date int64 1,220B 1,719B | question_description stringlengths 28 29.9k | accepted_answer stringlengths 12 26.4k | question_title stringlengths 14 159 |
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Will it be legal if I use the DuckDuckGo search engine without Creating a DuckDuckGo Email Protection account?
Or
Can I use the DuckDuckGo search engine without Creating a DuckDuckGo Email Protection account?
Thank you
| ERROR: type should be string, got "\nhttps://duckduckgo.com/ is a completely free of charge search engine. What's more, there is absolutely no obligation or reason to register. Just go to the web site and search without the need of registration or anything related.\n" | Can I use the DuckDuckGo search engine without Creating a DuckDuckGo Email Protection account? [closed] |
1,312,470,873,000 |
Possible Duplicate:
“No such file or directory” lies on Optware installed binaries
I'm trying to add ebtables to a little router box. I went and got a binary compiled for the correct architecture, and put it on the box in /sbin/. When I do /sbin/ebtables, the shell says /bin/sh: /sbin/ebtables: not found, but I ca... |
It could be a missing dependency. Notably you'll get that type of message if the runtime linker ("program interpreter") set in the ELF header does not exist on your system.
To check for that, run:
readelf -l your_executable|grep "program interpreter"
If what it gives you does not exist on your system, or has missing ... | Why does sh say "not found" when it's definitely there? [duplicate] |
1,312,470,873,000 |
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-updating webpage from the data-collection server) failed to boot due to filesystem corruption. Ext4, Manual fsck required, the... |
The best resistance against corruption on a single SD card would be offered by BTRFS in RAID1 mode with automatic scrub run every predefined period of time.
The benefits:
retaining ability to RW to the filesystem
modern, fully featured filesystem with very useful options for an RPi, like transparent compression and s... | Corruption-proof SD card filesystem for embedded Linux? |
1,312,470,873,000 |
I am looking for a way to mount a ZIP archive as a filesystem so that I can transparently access files within the archive. I only need read access -- the ZIP will not be modified. RAM consumption is important since this is for a (resource constrained) embedded system. What are the available options?
|
fuse-zip is an option and claims to be faster than the competition.
# fuse-zip -r archivetest.zip /mnt
archivemount is another:
# archivemount -o readonly archivetest.zip /mnt
Both will probably need to open the whole archive, therefore won't be particularly quick. Have you considered extracting the ZIP to a HDD o... | Mount zip file as a read-only filesystem |
1,312,470,873,000 |
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.)
I have access to the /etc/shadow file itself.
|
You can easily extract the encrypted password with awk. You then need to extract the prefix $algorithm$salt$ (assuming that this system isn't using the traditional DES, which is strongly deprecated because it can be brute-forced these days).
correct=$(</etc/shadow awk -v user=bob -F : 'user == $1 {print $2}')
prefix=$... | How to check password with Linux? |
1,312,470,873,000 |
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 generated file (e.g. different compression modes set by the Buildroot were applied and now shall be checked if they were corr... |
mkimage -l uImage
Will dump the information in the header.
tail -c+65 < uImage > out
Will get the content.
tail -c+65 < uImage | gunzip > out
will get it uncompressed if it was gzip-compressed.
If that was an initramfs, you can do cpio -t < out or pax < out to list the content.
If it's a ramdisk image, you can try... | How to extract files from uImage? |
1,312,470,873,000 |
When booting a kernel in an embedded device, you need to supply a device tree to the Linux kernel, while booting a kernel on a regular x86 pc doesn't require a device tree -- why?
As I understand, on an x86 pc the kernel "probes" for hardware (correct me if I'm wrong), so why can't the kernel probe for hardware in and... |
Peripherals are connected to the main processor via a bus. Some bus protocols support enumeration (also called discovery), i.e. the main processor can ask “what devices are connected to this bus?” and the devices reply with some information about their type, manufacturer, model and configuration in a standardized form... | Why do embedded systems need device tree while pcs don't? |
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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" is a specification/standard for adding devices to an (embedded) Linux kernel.
|
The device tree is exposed as a hierarchy of directories and files in /proc. You can cat the files, eg:
find /proc/device-tree/ -type f -exec head {} + | less
Beware, most file content ends with a null char, and some may contain other non-printing characters.
| How to list the kernel Device Tree [duplicate] |
1,312,470,873,000 |
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 inside the CPU gets interrupted, and my function of interrupt handler is launched. In Linux everything is buffered, if somet... |
If I understand your question this articled sounds like what you're looking for. The article is titled: Device drivers in user space.
excerpt
UIO drivers
Linux provides a standard UIO (User I/O) framework for developing user-space-based device drivers. The UIO framework defines a small kernel-space component that per... | Can I achieve functionality similar to interrupts in Linux userspace? |
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I have an embedded Linux ARM system that is showing significantly less throughput than expected on both Ethernet and USB. I suspect the memory may be contributing. Is there a way to observe the memory bandwidth that is consumed while running a throughput test on the Ethernet or USB?
|
There is a memory bandwidth benchmark available in open source. It works for Intel & ARM under Linux or Windows Mobile CE.
It will give you raw performance for your memory as well as system performance with memory. But it won't give you a real-time bandwidth, so I don't know if it's a good answer to your question.
Th... | How can I observe memory bandwidth? |
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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 built-in and it already works with
root=/dev/mtdblock2 rootfstype=squashfs
for booting from the flash.
EDIT: This is a... |
I would use an initramfs. (http://www.kernel.org/doc/Documentation/filesystems/ramfs-rootfs-initramfs.txt)
Many Linux distributions use an initramfs (not to be confused with an initrd, they are different) during the boot process, mostly to be able to start userspace programs very early in the boot process. However, yo... | How do I have Linux boot with a rootfs in RAM? |
1,312,470,873,000 |
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 U-Boot, although not a hard requirement.
Kernel - That's pretty straightforward.
Root Filesystem - Can't boot to a shel... |
That entirely depends on what services you want to have on your device.
Programs
You can make Linux boot directly into a shell. It isn't very useful in production — who'd just want to have a shell sitting there — but it's useful as an intervention mechanism when you have an interactive bootloader: pass init=/bin/sh to... | What are the minimum root filesystem applications that are required to fully boot linux? |
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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 create the kernel image and cross compilation tools. I have partitioned the CF device into a small FAT partition where t... |
New answer (2015-03-22)
(Note: This answer is simpler than previous, but not more secure. My first answer is stronger because you could keep files read-only by fs mount options before permission flags. So forcing to write a files without permission to write won't work at all.)
Yes, under Debian, there is a package: fs... | Is using a read only root file system a good idea for embedded setup? |
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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. If we go with a simple GPIO button array, I can easily write program that will look for keypresses on those GPIO lines. ... |
Devices most likely get a file in /dev/input/ named eventN where N is the various devices like mouse, keyboard, jack, power-buttons etc.
ls -l /dev/input/by-{path,id}/
should give you a hint.
