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 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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82 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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110 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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63 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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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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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: *** ...
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1answer
52 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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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 ...
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243 views

No filesystem could mount root, tried: jffs2

CPU: ARM Cortex A-9 This is the kernel command line that I appears in configuration menu root=mtd:jffs2 rw rootfstype=jffs2 console=ttyps0,115200 I have put three files in flash: BOOT.BIN in mtd0 ...
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422 views

While trying to open /dev/mtd2 for read/write access: Permission denied

Looks like my MTD2,and MTD3 partitions are write protected. The OS is booting from SD card on a ARM Cortex A 9 processor. root@Xilinx-ZC702-2013_3:~# mount /dev/mmcblk0p1 /mnt/ ...
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511 views

Debian and Systemd: breaking ordering cycle error

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 ...
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tty not resizing properly

I'm running an embedded poky linux (linux-yocto v3.13) on a beagleboard. However, I'm having trouble when logging in over a serial using PuTTY: the terminal does not resize at all. Usually, the ...
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Interfacing ds1337 RTC on LPC17xx

I am a newbie and I am trying to understand how to interface DS1337(RTC) on LPC17xx Board. This board uses uclinux 2.6.33. .CONFIG: CONFIG_RTC_LIB=y CONFIG_RTC_CLASS=y CONFIG_RTC_HCTOSYS=y ...
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126 views

Arch Linux iMX6 capacitive touch LCD panel

I want to create an embedded system with a 7 inch capacitive touch screen and am planning on using Arch Linux on a Varscite made Freescale iMX6 quad based SOM development kit for this purpose. What I ...
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56 views

What are the two values in < > in a device tree .dts file ?

Following is the code snippet in a device tree file: flash@0 { compatible = "n25q128"; reg = <0x0>; spi-max-frequency = <50000000>; ...
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216 views

File system that never breaks (data loss acceptable)

There're several existing topics revolving around this issue, but what I seek is slightly different. I have an sd card on an embedded Linux and it suffers from power loss. I might be able to modify ...
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Why is my embedded Linux unable to detect the sd device?

I have this ARM9 SAM9G25 embedded System, running a Linux 2.6.39 Kernel and a Busybox. I put the Images (of the bootloaders, and the linux+initramfs) on a SD so that in the end the system is booting ...
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58 views

How to determine how many bytes / hr are being written to my SD card

I have a Debian embedded Linux system that uses an SD card as the RFS. What is a reliable way to determine how many bytes / hr are being written to the SD card?
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201 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 ...
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87 views

supported 2014 distro with 2.6.x kernel

I'm cutting my teeth at putting together a Linux install for a PC104 board that supports <= kernel 2.6.x with a Disk-On-Chip. I've read up on Embedded.org and Yocto, but before I try compiling ...
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32 views

Embedded Linux Power Failure Issues

Many routers run a Linux OS and abrupt power failure can happen. Considering this - how do they handle the possibility of file system corruption caused by a power failure? If they make the system read ...
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241 views

High RX packet error count with modem - how to analyze?

I'm testing a CDMA modem on my Debian embedded Linux system. I'm doing some wgets of large files and am seeing the connection drop now and then. Looking at the ifconfig output for the PPP interface ...
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42 views

catch http requests from another process

Suppose a process, among other things, is posting https requests, for example with curl. Assuming I have root privileges, is there a way to intercept such requests and respond with an http error ...
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412 views

How to change hard disk spin-down time on my WD MyBook Live?

I have a 2TB Western Digital MyBook Live. It works quite well and provides a web-based administration interface. There is an option to either enable or disable power saving mode, which spins down the ...
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flash_erase & nandwrite seem to work, but uname -a shows the same kernel version

I've seen this question: How can I flash_erase mtd0? I have a similar problem with my mini2440. When I use flash_erase /dev/mtd2 0 0 and then nandwrite -p -N /dev/mtd2 uImage-mini2440 ...
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Why does boot from SD card with my custom kernel result in “VFS: Cannot open root device”?

I'm using an embedded board ARM9 SAM9G25. I want to boot from SD card. When I build a linux kernel with a built-in rootfs (initramfs) then it boots. I want to separate the kernel from rootfs and I ...
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311 views

Basic script in Angstrom Linux running on a Beaglebone Black

On my embedded system, I can toggle a user led with: echo > 1 sys/class/leds/beaglebone:green:usr2/value. Similarly, I can find the value of a GPIO (gpio60) (set to input), with more ...
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106 views

Having difficulties mounting a rootfs for an embedded Linux

I want my Kernel to start a squashfs rootfs for an embedded Linux. The squashfs file is on a sdcard, therefor i put these parameters on it's command line: console=ttyS0,115200 root=/dev/sdb1 rw ...
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1k views

How to extract files from uImage?

