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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16
votes
4answers
12k views

What are the minimum root filesystem applications that are required to fully boot linux?

It's a question about user space applications, but hear me out! Three "applications", so to speak, are required to boot a functional distribution of Linux: Bootloader - For embedded typically that's ...
21
votes
3answers
44k views

How to extract files from uImage?

Buildroot is generating images for an embedded device where they should run. This is working very well. In those images, the rootfs is included. Due to some research, I'd like to look into that ...
18
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3answers
27k views

Attaching USB-Serial device with custom PID to ttyUSB0 on embedded

I'm attempting to get an FTDI USB-Serial device with a custom PID to automatically (or even manually) attach to ttyUSB%n, without much success. The device's normal VID/PID is 0403/6001. When ...
8
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3answers
703 views

Open Source router firmware options?

What distro's exist that are designed for routers? Please include the following link to the project page link to supported hardware list what distinguishes them, why pick this option friendly web ...
2
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1answer
4k views

Debian and Systemd: breaking ordering cycle error [closed]

I'm a new embedded developer I'm trying to make systemd 37 work with freescale vybrid board (A5 and M4) running on linux-3.0 After boot with some breaking ordering cycle error, I check with ps ax ...
36
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5answers
18k views

Corruption-proof SD card filesystem for embedded Linux?

Recently we had a rather unpleasant situation with our customer - Raspberry Pi based "kiosk" used to display remote sensing data (nothing more fancy than a kiosk mode browser displaying a self-...
21
votes
5answers
94k views

How to check password with Linux?

I want to check, from the linux command line, if a given cleartext password is the same of a crypted password on a /etc/shadow (I need this to authenticate web users. I'm running an embedded linux.) ...
16
votes
3answers
22k views

How do I have Linux boot with a rootfs in RAM?

The rootfs is a squashfs image and my bootloader is loading it into some address in SDRAM. What parameters do I need to pass to the kernel so It can mount the rootfs from there? Squashfs support is ...
5
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2answers
15k views

How do I cause a watchdog reset of my embedded Linux device

Is there a command like vi > out vi | out That I could use to cause a watchdog reset of my embedded linux device?
11
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5answers
1k views

Which minimal but extendable Linux distribution to choose

I need an extendable Linux distribution which I can easily reduce in size so much that it fits into a 64 mb CF card. In this stripped version it will run on a Via C7 and needed is Kernel, networking,...
3
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1answer
1k views

WIFI over SDIO over USB - Do I have to reflect that in the device tree?

I am currently extending an embedded hardware platform which runs a linux kernel 3.16. I want to connect an external SDIO controller to the USB bus, and then run a WIFI module using that SDIO ...
3
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1answer
2k views

Relative path to anything not working (while running from initramfs)

I'm working in an embedded Linux system trying to get it booting its root file system in ram using initramfs. The system comes up for the most part but then has trouble in the init scripts. I've ...
4
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3answers
1k views

Debugging ethernet before NFS boot

I'm trying to boot Linux from U-boot on an embedded ARM board using a filesystem on a remote machine served via NFS. It appears that the ethernet connection is not coming up correctly, which results ...
4
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1answer
4k views

Checking linux Kernel for RT-Preempt Patch

How to know whether a particular patch is applied to the kernel? Especially RT-Preempt Patch.
2
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1answer
1k views

What are the Linux shells that allow network traffic management (sending/receiving data to/from `/dev/tcp/host/port`) via redirectors?

Following this Bash tutorial, I have succeded in obtaining the code of a web page issuing simple commands by using this method: $ exec 3<>/dev/tcp/www.google.com/80 $ echo -e "GET / HTTP/1.1\n\...
2
votes
1answer
679 views

is there a way to atomically move file and directory from tempfs to ext4 partition on eMMC

We have beaglebone black based custom board with 256MB RAM and 4GB eMMC. Board runs Linux kernel 4.9 we are running into a situation where we create a file in tempfs and then after validation, we ...
15
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2answers
8k views

Is using a read only root file system a good idea for embedded setup?