Also look at:
cat /proc/bus/input/devices
Where Sysfs value is path under /sys.
You can test by e.g.
cat /dev/input/event2 ... | Is it possible for a daemon (i.e. background) process to look for key-presses from a USB keyboard? |
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This question is fairly lengthy, so I'll ask the questions at the top and then go through my method of coming to the questions:
Did (Busybox based) rm not execute because there wasn't enough contiguous RAM?
If so, is there a lightweight method of defragging the DMA - without resorting to a system restart?
If not, wha... |
It's taken a bit of time, but I thought I'd hold off answering until I had answers to all 3 of my sub-questions.
Before I start though, I will mention that the correct term when it comes to "de-fragmenting" working memory is referred to "compacting" working memory.
1. Did rm not execute because there wasn't enough con... | Defragging RAM / OOM failure |
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I'm dealing with an embedded device running Linux. The manufacturers of this device have it set up so that it loads the root filesystem as readonly.
From /etc/mtab:
rootfs / rootfs rw 0 0
/dev/root / squashfs ro,relatime 0 0
This means that I'm unable to modify any files within /etc, such as to add a new user.
I've t... |
squashfs is a read-only compressed file system. It has no provision to make modification to it once it's been created. So you couldn't write to it even if the underlying block device could be made writeable. You'd need to create a new squashfs image of the whole filesystem with your modifications and burn it to the st... | Make readonly /etc writeable |
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I'm trying to identify an embedded Linux distribution. Here are the commands I have typed so far:
$ uname -a
Linux LIN-SRV-EMB01 3.10.105 #25556 SMP Sat Aug 28 02:14:22 CST 2021 x86_64 GNU/Linux synology_bromolow_rs3412rpxs
$ lsb_release
-sh: lsb_release: command not found
$ ls /usr/lib/os-release
ls: cannot access ... |
The uname -a output identifies this as a Synology device. Such devices run Synology DiskStation Manager. This is Linux-based, but it is not managed like a typical Linux system running a “traditional” Linux distribution. It has its own package manager, synopkg, for which third-party packages are made available by SynoC... | How can I identify an embedded Linux distribution? |
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How to know whether a particular patch is applied to the kernel? Especially RT-Preempt Patch.
|
In the case of preempt you can just use uname:
uname -v
#23 SMP PREEMPT RT Fri Oct 16 11:52:29 CET 2012
The string PREEMPT shows that you use a kernel version with the realtime patch.
Some other patches might also changes the uname string. So it might also be a help. If this is not the case you can try to look at you... | Checking linux Kernel for RT-Preempt Patch |
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I'm currently trying to make HSP bluetooth profile works on a custom board based on Atmel SAMA5D2. I'm using a custom Linux made from Buildroot-2017-08.
I'm at the point where I try to configure pulseaudio. The pulseaudio package is the one from buildroot and I ticked "start as system daemon".
When the system starts, ... |
Finally, seems that it was a profile issue.
I just changed the umask line from umask 077 to umask 007 in /etc/init.d/S50pulseaudio so members of group pulse can access files.
Content of /etc/init.d/S50pulseaudio:
#!/bin/sh
#
# Starts pulseaudio.
#
start() {
printf "Starting pulseaudio: "
#umask 077
... | Pulseaudio daemon not running for pacmd |
1,312,470,873,000 |
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, a shell, basic perl and a ftp server. There are some distributions for embedded systems which can do this, however I h... |
After quite some research I settled in the end for SliTaz. I can really recommend it, as I haven't found any distribution which is so flexible. There is a minimum system (well under 20 MB--choose from the Live CD flavors), basically giving you just a shell and ssh access. However, there is a huge package repository so... | Which minimal but extendable Linux distribution to choose |
1,312,470,873,000 |
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 using to store persistent measurement logging data created by a custom written c++ application. I chose the ext3 file syste... |
As with all things pertaining to security, there aren't any guarantees, but you also need to balance risk (and cost) against probability. From experience (and I've been running dozens of *nix boxen since the dark ages), I've never really had significant power-caused filesystem corruption.
Some of these machines were e... | What filesystem offers best protection for securing data against corruption due to power loss? |
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I'm looking for a programmable Linux controller for home automation and general fun projects.
Requirements:
Controlling electric appliances - On/Off switches and dimmers (perhaps using relays)
Receive analogue and digital data from sensors (switches, temperatures, etc.)
USB connection
Running Linux
Advantages:
Netw... |
Is not so powerfull as a normal PC, but you should try arduino platform.
You can buy a great and cheap unit here: http://www.libelium.com/
Google a little bit about arduino and you will find a lot of references and a big community
| Linux Programmable Controller |
1,312,470,873,000 |
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 file with dd.
Then I use parted to set up the partitions.
I mount them each in a loop device then format them; ext2 for '... |
Firstly, writing a sparse image to a disk will not result in anything but the whole of the size of that image file - holes and all - covering the disk. This is because handling of sparse files is a quality of the filesystem - and a raw device (such as the one to which you write the image) has no such thing yet. A spar... | How do I create small disk image with large partitions |
1,312,470,873,000 |
Can the default permissions and ownership of /sys/class/gpio/ files be set, e.g. by configuring udev? The point would be to have a real gid for processes that can access GPIO pins on a board.
Most "solutions" include suid wrappers, scripts with chown and trusted middleman binaries. Web searches turn up failed attempts... |
The GPIO interface seems to be built for system (uid root) use only and doesn't have the features a /dev interface would for user processes. This includes creation permissions.
In order to allow user processes (including daemons and other system services) access, the permissions need to be granted by a root process at... | Set GPIO permissions cleanly |
1,312,470,873,000 |
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 embedded device not a standard desktop. Is it possible that the kernel binary is located on a different storage location ... |
/boot is the standard location for the kernel in desktop/server distributions, but embedded systems vary greatly. Where the kernel is stored entirely depends on your bootloader, and it may not be a file as embedded bootloaders are often not capable of reading Linux filesystems.
For example, with U-Boot (a popular embe... | Location of the kernel binary (when not in /boot)? |
1,312,470,873,000 |
I am working on an embedded device running on Linux.
This device communicates with a server and sends data to it using a certificate and a private key.
When we distribute the device, I am afraid that some evil people might steal that private key by hacking through the file system of the embedded device, and try to tam... |
If your hardware is not physically secure, nothing you do in software will give you physical security.
Don't bother encrypting unless you have a separate, secure location for the key. Full disk encryption on a computer is useful when someone types in the (password to derive the) key at boot time. Full disk encryption ... | Encrypt files (private key, etc.) in an embedded system |
1,312,470,873,000 |
The system clock is maintained by the kernel, whereas the hardware clock is maintained by the Real Time Clock (RTC).