Buildroot is generating Images for an embedded device where they should run on. This is working very well. In those Images the rootfs is included. Due to some research I'd like to look into that ...
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2answers
424 views

Setup ntp client with embedded device

I need to run an NTP client on a very limited embedded device. ntpd is available but I do not see anything like rc.conf, or ntp.conf, or xntp.conf? Can someone advise on how to setup NTP? I ran ...
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Embedded Linux: Which machine directory to pick in /arch/arm?

I am just starting out with embedded Android drivers, so any help would be great. I haven't found a lot of resources online. At the moment, I am working through a tutorial on porting a driver, and ...
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63 views

How can I add a script to embedded Linux

I have a script (let's say Hello World), that I want to include to my embedded Linux. I'm using Buildroot and want to start the script in Busybox. But because I'm cross-compiling for the target I'm ...
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125 views

Change the root filesystem on an embedded system

I'm using Buildroot to generate an embedded Linux with a kernel v. 2.6.39, which in the end starts busybox. Everything works fine when building with Initramfs as "rootfs". But Initramfs isn't the best ...
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1answer
425 views

upgrade Python to 2.7.2

I have an embedded system running on Python 2.6.5 and i want it to upgrade to 2.7.2 (I have a running system with different kernel that runs 2.7.2). I have copied the binary but then it told me: ...
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1answer
428 views

Transparent Ethernet over GRE not forwarding traffic

I am running on Linux 2.6.30.9 and have been trying to setup a transparent ethernet over GRE tunnel. The network topology used is as follows: I want to bridge PC1 and PC2 using Transparent Ethernet ...
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1answer
143 views

How to build a basic embedded linux on a Qualcomm router?

Not knowing the first thing on how to build a minimal linux system on an embedded device, I'd like to get some pointers in the right direction. Generally speaking, I'd like to know what are the ...
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1answer
147 views

How to make a USB storage device undetectable in u-boot?

I need to do a test in an embedded system where I plug in the USB storage device and do "usb start" but the USB storage device is not detected. I have a working pendrive. How to make it undetectable ...
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Log files corrupted with NUL characters and text from other processes

I am running Wind River Linux 4.3 on an embedded Freescale single board computer (SBC). Output from uname -a: Linux ge101 2.6.34.10-myname-grsec-WR4.3.0.0_cgl #1 SMP PREEMPT Mon Aug 26 01:35:35 PDT ...
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GRE supported in kernel but iproute2 cant create GRE tunnel

Im trying to create IP over GRE tunnel but i get No such device: ip tunnel add gre0 mode gre remote 192.168.152.22 local 192.168.152.21 ttl 255 ioctl: No such device I have compiled GRE support in ...
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1answer
246 views

How do I load initrd into memory to be passed to kernel when using kexec?

As the MIPS port of kexec doesn't support the --initrd param, I'm looking for workarounds to imitate the feature. According to Linux/MIPS wiki, MIPS kernels support rd_start and rd_size kernel command ...
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312 views

how do I include the qcserial module in the kernel?

I need a kernel compiled, featuring the qcserial module to have support for the Huawei EM 680 model (Gobi 3000). I got kernel 3.11.6 and can find the appropriate source file in ...
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2answers
145 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 ...
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33 views

App consumes diferent %CPU if started at start-up or from prompt [closed]

I run an application in embedded system, and it needs to start at boot. However, I have a problem with it: when I execute it at boot (from rc.local script), it consumes nearly all the CPU, making the ...
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152 views

Wget download file ( do not overwrite ) auto update script

I want to write auto update script for my embedded device, which can check and download newer version of my program and extract the files on the device. The download center is hosted on remote web ...
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114 views

What is the difference between the output of TOP command and Oprofile?

In the top command one of the processes is always showing a CPU usage of 4 to 5%. But in oprofile the CPU usage is 0.004%. I do not understand this. And I also noticed that even when a process is in ...
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139 views

Which system calls could create a new process?

When executing ps command in my Linux system i see some user processes twice (different PID...). I wonder if they are new processes or threads of the same process. I know some functions in standard C ...
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What could keep a process in 'Runnable' state indefinitely?

I am developing for embedded Linux and I have found a critical bug when stability test is performed. After 1-3 days running at some points the system becomes inoperative. Kernel network stack keep ...
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30 views

Queuing disciplines are per-interface, what happen with interfaces using same device?

I have read about queuing disciplines here http://lartc.org/. I understand that for instance band 0 of pfifo policy is prioritized over band 2 within same qdisc, but what happen when i have ppp0 and ...
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48 views

Having several qdisc for each device, which is the first to process?

I have read about queuing disciplines here http://lartc.org/. Having this traffic shaping policy: .... qdisc pfifo_fast 0: dev ppp0 root bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1 qdisc ...
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optimizing Debian wheezy for an embedded board

I have Debian 7.1 on an embedded board that I just use WiFi interface, openVPN, and run a C code. The code uses UDP socket to transfer data, and do some calculations and output some signal on GPIO. ...