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 download original ramdisk file to the computer? [closed]

Linux embedded, is it possible to download original ramdisk file to the computer, to get source code? Access via SFTP. U-boot 1.2.0 Kernel command line: root=/dev/mtdblock3 ...
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2answers
58 views

How to remount as read-write a specific mount of device?

How to remount as read-write a specific mount of device? (one folder) The file is "Read-only file system", rw-r-r, so it not allow to change permissions. I need to replace that file, then change ...
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3answers
52 views

Unable to delete files as a root user using RS232 serial cross cable

I have a device(CCTV decoder) which was rebooting itself, so cant login using LAN cable. It has RS232 port only, no VGA and keybord/USB port(Embeded PC). I connected RS232 cross cable and used ...
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0answers
15 views

How to boot on a ramdisk?

I'm working on a linux embedded for a custom board with a ARM9 processor. My kernel version is : 2.6.33 I'm trying to boot on a ramdisk, kernel correctly mount the file system but failed to execute ...
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1answer
81 views

Canot remove symlinks: after reboot, symlinks re-appear

Using ssh from BusyBox, I cannot remove symlinks: after rebooting the device, symlinks re-appear. ls -la shows that symlinks have been removed, but after rebooting device they re-appear again. Those ...
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0answers
18 views

Can't access GPIOs when switching to systemd, but why?

I'm using this ARM AT91 Sam9x5ek Embedded Device, with my Linux Images made by a Buildroot. Usually my init-system is Busybox, now I changed it to systemd. Since then I can't access the GPIO anymore, ...
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0answers
29 views

How to debug random reboots, with no kernel panic, of an embedded system?

I have two aValue RPC-10W1 embedded systems that reboots by themselves after 1-2 hours. Facts: The board will reboot within a time span of 1 to 2½ hours. The issue is present on two identical ...
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1answer
56 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 ...
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1answer
44 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 ...
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1answer
52 views

How to know free disk size witout df command? [closed]

Is it possible to check free disk size in Linux without using command lines such as df? Since my host machine is embedded Linux, there are no direct command lines that show free disk size.
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49 views

Why is my swap not being activated automatically via fstab?

I've got a Linux embedded system that I'm experimenting with (the Elektor Embedded Linux Made Easy board, based on the GNUBLIN http://en.gnublin.org/index.php/GNUBLIN-Elektor). I'm using the 3.3 ...
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1answer
23 views

Late running of scripts during bootup, ending with a reboot without the login prompt

I'm making a special "installer" for an embedded system where I'd like the kernel to boot up, execute a set of things very late in the process where the peripherals have been set up and then reboot ...
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0answers
31 views

redirecting output of /dev/fb0 to /dev/fb2

I am using IMX6 Saberauto board on Linux OS. I have 2 displays primary is HDMI and secondary is LVDS. I want to run 2 applications. One QT on primary display, which I am able to do. Second ...
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0answers
79 views

Can't login using serial on ttyO0 - BeagleBone Black

I boot Beaglebone Black, connected to my desktop by serial. It was working great, until now. Beagle is booting, output shows up on the console, but at the end I can't log in. I can't type the login, ...
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0answers
33 views

How do I know from a BeagleBone Black if it is connected via USB (as a client/slave)?

BeagleBone Black has an USB port which allows the user to access it through ssh. In general, we could say that when you plug it to a PC, the PC is the USB host and the BBB is the USB client. On the ...
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1answer
51 views

What are the disadvantages of uClibc?

I try to speed up my boot sequence, and somebody recommends to use the uClibc instead of Glibc. I've built an image with it, it gets smaller and faster to boot — but at which cost? Does anyone know ...
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0answers
45 views

cross compile embedded arm

I have the android 4.2.2 code in directory /home/sghPhone2 which compiles normal with make menuconfig but I need to compile a 4.4 kernel and possibly patch it but when I download the source from ...
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2answers
81 views

tftpput in U-Boot: error: 'Access violation' (2)

I have enabled CONFIG_CMD_TFTPPUT in U-Boot, but I am not able to use it. I have set the serverip and ipaddr environment variables. When I use it as follows, it times out: u-boot# tftpput ...
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0answers
34 views

Is there a limit of GPIOs that can be used in Linux?

When it comes to use GPIOs, is there a limited number that can be used in Linux (except through the limitation of the physical availability/amount of the ports/pins) or is it theoretically possible to ...
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0answers
82 views

Unable to add serialport (nodejs module) when generating filesystem and cross-compiling tools for an ARM processor

I am using buildroot (version 2013.08.1) to generate the filesystem and cross compiling tools to implement embedded linux on a i.MX233 processor (ARM architecture). I add the serialport module by ...
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0answers
36 views

What are the two head.S files in linux source ?

In the linux source there are two different head.S files located at: arch/arm/kernel/head.S arch/arm/boot/compressed/head.S What is the puprpose of each one and what is the order of there execution ...
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9 views

WAN interface using his own queues for QoS different that the provided by Linux

My Linux embedded system have a WAN interface with the default pfifo_fast qdisc attached to it. The web interface for configuring the system let the user configure three Queues for the WAN interface ...
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1answer
92 views

Why isn't sda1 showing up in dev and how can I fix that?

I have an embedded Linux device and I was trying to copy some files to it. I plugged in a USB stick, the dmesg shows that it was recognized, but for some reason /dev/sda1 never showed up. I'm trying ...
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1answer
26 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 ...
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3answers
83 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! 3 'applications', so to speak, are required to boot a funcitonal distro of Linux: Bootloader - For embedded typically that's U-Boot, ...
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2answers
102 views

Kernel does not skip bad blocks when mounting filesystem

I am developing for an embedded Linux application using friendlyARM's micro2440. It runs on a Samsung s3c2440 ARM processor and uses squashfs in its NAND flash. Recently, some flash blocks went bad. ...
2
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1answer
116 views

How configurable is MPTCP?