Do both clock run at same frequency?
Are both independent of each other?
What happens when Real time clock fails? Does it affect the system clock?
Can anyone let me know the difference between both th... |
both clock run at same frequency?
Usually there are two clocks inside a computer/device/system. One is powered from a battery (usually a CR2032, could be the main battery or even a supercap in an embedded system) and runs from an dedicated chip. The other one is driven by the CPU clock source (with its own quartz cry... | System Clock vs. Hardware Clock (RTC) in embedded systems |
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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 buildroot which uses busybox and the busybox init system. I am unable to find either rc.local or rc.sysinit on my system... |
According to this mailing list post SAK is «break», k. So you could be receiving it over the serial port. The kernel sysrq documentation agrees.
That kernel document also gives a solution: disable sysrq by echo 0 >/proc/sys/kernel/sysrq. Or, alternatively, only enable the ones you'd like.
You can also configure SAK us... | How can I find the Secure Attention Key (SAK) on my system and can I disable it? |
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I have compiled and installed the 2.6 kernel on an ARM board. I am using the ARM mini2440 board.
I would like to know if there is already a way to access the General Purpose I/O port pins?
Or will I have to do ioctl() and access them directly from the memory?
|
Use the sysfs control files in /sys/class/gpio. The following links will hopefully be useful to helping you get started:
http://www.avrfreaks.net/wiki/index.php/Documentation:Linux/GPIO
Have seen reports of this article on the Beagle Board also working with the mini2440:
http://blog.makezine.com/archive/2009/02/blink... | Linux kernel 2.6 on ARM |
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Is there a command like
vi > out
vi | out
That I could use to cause a watchdog reset of my embedded linux device?
|
If you have a watchdog on your system and a driver that uses /dev/watchdog, all you have to do is kill the process that is feeding it; if there is no such process, then you can touch /dev/watchdog once to turn it on, and if you don't touch it again, it will reset.
You also might be interested in resetting the device u... | How do I cause a watchdog reset of my embedded Linux device |
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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.
root@LSB1:~# uname -a
Linux LSB1 2.6.22.18-88f6281 #50 Tue Dec 22 18:06:23 JST 2009 armv5tejl unknown
|
Cross-compiling may be the solution for you It allows you to compile executables for one architecture on a system of a different architecture. Here's an introduction
| How do I install GCC on a system with no compiler? |
1,316,828,411,000 |
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 custom directory to store data. I am not entirely certain if this is a good idea or not, but I need access to sytem log... |
A read-only /etc is increasingly common on embedded devices. A rarely-changing /etc is also increasingly common on desktop and server installations, with files like /etc/mtab and /etc/resolv.conf located on another filesystem and symbolically linked in /etc (so that files in /etc need to be modified when installing so... | Is making /etc directory read only a bad idea? |
1,316,828,411,000 |
I have a small custom embedded Linux distribution (created with OpenEmbedded), which boots with GRUB 1.99. The aim is to have it start up fast.
Currently it says:
GRUB loading.
for ~2+ seconds (this is probably unavoidable). Then:
Welcome to GRUB!
under it for a fraction of a second when it has finished loading.
(Th... |
I didn't find the cause of the slow booting with GRUB 2.
I ended up using EXTLINUX instead, which is compact and fast, and better-suited if you don't need all the fancy GRUB 2 things.
http://www.syslinux.org/wiki/index.php/EXTLINUX
| Why is GRUB 2 booting so slowly? |
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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?
|
Having a watchdog on an embedded system will dramatically improve the availability of the device. Instead of waiting for the user to see that the device is frozen or broken, it will reset if the software fails to update at some interval. Some examples:
Linux System http://linux.die.net/man/8/watchdog
VxWorks (RTOS)... | What is a "watchdog reset"? |
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Anyone know what happens when UBI uses up all its reserved PEBs that are reserved for bad block management? For example say I have a UBI volume that has 14 PEBs reserved
# ubinfo -d 1
ubi1
Volumes count: 1
Logical eraseblock size: 126976 bytes, 124.0 KiB
Total amount of logi... |
I've tested it on armv5tel GNU/Linux 2.6.39+ by marking physical eraseblocks (PEB) as bad using the U-Boot command line:
When the bad PEB count is higher than the amount of reserved PEBs, the volume will still be usable. As long as free blocks are available they are used to replace the bad ones. Problems will occur wh... | UBI bad block management |
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I recently tried to install OpenBSD to my Soekris net4526, but the 64MB onboard storage is too small. Is there any way to make OpenBSD smaller, because even the smallest configuration (bsd and baseXX.tgz only) doesn't fit.I tried with OpenBSD 3.9. Can you give me some links?
|
The good news is it can be done, but you'll need to know what you're doing and you won't be able to ask for any help on the openbsd mailing lists.
You'll need:
a more powerful build machine then your soekris
a list of things to delete which will be based on whatever compromises you're willing to make. (You haven't gi... | OpenBSD - Reduce the Base Install Size for Smaller Systems |
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I'm in a situation where I have a 10/100/1000-capable PHY cabled only to support 10/100.
The default behaviour is to use the autonegociation to find the best mode.
At the other end, using a gigabit capable router ends in a non-working interface. I guess autonegociation never converges.
I've heard some people tried wit... |
The thing with autonegotiation is that if you turn it off from one end, the other side can detect the speed but not the duplex mode, which defaults to half. Then you get a duplex mismatch, which is almost the same as the link not working. So if you disable autonegotiation on one end, you practically have to disable it... | Remove SOME advertised link modes with ethtool |
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I have used buildroot to successfully create a kernel, root file system and cross-compilers to enable me to write application code to run on an embedded device. Currently I have no need to write device drivers and currently have no idea how to go about it anyway but it is quite likely that in future I may need to do t... |
3.x is just continuation of 2.x - at one point Linus decided that the "x" part of the version is too big. Generally you probably want reasonably recent kernel, probably one marked as "longterm". A lot also depends on your application as well - while remote security holes in kernel are rather scarce, local problems are... | What considerations need to be made when choosing the version of kernel for an embedded device? |
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I've worked with a few embedded systems, but now I'd like to make my own piece of hardware and despite a pretty thorough knowledge of Linux, I have no idea how to get Linux up and running on new hardware. So I'm looking for resources on how to do some board bringup/support.
Some more details:
I'm wondering about the f... |
I worked on a system using uboot which had custom hardware and was ported to arm and powerpc. There were two things that needed to be set up. First there is a place in u-boot where you can add board support to set registers and create handler functions for accessing RAM or FLASH on your device.
You then have to write ... | Resources for very low-level (board bring-up) |
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In this question over at superuser several answers report SDHC card failures in Raspberry Pi single-board computers and other embedded devices over the course of periods varying from weeks to years.
In comments to this answer to an unrelated question about the swappiness, there was speculation as to whether adjusting... |
The answer to this depends heavily on your use case.