I have been tasked with running Linux as an operating system on an embedded device. The target has an x86 processor and has 8 GB CompactFlash device for storage. I have managed to use buildroot to ...
13
votes
2answers
10k views

Is it possible for a daemon (i.e. background) process to look for key-presses from a USB keyboard?

I'm working on an embedded Linux project where I will be developing a program that will run automatically on bootup and interact with the user via a character display and some sort of button array. ...
7
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2answers
4k views

How can one force a re-scan of an SDIO bus from Linux user space?

On an embedded Linux platform, I have a network adapter attached to an SDIO interface. There is no Card Detect signal on this particular bus. If for instance, I turn the network adapter power on or ...
9
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4answers
5k views

What filesystem offers best protection for securing data against corruption due to power loss?

I am running a small uClibc and busybox based embedded system on an x86 device. I am using an initramfs but I also mounting a custom ext3 directory on a compact flash device in IDE mode that I am ...
2
votes
1answer
7k views

uboot write kernel into mmc partition

I want to write a Linux kernel with U-Boot into a mmc hwpartition of an eMMC storage on an i.MX6 board: TX6UL U-Boot > mmc info Device: FSL_SDHC Manufacturer ID: 11 OEM: 100 Name: 004G6 Tran ...
7
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4answers
3k views

How do I create small disk image with large partitions

I am building a disk image for an embedded system (to be placed on an 4GB SD card). I want the system to have two partitions. A 'Root'(200Mb), and a 'Data' partition(800Mb). I create an empty 1GB ...
4
votes
1answer
305 views

How do you ensure physical network interfaces always get the same interface name across reboots on an embedded Linux system?

For an embedded Linux system, if I have two or more network interfaces, how do I ensure that they always get the same interface names every boot In other words, I want, for example, eth0 to always ...
4
votes
1answer
8k views

/dev/console dynamic redirection

Is it possible to dynamically redirect all data sent to /dev/console into something else (for example - to /dev/null, /dev/tty9 or even /dev/null)? Of course, it can be done statically via console=...
4
votes
3answers
6k views

Reading EDID from EEPROM

From the link: http://en.wikipedia.org/wiki/Extended_display_identification_data The EDID is often stored in the monitor in a memory device called a serial PROM (programmable read-only memory) or ...
3
votes
1answer
2k views

How do I install another distro on a linux DVR

I was fiddling with an old DVR and discovered it had telnet unblocked. So I ran ncrack and after gaining access started looking around. It seems to be running some custom version of Linux. Not many ...
12
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2answers
37k views

How to list the kernel Device Tree [duplicate]

I am using an embedded Arm with a Debian build. How does one list the compiled devices from the device tree? I want to see if a device is already supported. For those reading this, the "Device Tree" ...
10
votes
1answer
3k views

How to build the GCC cross compiler for Cross Linux From Scratch (CLFS) for Beagleboard?

Currently I try to build a embedded Linux from scratch with the instructions from Cross Linux from Scratch. Everything worked fine until I tried to compile the GCC Cross-Compiler. I want to build the ...
7
votes
1answer
5k views

How to set the CPU freq. in Linux?

I'm using this ARM9 SAM9G25 embedded system, that when switched on, is only online for a few seconds and because I want to speed up the whole process, I'd like to check the CPU frequency, and set it ...
7
votes
1answer
563 views

How can I find the Secure Attention Key (SAK) on my system and can I disable it?

In answer to My process was killed but I cannot understand the kernel notice, I was pointed to some documentation on the Secure Attention Key (SAK) on Linux. I have a embedded system generated using ...
6
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3answers
2k views

Is making /etc directory read only a bad idea?

I have an embedded system setup built using buildroot and using initramfs. It runs on compact flash device where I have created separate ext3 partitions to mount /etc/ and /var directories as well as ...
3
votes
3answers
266 views

Is CentOS PPC64 supported by Freescale T2080 RDB?

I am working on Freescale T2080 RDB. I got CentOS for PPC64 architecture from this link. I made a bootable SD card with the CentOS minimal ISO using the following command: dd bs=4M if=CentOS-7-...
2
votes
1answer
2k views

How to debug Linux hang?

