection. By the time we have access to this date, we are well into a fully ...
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116 views

Asterisks locks ALSA device if chan_alsa is loaded

I am implementing an extension 900 which routes the audio to ALSA device.  I am also using mpd, which plays music through ALSA. Asterisk 15, OpenWrt 18.06 mpd.conf: log_file "syslog" ...
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1answer
204 views

Get video device on embedded Linux SoC

I'm trying to find the camera module device of an IP camera (running Linux), without much success. My main objective is to find the camera stream, so I can attach an RTSP server. Update 26/02/2019 ...
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129 views

Optimal sharing of a ring buffer between processes

We're implementing an embedded Linux system and have to provide a live updating graph on a website that shows data coming from a background process in the system. The question is how to optimally ...
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How to tell Linux where initramfs is in RAM

I'm trying to boot a Linux kernel running on top of Xen with a initramfs copied into RAM by the bootloader. In the device tree I took out a chunk of memory so the kernel will not overwrite the area ...
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Cannot Reach External Network Despite DHCP on QEMU Embedded Guest

I am trying to give an embedded router networking on QEMU. I replaced the router's kernel and modules using a generic buildroot build for the Malta CPU. I also can compile any software needed to help ...
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How deep is U-Boot's `bootm` command checking for a valid header?

TL;DR: How many ways can the bootm command fail with this error in version 1.1.4?: # bootm Booting image at 31000000 Bad Magic Number Background: I've bricked a device whose U-Boot is deeply ...
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How do I rearrange the clock tree to get the clock I need?

I am using a LVDS display on an i.MX6 DualLite. The panel is supposed to be running at a clock of 51.2MHz. I am in the process of updating to a newer Yocto (Pyro) built BSP running 4.14.16. The ...
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Import value from kernel startup code to user space

I need access to a variable, an integer, whose value is determined during startup on this embedded system. The kernel is: 2.6.35.14 and the variable I am trying to access is created an used in the ...
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Is it possible to access linux/ramdisk code memory from its running system?

I'm working with an embedded Linux device that has to be auditioned by a regulatory agency. The agency will select a few devices in the field to check if the code running is the same as auditioned. ...
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1answer
170 views

resolv.conf always empty

I have 2 different embedded devices...an old one running TI arago Linux and a Xilinx device (petalinux). On both I see the same outcome when adding dns-nameservers to /etc/network/interfaces and ...
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128 views

Interpreting /proc/partitions

I'm confused about the partitions size of a flash memory in my embedded linux device: / # cat /proc/partitions major minor #blocks name 240 0 93184 ndda 240 1 85168 ndda1 ...
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1answer
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JTAG'ing firmware into imx28

My goal here is to load a custom kernel and initramfs into the memory of the wink hub 1 based on imx28 dev board and boot it using the bootm command from u-boot shell. So, I downloaded the u-boot ...
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216 views

Flashing U-boot on beaglebone black

I got a beaglebone black which comes with u-boot linux preinstalled on the emmc. For the sake of learning I want to put u-boot on the flash myself and build linux from scratch. I have compiled u-boot, ...
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Embedded Linux: Setting up NFS (or any service) in a portable way

If I have a read-only file system, but with a read-write overlay on /etc, is it possible to run NFS service (or any other service) via a USB drive, as if the service is a portable application? Note: ...
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273 views

Rootfs versus kernel confusion [closed]

I know that they are two different entities. Rootfs is a file system which describes how to store and access data. The kernel is actual code which executes. However, isn't the kernel code stored ...
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240 views

How to bitbake copy a prebuilt static library into the sdk

Scenario: I am working with yocto linux recipes. I am trying to make a recipe which simply copies a prebuilt MyLibrary.a and its headers available on the built linux image. So, I have a libMyLibrary.a ...
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980 views

mmc0 warning on SD card bootup of linux

I get the following warning on debian linux (kernel 4.18.8) bootup of my microchip sama5d3 board: mmc0: unrecognised SCR structure version 4 mmc0: error -22 whilst initialising SD card after spewing ...
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60 views

SD card issue in embedded linux

My setup: Embedded linux version 3.x on an ARM board with a SD card. After running for a couple of months, I am getting this print in the console. I want to understand this issue, and fix it. ...
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How do I shrink a partition from the beginning? i.e. create empty space at the beginning of the block device?

I have devices with SD cards, with several partitions. The first partitions on the card is typically not mounted, and have vfat filesystem. What I want to achieve is, to create a 1MB free space just ...
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131 views

login system on a buildroot linux router [closed]

I have a Gemtek WVRTM 127ACN router / modem, If you do not touch any key during startup, linux starts automatically. It's a linux version created with buildroot, the problem is that there is not a ...
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How to check the history of processes

I'm using Debian running on a BeagleBone Black. I have a script which is supposed to execute when the system starts. The script then should run a python script. I add the command to run this script ...
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integrity check of uboot using dd

I just upgraded uboot using dd and it boot successfully : dd if=uboot_file of=/dev/mmcblk0 bs=512 The output is : 1360+1 records in 1360+1 records out I would like to read backup to ensure every ...