I no longer own a Raspberry Pi,
but the one I used to have came with 512 MB of RAM.
Conveniently, my NFS server has the same amount.
In addition to NFS, this server (like all my others)
has an m68k cross-compiler that sees regular use via distcc.
It also has an alwa... | How does swappiness affect the longevity of SDHC memory cards in embedded computers? |
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I have just learned of Gentoo's sys-devel/crossdev package. This is a package that is useful for creating a cross-compiling toolchain.
Are there any other such packages out there on other distributions?
I'm specifically interested in distro-maintained packages because I've tried a couple of others (buildroot, crosstoo... |
On Debian, there are apt-cross and dpkg-cross from Emdebian, which let you set up cross-compilation for many architectures (you get cross-compilers and libraries).
On Ubuntu, there's a crosschain for ARM, and a project to improve on this.
You can also create toolchain using crosstool-ng which is not link to a distribu... | What distribution-maintained cross-compile toolchain packages exist? |
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I'm wondering if it's possible to make a Linux system appear like an USB peripheral.
Like smartphones which can switch from master to slave depending on the device they are connected to, I would like to know if it's possible to have the same behavior with a Linux system.
For example, I have an embedded Linux on a card... |
Yes, you can, but it is not easy. You need at least a little work with it.
Working as an USB slave is supported in Linux since around the 2.4 or 2.6 times. You have to find a compatible chip, then a device having it, and then buying one, somewhere (typically, to rent it on the Internet).
Specifically for USB gadgets, ... | Configure Linux system as an OTG device |
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On an mtd partition with 39 erase blocks (= 4.9 MiB), I tried to format a ubifs. The resulting file system has free space of 2.2M uncompressed data when reserved blocks are reduced to the minimum possible 1 block (I know that's not good). This means that only 45% of the space is usable for data.
The same area formatt... |
Why the numbers don't match up
The "at least 17 erase blocks" warning counts blocks needed by the UBIFS filesystem itself. Of those 17 erase blocks, 14 are UBIFS overhead and 3 are usable filesystem space. The underlying UBI layer underneath also uses 5 erase blocks of overhead.
Getting More Space
There's no way to ... | Surprisingly big overhead when creating small ubifs volume |
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I am attempting to boot the freescale 1040RDB and am having some difficulty. I'm using a pre-built SDK from Freescale that has a linux VB image with the yocto installation along with all of the yocto layers and configurations pre installed. I've been able to successfully run bitbake and am now trying to deploy the ima... |
This seems like the memory at which fdt is getting corrupted (usually due to overwrite) when kernel image starts to un-compress. Try loading fdt at a higher address e.g. 0xe00000.
| ERROR: image is not a fdt - must RESET the board to recover |
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I am working on a embedded Linux with u-boot as bootloader and systemd init system. The tools are limited to standard busybox.
While analyzing some problems, I figured out the root filesystem is read only which causes the problem. The reason is some of the services and programs depend on a writable root fs, causing ma... |
At boot, you are supposed to check your filesystems to see if the system was shut down properly or if it crashed, and perform the necessary recovery actions in the latter case. On modern journaled filesystems, this usually means a simple and quick journal recovery operation that can be done automatically.
Root filesys... | When can Linux boot with a Read-Only Root Filesystem |
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It seems that I have a lack of understanding how booting SD-Card images on devices like the Banana Pi work. The situation is as follows.
I have a Banana Pi and a Banana Pro. Every device has an image of some distribution on a SD card plugged into the device (Banana Pro -> Arch Linux, Banana Pi -> Bananian). The image... |
I think you've missed bootloader. U-Boot has to be present on your SD. Take a look at how the SD layout should be for the Banana Pi / Pro:
http://wiki.lemaker.org/BananaPro/Pi:Setting_up_the_bootable_SD_card#SD_Card_Layout
| How to create boot SD card for Banana Pi manually |
1,316,828,411,000 |
I am trying to develop an application to run on an embedded linux installation. It comes with an older version of libc than I have on my development maching. If I were to create a chroot environment on my development machine, copy the libraries from my embedded device in such a way that the chroot environment mirrors ... |
This will generally work. I would just give it a try, but there are a few things you need to be aware of:
When building, binaries need to be built for the CPU architecture and capabilities of your target. Given that they're both x86, this will help a lot, but you still need to be careful about using processor feature... | Can I use a chroot on my dev machine to build an application to run on embedded linux installation? |
1,316,828,411,000 |
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 EEPROM (electrically erasable PROM) and is accessible via the I²C bus at address 0x50.[1] The EDID PROM can often be read... |
Answer to my own Question: [:)]
i2cdetect -l : To enlist the existing i2c adapter
echo Y | i2cdump $i 0x50 : Where i is the device id of each /dev/i2c-*
The above command will print the Raw-EDID for the given I2C-Adapter.
Now custom C ( or any ) programming language can be used to parse the information to give... | Reading EDID from EEPROM |
1,316,828,411,000 |
I have an Atmel SAM9X system running Angstrom. I am trying to make a recovery partition so when a user holds a button during boot up the recovery partition boots up.
I have modified the bootstrap so when a button is held on boot up, an alternate linux kernel is loaded. What I want is the alternate kernel to load linu... |
The kernel contains a default root partition setting, determined at compile time (you can change it in the binary image with the rdev command). You can pass an argument on the kernel command line to override this default at boot time, e.g. root=/dev/mmcblk9p42 to boot from MMC device 9 partition 42 instead of the defa... | Making a recovery partition in embedded Linux |
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Looking for an inexpensive embedded device that contains 2 Ethernet Ports, runs Linux (or some other type of Unix), and is under $50.
My main concern is cost. It must be under $50 and have 2 Ethernet ports.
It can be a bare circuit board, it doesn't need to be a complete device with cover and all.
|
http://soekris.com/
Not at the $50 level, but probably what you're looking for in general.
| Low Cost, 2 Ethernet Ports & Runs Linux [closed] |
1,316,828,411,000 |
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 u-boot:
zynq_common.h and zynq_common.h.save changes are as follows
"ramdisk_image=uramdisk.image.gz\0"
to
"ramdisk_image=i... |
I think you should convert it to u-boot file like this and give it a try:
mkimage -n 'Ramdisk Image' -A arm -O linux -T ramdisk -C gzip -d initramfs.cpio.gz initramfs.uImage
This might be a valid format for u-boot.
| Booting using initramfs instead of uramdisk |
1,316,828,411,000 |
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 have to move it to the ext4 partition of eMMC. File nothing but a certificate
in some situations, we have multiple certs in... |
Is moving file from tmpfs to ext4 atomic?
No. Renames as such only work within a filesystem. The manual page for rename(2) explicitly mentions the error that is returned if trying to rename across mount points:
EXDEV oldpath and newpath are not on the same mounted filesystem.
