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 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 ...
0
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1answer
584 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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1answer
116 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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1answer
660 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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1answer
118 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 or,...
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1answer
1k 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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1answer
448 views

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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3answers
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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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1answer
747 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 sys/class/...
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1answer
396 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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2answers
11k 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
4k 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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1answer
217 views

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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3answers
475 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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1answer
459 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
9k 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
1k 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 ...
2
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1answer
330 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
316 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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0answers
488 views

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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2answers
2k views

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 ...
5
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1answer
612 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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1answer
1k 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 ./drivers/usb/serial/...
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3answers
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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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1answer
364 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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0answers
262 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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1answer
1k 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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43 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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1answer
66 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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1answer
947 views

What could cause a run time remounting of my /var partition to be read only?

I have a buildroot generated embedded linux system (x-86 geode processor) using an initramfs but with /var and /etc mounted onto a compact flash device using the default mount options specified in ...
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2answers
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What does ifup do when “/etc/network/interfaces” has an invalid netmask address?

The interfaces file looks like below: auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 192.168.0.130 netmask 250.255.255.0 gateway 192.168.0.254 As you can see ...
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1answer
4k 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=...
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2answers
148 views

embedded linux and powering usb stick

I have a problem where I need to read a usb-stick or a usb keyboard: When I plug in the USB stick or keyboard I can't get power to the device. dmesg says nothing I tried: for device in $(ls /sys/...
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1answer
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ttyS1/uart1 initialised but not accessible through /dev/ttyS1

I'm not sure at which level I am having a problem. System is a LeopardBoard DM368 running TI's own SDK / LSP / BusyBox kernel, the core Linux kernel is 2.6.x so using serial_core.c driver model. By ...
2
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1answer
2k views

Know when a memory address is aligned or unaligned

Im getting kernel oops because ppp driver is trying to access to unaligned address (there is a pointer pointing to unaligned address). Im not sure about the meaning of unaligned address. It means not ...
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4answers
8k views

Linux running on SmartTV?

I recently bought a Samsung SmartTV. After setting up the wifi connection, I surfed to http://ip.comlex.de, which gave me the following information about the browser: REMOTE_ADDR: ###.###.###.### ...
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2answers
4k 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. ...
3
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1answer
2k 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 ...
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1answer
1k views

What is the easiest way to draw graphics on Linux framebuffer?

I have some embedded Linux ARM chip with LCD display on frame-buffer. I connect to chip with serial console. I can access frame-buffer directly with low-level commands. However I need to draw some ...
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1answer
1k views

mmcqd hangs and burns the CPU on the embedded device

On my embedded system I'm writing an intensive video stream to SD. I don't mount partitions, just write to /dev/mmcblk0p1. After a while my writing process hangs. I get [16952.240000] INFO: task vrec:...
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1answer
58 views

Adding access to PPP

I have a PPP connection over USB (dev ppp0), and an eth0 connection. My Linux box has IP 192.168.1.1, I have a second Windows PC with an IP of 192.168.1.3. The ppp conection is 192.168.1.2 - which is ...
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1answer
2k views

How to configure linux to output to monitor

I'm currently running a lightweight Debian distro on a development board from Compulab. I have to login to the system via serial port everytime. The system has graphical card and the driver is ...
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0answers
317 views

Compiling a simple character device driver as a module

I wrote a simple character device driver & wanted to cross-compile it for craneboard (ARM architecture). My file name is gDev.c. I copied the file to kernel/drivers/char directory in craneboard ...
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230 views

Changing Android files in root directory

Does anyone know how (if it is possible) to change Android files stored in root directory, particularly logo.rle? I want to change my boot splashscreen, changing the file, which is stored in /. I have ...
2
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1answer
2k 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 ...
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2answers
2k views

How do I send text to a USB device?

I'm trying to get the "Torobot" USB servo controller to work with Angstrom on a Beagle Board XM. The servo controller registers as a USB device. The device just takes simple text commands, but there ...
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2answers
391 views

Which embedded Linux platform supports Suspend to RAM?

I am trying to save maximum energy for a certain embedded Linux application. Currently I am using Raspberry Pi. But it looks like Raspberry Pi doesn't support Suspend to RAM. What alternative embedded ...
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1answer
2k views

Beaglebone Black Device Tree for LCD4 cape

The device tree for LCD4 cape is located at /lib/firmware/BB-BONE-LCD4-01-00A1.dts When I looked into it, the declaration of those GPIO buttons confuse me. There are five buttons according to ...
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1answer
419 views

can linux be configured to blink an LED (GPIO) on disk activity?

I'm hoping to blink an LED that is wired up to a GPIO line whenever the USB connected disk has activity is there an easy way to pull this off?
3
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1answer
409 views

Is it possible to have two seperate one way (simplex) serial ports to make single tty device?

I am building embeded device, which has IR comunication with PC and it will have two IR Led/detector pairs which are one-way and are setup like this: IR source input commands -> near embeded device ...