I work on embedded Linux devices that usually have hard wired Ethernet as well as cell modem connections. If I were to use MPTCP would it be possible to easily configure the system to use eth0 all ...
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2answers
66 views

live dd over a mounted read-only root partiton

I'm trying to conceive a firmware update mechanism for a Linux-based embedded system without an additional initrd/initramfs/whatever. From within the running system which has a read-only mounted root ...
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0answers
34 views

Get log from kernel while loading

There is a arm/omap2-based device without ethernet, UART ports. It has usb connection with host, numeric keyaboard, LCD display. There is working U-Boot and kernel images for this. I'm trying to ...
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37 views

Interfacing with a custom camera in Linux on the beaglebone

I'm new to Linux development and need some pointers to help me get a camera (OV7670) working on a beaglebone running Debian. Using the camera capes as a guide, I've connected the camera to the GPMC ...
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30 views

Use Rsync with HTTP

Is it possible to use rsync with an HTML POST request? If so what would the rsync command look like? For example let's say using HTML5 I have this (bear with me going back to linux stuff): <form ...
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3answers
72 views

Can I achieve functionality similar to interrupts in Linux userspace?

One of functionalities I miss the most from "small embedded" in Embedded Linux is the interrupts. A signal appears on a specific pin, or other interrupt source is triggered and whatever was done ...
13
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4answers
151 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 ...
3
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1answer
394 views

Which TCP congestion control algorithm is best for low speed radio modems?

On my project we have remote Linux nodes that communicate over the Internet via very low speed CDMA cell modems. The bandwidth on these modems is about 2kbyte/second and the RTT back to the server is ...
3
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1answer
95 views

Why doesn't 'ar' work like the manpage says?

I'm trying to use 'ar' included in Debian Wheezy armel version of binutils and it doesn't seem to operate like on other systems I've encountered. Some sample output from the command-line: $ ar ...
3
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1answer
120 views

Booting using initramfs instead of uramdisk

I am working on Zynq Microzed board. It is booting perfectly with uramdisk.image.gz but I trying to boot it with initramfs.cpio. In this regard I have made following changes in header files of ...
2
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1answer
102 views

Most reliable way to check for connected client?

I have an embedded Linux OS developed from scratch using Yocto. This talks to a Windows XP/7 client. The embedded OS runs a DHCP server and gives an address to the client. The problem is that the ...
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0answers
54 views

How can I make a configuration web page for a linux appliances? Any pre made solutions available?

I am putting together a bunch of embeded linux appliances that we will be installing at a few locations. Built the whole thing from scratch using Raspbian (debian based) and Raspberry Pis. There are ...
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0answers
42 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 ...
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1answer
57 views

How to get log from u-boot without com-port

U-boot is configured to print its logs into com-port by default. There is a device I can't receive this information (without uart/com). Can I configure u-boot to store its log strings into some place ...
1
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1answer
109 views

Conntrack TCP Timeout for state stablished not working

Im using a private IP address and I want to keep alive SNAT entries in my Router (Gateway) for at least two hours (some windows apps of my network are using TCP keepalive set to 2 hours). Gateway is a ...
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99 views

using sf probe to make u-boot faster

My uboot was running slow on a ARM cortex A9 processor based Xilinx zynq chip. Xilinx forum referred me to the following to solve this issue: +From 0a212cfc2dd4e4d1595de2ca2dde3f642e5707e7 Mon ...
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1answer
116 views

How can I boot with a compressed rootfs?

My problem is: I cannot use compressed rootfs (the kernel crashes during boot) but uncompressed ones work fine. What I did: I'm using Buildroot 2013.11 to generate Images for my embedded Linux ...
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2answers
80 views

Could not mount UBIFS on SD card

I guess this is not a big problem, still I can't see what's the matter. I'm building Images for an Embedded Linux (2.6.39) ARM9 System with Buildroot 2013.11, which is booting from an SD card. I was ...
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1answer
107 views

What does this dd command do exactly?

I have the an embedded device with this SD card: [root@(none) ~]# busybox fdisk -l Disk /dev/mmcblk0: 3965 MB, 3965190144 bytes 4 heads, 16 sectors/track, 121008 cylinders Units = cylinders of 64 * ...
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1answer
60 views

WARNING: at kernel/irq/handle.c - after changing rootfs, but why?

today I changed from an image with initramfs to an image with separate kernel and rootfs. Theses images are used for an Embedded System (ARM9 SAM9G25), that is runnging with an Linux 2.6.39. During ...
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2answers
56 views

GPIO User Space App

GPIO User Space App describes user space application to test the GPIO. Another related link is Linux GPIO Driver. This would be running on a xilinx zynq board having an ARM Cortex A 9 processor. I ...
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0answers
160 views

How to cross compile linux kernel for ARM using GNU ARM toolchain? [closed]

I'm trying to cross compile latest Linux kernel 3.14 for ARM architecture. When I executed - make ARCH=arm CROSS_COMPILE=/usr/bin/arm-linux-gnueabi- The terminal gave me an error that: make: *** ...
1
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1answer
51 views

Uninstall Linux on an embedded board

I am using an embedded board, a FOX G20 V with an ATMEL AT91SAM9G20 processor. I would like to know first of all, which specific linux version I am using on this board, but also, how to remove it. ...
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88 views

Replacing default initramfs with my own

I followed this article to develop my own sample intramfs.cpio Now I have to put this in my kernel and compile. The procedure that I follw for petlinux is that I first run petalinux-config (and ...