Moves across file systems need to be d... | is there a way to atomically move file and directory from tempfs to ext4 partition on eMMC |
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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 directory on the system. What does this mean? Does it mean that no drivers are loaded to communicate with the rest of ... |
This just means that the drivers are compiled directly into the kernel and that the kernel does not have module support. If you know exactly your target system and the purpose you don't necessarily need module support.
| lsmod returns nothing on my embedded device |
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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 in a failure to mount the NFS share. However, I know that the ethernet hardware works, because U-boot loads the kernel v... |
You can compile a initrd image into kernel (General Setup -> Initial RAM filesystem and RAM disk (initramfs/initrd) support -> Initramfs source file(s)). You specify file in special format like (my init for x86):
dir /bin 0755 0 0
file /bin/busybox /bin/busy... | Debugging ethernet before NFS boot |
1,470,727,670,000 |
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 library that could create a new process such fork(). I wonder what concrete functions can make a process appear twice w... |
Little bit confusing. fork is a system call which creates a new process by copying the parent process' image. After that if child process wants to be another program, it calls some of the exec family system calls, such as execl. If you for example want to run ls in shell, shell forks new child process which then calls... | Which system calls could create a new process? |
1,470,727,670,000 |
I have compared this in different systems, but only get this behavior in an embedded system running Arago linux.
I use the date command from BusyBox v.1.13.2
I executed this two commands "simultaneously":
[root@host:~] date; date -u
Fri Mar 18 12:56:49 CET 2016
Fri Mar 18 11:57:14 UTC 2016
The output of zdump is as e... |
By following the strace of the first command (date):
open("/etc/localtime", O_RDONLY)
It access the timezone file pointed by /etc/localtime which is /usr/share/zoneinfo/europe/Zurich in my case. So everything fine so far.
The strace of the second command (date -u) gave me hints why it wasn't working properly:
open... | UTC vs. localtime has an offset of about 25 seconds |
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On my Beaglebone Black I added a I2C real-time-clock to not being reliant on ntpd to maintain accurate timing. The outcome is that there are two special device files in /dev. These are /dev/rtc0 and /dev/rtc1 but there is also /dev/rtc which is a symlink to /dev/rtc0.
/dev/rtc0 is the real-time-clock within the ARM ... |
That udev rule hint pointed me in the right direction. After a quick review of writing udev rules I did the following.
udevadm info -a -p /sys/class/rtc/rtc1
The output (shortened) revealed some useful properties to define a udev rule.
looking at device '/devices/platform/ocp/4802a000.i2c/i2c-1/1-0068/rtc/rtc1':
KERN... | How can the link target of /dev/rtc be changed? |
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A program (which needs to read and write from and to the filesystem), has the extra feature of being able to communicate with an external sensor. Therefore it has the unique ability to know if a power loss is imminent. The warning I get is only a few (around 3 to 5) seconds - not enough to perform a full shut-down. A ... |
The main thing you need to do is issue a sync system call. There's a sync utility that does just that. When the sync system call returns, it guarantees that any filesystem write operation (on any mounted filesystem) that was issued before the sync is completed.
It's up to your application design to ensure that if this... | If my program detects that a power loss will occur in a few seconds, what can it do to avoid data corruption? |
1,470,727,670,000 |
I have 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 * 512 = 32768 bytes
Device Boot Start End Blocks Id System
/dev/mmcblk0p1 305 84... |
I am guessing here, as I have no Kobo Glo (I wish my Bookeen HD was reprogrammable).
You seem to have a 2Gb SD memory internally ( 60352 cylinders of 32K each)
The dd does skip 2048 blocks of 512 (1048576), which is less than the 305 cylinder offset (9994240). In fact have to write more than 8Mb to reach the /dev/mmcb... | What does this dd command do exactly? |
1,470,727,670,000 |
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 the instructions read:
copy the platform data initialization files, “driver_sources/platform.c" and "driver_sources/plat... |
According to elinux.org this should be mach-msm folder. It is a folder for Qualcomm SoCs.
| Embedded Linux: Which machine directory to pick in /arch/arm? |
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I have a router that provides internet connection to a single client device via a wireless cellular data network. This network provides non-public IP addresses which gets natted. I would like to get a static IP address outside of the network that will route everything back to the device on the cell network.
Because th... |
The only NAT that an IPIP tunnel might work with is one-to-one NAT, which is clearly not what you have in the cellular case.
This "150 bytes/second for an open SSH connection" business is very strange and you should investigate. No such thing happens for me with OpenSSH -> OpenSSH sessions (there's the unavoidable kee... | Tunnel through a NAT |
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I am working on a Colibri module having Angstrom linux installed in it! The processor is ARM v7. I am having trouble updating the softwares installed in the system.
Whenever I tried the command opkg update, I'd get a bunch of errors. Probably, it seems that the support from Angstrom project has been withdrawn as it gi... |
Sorry I just saw your question now, and I had to deal with the same issue on Apalis T30. Toradex is quite helpful if you ask them questions, but I found the solution myself in their release notes.
Newer images of Toradex builds for Apalis and Colibri have an issue with the Angstrom package feeds. (V2.3 Beta1+ is my u... | Trouble with opkg package manager in Angstrom embedded linux on Colibri module ARM v7 processor |
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I want to run SSH on Qtopia (on my FriendlyARM). My own distribution is Ubuntu, so I cannot copy and paste the ssh binary file into the device.
If I can copy and paste a binary file, where can I find it? If I must compile SSH, how is it possible in my ubuntu?
|
Your device has an ARM processor. Your PC has an x86 processor. ARM and x86 are different processor architectures with different instruction sets. An executable program compiled for x86 consists of x86 instructions that an ARM processor cannot execute, and vice versa.
You need an ARM binary. Furthermore, you need an A... | Adding ssh on embedded linux |
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I'm working on a Davinci DSP ARM embedded board. The board itself is the Texas Instruments 816X/389X EVM. I'm currently trying to get apache working on the board. The problem is that the SDK for the board is extremely basic and doesn't include 'make' or any update manager like RPM, yum, or apt-get. So I'm having a har... |
When you are compiling something for another system, it needs to be cross-compiled to that architecture. Most likely your host is an x86. The TI is an ARM. The instruction set isn't the same. You need to setup a cross toolchain to compile apache with an ARM version of g++. TI should have included cross tools with the ... | Embedded board with apache |
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The following is contained in the vendor user manual for its embedded Linux distro on the hardward board they supply
Developers can put their program onto X-Linux device via FTP or NFS.
Before running it, use ldd command on development workstation to check
dependency files. Also put relative files onto X-Linux to... |
You can copy libraries to your embedded device provided that it's running the same operating system on the same processor architecture family. Your device has an x86 processor, which is the same family as 32-bit PCs. So if you have a 32-bit Linux system on your desktop machine, you can copy libraries and executables f... | Is it safe to just copy shared libraries onto embedded Linux device? |
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My main question is how the open source community reverse engineers windows drivers (for say, video cards) to re-write them under linux.