We are using beagle bone black based custom board, with kernel version 3.12. We are facing system hang during one of the init script,(Which brings up WiFi) this hang happens after random number of ...
7
votes
3answers
14k views

Location of the kernel binary (when not in /boot)?

I failed to find the kernel binary in the standard location in /boot. I've also searched the whole file system for vmlinux or bzimage find / -iname vmlin* find / -iname bzimage However, this is an ...
6
votes
4answers
4k views

How do I install GCC on a system with no compiler?

I've been messing around with my NAS which runs on Linux. I have root access, but there is no compiler. I seem to remember something about being able to compile on another system, but I'm not certain. ...
6
votes
1answer
8k views

What is a “watchdog reset”?

After reading this question, I was a little confused; it sounds like some daemon reacting by rebooting a system. Is that right? Is it a common occurrence in embedded *nixes?
4
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0answers
494 views

Confusion with how to restore corrupt ext3 files if power outage occurs during a file write

I am running a small embedded system. Because the system will never be gracefully shutdown and will just have the power cable unplugged, I am running an initramfs but mounting an ext3 partition on a ...
3
votes
1answer
3k views

How to custom build debian's busybox?

I'm building an embedded system based on debian 7, and I'd like to make the most out of busybox that comes with debian. The problem is default busybox build in debian seems quite minimal, for example ...
2
votes
1answer
962 views

Good OpenWRT alternative? [duplicate]

Possible Duplicate: Open Source router firmware options? I own an ASUS wl-520gU (4 LAN, 1 WAN, WiFi, 1 USB, 4mb flash rom, 16mb ram. Broadcom BCM5354 @ 240). I am going to use it as a micro-...
2
votes
1answer
614 views

CLFS for ARMv7 neon

I am following CLFS book (GIT-20140613-arm version), and I have a issue when building GCC with armv7 and neon combination. Target info here. My host is a clean Debian 8 with gawk, build-essential, ...
2
votes
1answer
2k views

How to connect to ssh-server running on embedded linux without /etc/passwd?

After installing ssh server on my remote machine (which runs embedded Linux), I tried to connect to ssh server from host machine but it failed. This is because I could not specify user account when ...
2
votes
1answer
2k views

How to setup touch screen for X11

I am running SuSE-based embedded system with a touchscreen. The embedded application is a graphics application which uses OpenGL over X Window for graphics. We have a user-space touchscreen driver ...
2
votes
1answer
863 views

Removed USB storage device is still mounted

I'm working on a embedded linux system based on busybox. Sometimes a USB device which is physically removed from the post is still displayed in mount, df or /proc/mounts. If I reattach the device, it ...
2
votes
1answer
5k views

How enable watchdog?

I'm struggling with the watchdog timer (wdt) for a while. I can't get it working. My microcontroller is a AriaG25, based on the AT91SAM925. I have used this tutorial to compile the kernel. The ...
2
votes
1answer
3k views

lsmod returns nothing on my embedded device

I have put a vendor supplied embedded Linux installation (called X-Linux) onto a hardware device. I ran lsmod to see what modules are loaded and nothing at all is shown. Also there is no /proc/modules ...
2
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1answer
1k views

How to check my account on embedded linux without “/etc/passwd”?

On some embedded linux systems, there is no /etc/passwd file and /etc directory is not writable (which means I cannot set user account and password?). Then what is my (default) account name and ...
1
vote
1answer
1k views

Unable to get embedded device to ping anything on the network

I have an embedded device, built using buildroot, kernel version 3.6.11 running busybox. The kernel is built with completely default options. I have configured the device according to what the network ...
1
vote
1answer
1k views

`iw dev $interface scan` not working on embedded device

Running on a custom rockchip board with Ubuntu 14.04. I look at interfaces with ifconfig: ... wlan3 Link encap:Ethernet HWaddr 08:ea:40:d7:63:27 inet addr:192.168.12.1 Bcast:192....
0
votes
2answers
647 views

make: xscale_be-gcc: Command not found

I'm new to embedded and am reading 'Embedded Linux Primer' at the moment. I tried to build an xscale arm kernel: make ARCH=arm CROSS_COMPILE=xscale_be- ixp4xx_defconfig # # configuration written to ...