I'm an EE graduate, so I've taken courses in microprocessor design and such, assembly, C for embedded systems, and I've worked on embedded linux. But I feel like I'm missing somethin... |
There are of course a lot of possibilities.
For example if it is an USB device you could monitor the USB traffic between the device/compute on a system with driver support (analogous to tcpdump for network). For example for Windows there are several USB monitor tools available (IIRC usbsnoop for example).
In the case ... | Capturing OS/hardware communication / reverse engineering drivers |
1,470,727,670,000 |
I am able to telnet into a router that's running a customized linux firmware. It was compiled using 'buildroot'.
I was able to dig out some specs of the router. I intend to clone the router's firmware for further study. 'dd' is not available so I tried using cat to throw the entire contents of the flash drive (mtdbloc... |
Turns out the 'cloning' step was not the problem. My router vendor had used non-standard 'magic number' to create the squashfs system. I was advised to give sasquatch a shot. Fortunately, sasquatch correctly read and understood the file compression and other details, which unsquash didn't report correctly.
Result: I h... | Clone a block device using 'cat' |
1,470,727,670,000 |
I'm running an Linux Image (kernel 3.2.8) for beagleboard-xm on QEMU's 1.4.0 emulator Ubuntu distribution for 13.04. My image is created using Buildroot beagle_defconfig. I added some pkgs to be able to debug a little.
QEMU call cmd:
`$ sudo qemu-system-arm -M beaglexm -m 1024 -sd ./test.img -clock unix -serial stdio ... |
I found what my problem was, QEMU ins't mapping the serial chardev of any extra -serial pty.
After doing the this Invoke command:
sudo qemu-system-arm -M beaglexm -m 1024 -sd ./test.img -clonix -serial stdio -device usb-mouse -device usb-kbd -serial pty -serial pty -monitor pty
char device redirected to /dev/pts/5 (la... | ttyO ports do not have the good port address on QEMU 1.4.0 running image for beagleboard-xm |
1,470,727,670,000 |
We have custom hardware running 3.2 Angstrom on a SAM9G45 processor. Everything works fine. Recently we designed similar hardware that uses the SAM9G25 processor. We found the 2.6 kernel works fine on the SAM9G25, but we needed to port the 3.2 kernel to the platform to take advatage of some wireless drivers. We comple... |
Try booting the system with the kernel-option clocksource=jiffies or nohpet.
I have an open case about SLES11 SP2 (using Kernel 3.0) where I observe time-mismatches on VMs.
The clocksource=jiffies made it worse in my case - but in yours it might help.
Currently the support is focussing on the high-precision-event-time... | How can I find the cause of clock drift on a custom embedded system? |
1,470,727,670,000 |
I have a single board appliance that runs Debian 10 on a chunk of flash. UBIFS is used, and is split into two volumes: an ro roots, and an rw /var. I have found that under power cycling/reset conditions, that I can end up with 0 byte files. I keep my "settings" in /var/opt/myApp. Changing the mount option of /var to i... |
Here is my opinion: Sorry for verbosity in advance.
When we are specifically talking about ubifs we should always either sync / similar options.
ubifs supports write-back caching
That means changes written on the files do not go to flash directly. They are stored on the page cache first and later written to flash.
(R... | To sync or not to sync in an embedded environment? |
1,470,727,670,000 |
I'm working on an embedded system and want to make it boot faster.
I already stripped a lot of things. Now I don't know how to improve it further.
Here is my systemd-analyze blame:
4.457s dev-mmcblk0p2.device
1.303s systemd-journald.service
913ms systemd-journal-flush.service
793ms systemd-sysctl.service
67... |
I found out, that I had to modify the kernel commandline in U-boot.
The commandline now Looks like this:
# cat /proc/cmdline
root=/dev/mmcblk0p2 rootfstype=ext4 rootwait console=ttymxc4,115200 quiet consoleblank=0 coherent_pool=32M
| Systemd Boot Optimization dev-mmcblk0p2.device |
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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 map to one physical Ethernet port, eth1 to the next, etc.
My Linux "distribution" is home-grown, and I use devtmpfs for po... |
This works for me with Linux 3.9.0 on an x86_64 architecture.
#!/bin/sh
# This assumes the interfaces come up with default names of eth*.
# The interface names may not be correct at this point, however.
# This is just a way to get the PCI addresses of all the active
# interfaces.
PCIADDRLIST=
for dir in /sys/class/ne... | How do you ensure physical network interfaces always get the same interface name across reboots on an embedded Linux system? |
1,470,727,670,000 |
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/
root@Xilinx-ZC702-2013_3:~#
root@Xilinx-ZC702-2013_3:~# cd /mnt/flash/
root@Xilinx-ZC702-2013_3:/mnt/flash#
root@Xilinx-ZC702-2013_3:/mnt/... |
When you see weird kernel behavior, dmesg is a great first thing to check. In your case, it gave an important pointer:
4 ofpart partitions found on MTD device spi32766.0
Creating 4 MTD partitions on "spi32766.0":
0x000000000000-0x000000500000 : "boot"
0x000000500000-0x000000520000 : "bootenv"
0x0000005... | While trying to open /dev/mtd2 for read/write access: Permission denied |
1,470,727,670,000 |
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 default the system has one UART enabled, UART0, mounted as /dev/ttyS0 which is also used/invoked via the bootargs console... |
mknod /dev/ttyS1 c 4 65
(if /dev is read-only use any writable directory mounted without the option nodev)
If the node is created without errors you can check if your patch is working reading/writing to the node or with any terminal emulator.
The problem is that the node isn't created?
If you're using some auto-magic ... | ttyS1/uart1 initialised but not accessible through /dev/ttyS1 |
1,470,727,670,000 |
Reading from /proc/PID/stat a lot of information can be processed. I would like to see how many percentages has been used of CPU power by this process. There are a lot of variable around here (utime, stime, cutime, cstime, gtime, cgtime) but they are in jiffies. The problem with this that jiffy depends on speed of the... |
The jiffy does not depend on the CPU speed directly. It is a time period that is used to count different time intervals in the kernel. The length of the jiffy is selected at kernel compile time. More about this: man 7 time
One of fundamental uses of jiffies is a process scheduling. One jiffy is a period of time the sc... | What is the connection between jiffies and IPS? How to convert jiffies to IPS? |
1,470,727,670,000 |
I would be interested in finding ways to reduce the boot time, specially in embedded-related environments.
I've read somewhere of a method to avoid the kernel to load some drivers or modules but I'm completely lost and all the information I find on internet is quite complex and dense.
Could anyone please suggest the g... |
The arch linux documentation Improving performance/Boot process may help you to learn how to improve the boot performance.
Use systemd-analyze blame to check the timing for the enabled services, or systemd-analyze critical-chain to check the critical points then disable the unwanted services through systemctl disable ... | Reduce Boot time |
1,470,727,670,000 |
In the future I may be building a system with an embedded operating system. Given the commercial properties of this system, it will make sense to have all of the internals as closed source as possible.
I have seen in the past many router manufacturers being forced to release source code due to them using a system unde... |
A Linux distribution consists of many pieces. All the pieces that are based on software licensed under the GNU GPL and other copyleft licenses must have the code source released. For example, if you ship something built on a Linux kernel, you must provide the Linux kernel source as well as any patch that you have made... | Is there a variation of Linux or Unix that does not require open licensing? |
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I recently dug out some prototyping equipment from the trash and I want out figure out what the heck it is. It has a port labelled 'Ethernet' and when I plug it into a router the lights flash like its trying to pull an ip but it does not.
My router is running DD-Wrt and I have a netbook with Knoppix I can use on the r... |
Perhaps the easiest way is to use your netbook - just because you don't have to filter out unrelated traffic later. You can use tcpdump to dump all traffic on your ethernet device. After starting up tcpdump you connect your equipment. After nothing flashes any more you disconnect it and you can look at the dump with w... | Ethernet Sniffing Embeded Device |
1,470,727,670,000 |
I would like to have a service which behaves differently on first run and on restart of service. Is this possible with systemd? (I use systemd in my embedded os).
I tried with ExecReload and ExecStart, but ExecReload is run only when I use command "systemctl restart". On the other hand ExecStart is run after service ... |
You could use systemctl set-environment to push some values into future runs of the service. For example, with a unit:
[Unit]
Description=testing
[Service]
Type=oneshot
ExecStart=/my/command myarg1 ${MYDONE}
ExecStart=/usr/bin/systemctl set-environment MYDONE=1
[Install]
On the first systemctl start <unit> the last a... | Systemd - how service can determine first run from restart run? |
1,470,727,670,000 |
I have an embedded system built using buildroot. I have had a number of network issues, one of which is that my machine cannot see its gateway despite it being on the same subnet. I have tried using wireshark to analyse what is going on without success so as a last resort, I am considering trying to turn off support f... |
I agree with Ulrich, that this doesn't sound like an IPv6 problem. However, here's how to disable IPv6.
In /etc/sysctl.conf set the following options:
net.ipv6.conf.all.autoconf = 0
net.ipv6.conf.all.accept_ra = 0
net.ipv6.conf.all.disable_ipv6 = 1
If you don't have /etc/sysctl.conf just create it and add those lines... | How can I disable IPv6 in custom built embedded setup |
1,470,727,670,000 |
I have compiled an embedded Linux with Buildroot for i386. I didn't edited much, just defaults. Now I want to run it under qemu. But the only thing I see is this:
I'm running qemu with these options:
qemu-system-i386 -kernel vmlinux -hda rootfs.ext2 -m 256
Why this is happening? I have compiled like the example in t... |
Commands that just work
To make absolutely sure that it will work, we can make Buildroot build QEMU for us, and use the exact QEMU CLI provided by Buildroot at: https://github.com/buildroot/buildroot/blob/2019.05/board/qemu/x86_64/readme.txt
git clone https://github.com/buildroot/buildroot
cd buildroot
git checkout 2... | How to use qemu to run Buildroot Linux images? |
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I was asking myself if a certain dtb that works with linux kernel version 3.18 is compatible with a linux kernel version 4.9.
I suppose not, because kernel code concerning the device tree likely changes over the time, but it somehow has to be compatible otherwise multiple dts/dtsi files have to change all the time.
I... |
The Device Tree is supposed to be a stable ABI so a device tree written for any version of the kernel should work with any following kernel version.
However, for practical reasons, this is quite often not the case. You can have a look at the following presentation from Thomas, explaining why:
http://free-electrons.com... | Is a device tree blob tied to a specific linux kernel version? |
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I'm trying my hand at creating a very minimal custom Busybox/Linux distro, a task that is admittedly above my head, but I figured I'd give it a shot. My issue is that whenever I try to run a C program that is not Busybox or a Busybox utility, ash complains and tells me that the file is not found. I mounted the partiti... |
My guess is that you don't have the correct dynamic linker on the Busybox system.
On your Arch system do this:
ldd ./simplestprogram
I imagine ldd will give you output similar to this:
linux-vdso.so.1 => (0x00007fff9b34f000)
libc.so.6 => /lib64/libc.so.6 (0x0000003b19e00000
/lib64/ld-linux-x86-64.so.2 (0x0000003b... | Minimal Busybox/Linux Installation - Won't Run C |
1,485,283,266,000 |
I have been using the following command on my system to create the .cpio archive to create an initramfs for my embedded target device
sudo find . | cpio -H newc -oc > ~/initramfs.cpio
This has always worked for me without any problem. Yesterday I was generating a new archive and I received the following error:
cpio: ... |
The first error is because you're passing both -H newc and -c. You have to make up your mind on the format of the archive you want to generate. The "Operation not permitted" is a bug in GNU cpio, it's passing wrong arguments to the function that outputs that error message and should exit there.
The other errors are be... | What is the meaning of the errors from my cpio command? |
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I want to test the touch panels on embedded devices like iPhone, iPad and Kindle against following criteria:
Do a gesture, like tap, swipe, pinch ( zoom in/out) 10000 times and validate that every time the gesture was indeed detected and was detected as a tap, swipe, pinch ( zoom in/out).
Do a tap on the touch panel... |
Jason Huggins gave a fantastic talk at PyCon 2012 that described, in great detail, a robot that could play "Angry Birds" on the phone:
Worth watching the talk, it was very entertaining.
Most importantly, the plans for the hardware and software of the core toolkit, BitBeam, are online in a github repo. I'm sure it w... | How to test the touch screen on embedded devices like iPhone / iPad / Kindle? [closed] |
1,485,283,266,000 |
I am currently developing inside an embedded Linux environment (kernel 3.10.0), and while goofing around in the procfs mount of the system I found that all processes present the following file in their /proc/[pid] folder:
-rw-r--r-- 1 root root 0 Feb 22 09:10 make-it-fail
Just for testing, I launched from... |
I was investigating a little your questions, as I was becoming suspicious from reading this Injecting faults into the kernel that make-it-fail was a flag.
Actually it is confirmed reading Injecting faults into the kernel:
So there are a number of options which can be used to focus the faults
on a particular part of t... | Meaning and usage of /proc/[pid]/make-if-fail |
1,485,283,266,000 |
I have an interface for RS-232 communication. I need this interface for simple communication (no parity bit or flow control → TX, RX and ground) but now I have quite 4 pins unused (RTS, DTR, DCD/DSR, CTS) and wondered whether I could misuse these pins for some other signalling and for this I would need a way for readi... |
RTS and DTR are output pins - which you can set.
DCD and CTS are input pins and can only be read.
The device is probably set for hardware handshaking by default. You can change this using tcsetattr (see CRTSCTS). Then you can use the TIOCMBIS ioctl to set RTS and DTR
Good references are:
Linux Serial HOWTO
Linux Seri... | How to readout unused serial pins (RTS, CTS, etc.)? |
1,485,283,266,000 |
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 the time if it's available, then fall back to ppp0 if eth0 is down?
Also would such a handoff be transparent to the netwo... |
The plain protocol is specifically designed to do what you request. With MPTCP you can
establish a connection to your peer
tell the peer your available endpoints (like IP address of ppp0 and eth0)
from this point all negotiated paths can be used, but you also can define
one link as active and the others as fallback
... | How configurable is MPTCP? |
1,485,283,266,000 |
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 ntpd, but the date and time haven't updated.
|
It looks like you have the Busybox version of ntpd. Here's a useful HOWTO:
http://wiki.openwrt.org/doc/howto/ntp.client
For example:
ntpd -q -p ptbtime1.ptb.de
| Setup ntp client with embedded device |
1,485,283,266,000 |
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 it does not even include passwd.
On the other hand I don't want to build busybox from busybox.net sources for stability... |
If you need a .deb customized on the fly
mkdir /tmp/bb
cd /tmp/bb
apt-get source busybox
sudo apt-get build-dep busybox
cd busybox-1.20.0/
fakeroot debian/rules build
make -C debian/build/deb/ menuconfig
# enable passwd
fakeroot debian/rules binary
but probably the best would be to add a custom package inside debian/... | How to custom build debian's busybox? |
1,485,283,266,000 |
I have a small embedded linux kernel and file system created via buildroot that is installed onto a compact flash drive running on an x86 board. I am using an initramfs (due to power loss concerns) but mounting a small number of directories on ext3 partitions on the CF drive for data that has to be persistent. However... |
No, this is not a bad idea. Many devices that you may find around are running linux without swap partition. For example, there are many DLink router models with linux inside. The only possible issue is that it may run out of memory. However, with embedded solutions this should not happen if the system is properly desi... | Is it a bad idea to not have a swap partition on an embedded linux setup? |
1,485,283,266,000 |
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-AltArch-ppc64-Minimal-1611.iso of=/dev/sdc
When I try to boot the freescale board using this SD card I get following message... |
Following is the reply I got from CentOS mailing list:
The CentOS 7 ppc64 and ppc64le variants are supposed to be installed on IBM Power (or compatible boxes, like Tyan or others, from the OpenPower
consortium)
Nothing would work "by default" from a CentOS side, but something could probably be done if you build a Root... | Is CentOS PPC64 supported by Freescale T2080 RDB? |
1,485,283,266,000 |
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?
|
A couple of ways:
If you can get SMART data from an SD cart with smartctl, it may have a bytes written counter (no idea if this is possible). This will be the most accurate, as it will count all partitions and also not be lost over reboot. It may also be able to count any write-amplification caused by erase block siz... | How to determine how many bytes / hr are being written to my SD card |
1,485,283,266,000 |
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 figures or even sprites. I am searching something. Can for example SDL run on frame-buffer without X, or there is similar ... |
DirectFB might be what you are looking for. If you needed higher level API, SDL should be able to use it as its backend.
| What is the easiest way to draw graphics on Linux framebuffer? |
1,485,283,266,000 |
I'm working on an embedded Linux (4.1.15) bash script wherein the bitrate of a CANbus may be one of several possibilities. When my module comes online it comes up at the first bitrate in the list, checks for traffic, and, if no traffic, cycles through each bitrate in like manner until traffic is detected.
My initial ... |
(My timeout command doesn't use -t, but there seem to be different versions). By putting the timeout part inside the $(), it should be able to signal the canbus command, and at least the assignment to output should always create the variable.
output=$(timeout -t 1 candump can0)
| Bash: Determining if CANbus Bitrate is Configured Properly |
1,485,283,266,000 |
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 initialized multi-threaded application as well as various daemons running etc.
From what I have read, using stime() or... |
My solution was to write directly to the rtc using ioctrl. Here's an implementation for anyone who comes across this:
#include <linux/rtc.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/ioctl.h>
int main(void)
{
int fd;
fd = open("/dev/rtc0",0);
if (fd < 0)
printf("Can't open rtc!");
struct rtc_... | Embedded Linux: setting the time without NTP |
1,485,283,266,000 |
I have a small embedded system that I am working on that needs to be able to reduce its brightness for power saving reasons. The screen is connected by LVDS with separate Inverter Power Output connection providing the backlights power. The system is running Debian 3.2.68.
I have tried several approaches to this such a... |
The issue was a missing driver. After being in contact with advantech they had drivers built for both 32 and 64 bit Ubuntu which were not on their website. The Ubuntu drivers (of the correct architecture) work on Debian enabling brightness control.
| Trouble changing backlight brightness (/sys/class/backlight folder empty) |
1,485,283,266,000 |
*tldr; I would like to generally understand how the world of linux / embedded linux works. What do I need to do to take the Linux mainline and compile/deploy it on a board with different processors and peripherals, from scratch.
How I currently See It Working:
Steps to get Linux running on arbitrary board:
Get so... |
From my small experience with router hardware I played with, I can say that this is a dumb small hardware picked up just to do one thing.
At hardware level, it's simple:
U-Boot there is not only bootloader, but a BIOS in PC terms. So it's not only a bootloader, but also it initializes all hardware. At start, CPU execu... | Linux/Embedded Linux - Understanding the Kernel and additional BSP specific components [closed] |
1,485,283,266,000 |
I'm using a DTS file for a Duovero Parlor board. To this board I've added some SPI devices. My first (a display) works perfectly so I have that entry correct at least. I want to add an entry to support the SPI connected NXP SC16IS752 UART controller. (There's been a patches on lkml recently I want to try).
This is my ... |
The issue with your clocks, is that clocks declared outside the TI
clock domains are not parsed and set up correctly in 3.17. This issue is
resolved in kernel version 4.0.5.
The required changes occurred in the function omap_clk_init at the end
of /arch/arm/mach-omap2/io.c, there is an extra call there to
of_clk_init(... | Clocks entry in SPI device tree entry |
1,485,283,266,000 |
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 that reads the touch events and calls our callbacks.
These callbacks simply forward the x,y events to the application.
We ... |
First and foremost, your touchscreen needs a kernel device driver. It may be compiled into the kernel or as a module. The loaded driver will generally create an event in /dev/input/. This event is used by X. You can test touch input event with evtest:
evtest /dev/input/event#
Additionally, the device should be li... | How to setup touch screen for X11 |
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