I am new to linux programming & interested to tweak linux kernel(though I am not sure, what to tweak, I am planning to write drivers for particular device). To learn internal of kernel, I have started from historic kernel release (first release).
My problem is, how to test whatever changes I am doing for development, without disturbing my current os environment.(ubuntu 12, 64 bit). Is there any way like virtual box, sandbox?
Along with these, if anybody send some good approaches to learn these things, I would be really greatful.
Thank You.
If you're new to linux programming then you really don't want to be tweaking the kernel. You really want to be an advanced programmer capable of programming drivers and complex software first.
But yes there is, you can can create a virtual machine using openbox or vmware. If you're really keen on tweaking the kernel you probably want to first just try compiling and configuring the kernel and seeing if that works.
Also make sure you're well acquainted with how the kernel works and advanced OS designs in general.
Search in google fr "Kernel configuration" you u will get many links how to configure your own kernel.
And one more thing do not use a outdated version of kernel ,always use latest stable release , because a lot of code and API is changed in new versions and no book in market is updated so ,, u have to read from kernel documentation. Thats the best way to learn the most updated information about linux kernel
Yes, you can test your changes on any of the commonly available virtual machines (VMs); that way, whatever changes you make to the VM kernel won't affect native OS.
Personally, I prefer using CentOS 64 bit on VMWare Player. With this setup, I got away with minimal system maintenance while was able to focus on the actual job at hand. Once the VM is up & running, you can download and compile one of the latest stable releases from kernel.org. Instructions on compiling your downloaded version of kernel could be found here and here; however, this may require little tweaking based on your actual setup. Once the VM is running on your desired version of kernel, using a combination of cscope and ctags will help you immensely in kernel code browsing.
Finally, if you want to become a serious kernel programmer and write your own device drivers, you need to get familiar with it in the first place. Below are a few excellent references -
Linux Device Driver by Corbet, Rubini, Kroah-Hartman, 3rd edition
Linux Kernel Development by Robert Love, 3rd edition
Understanding the Linux Kernel by Bovet, Cesati
Linux kernel source (ideally placed into your /usr/src/$(DESIRED_KERNEL) path, symlinked to /usr/src/linux)
Going through these books is a tedious job and chances are that you may hit the roadblock from time to time. kernelnewbies mailing list and StackOverflow are some of the few reliable places where people would be happy to answer to your queries.
Good luck!
I'm studying for a CS degree, and I need to install Ubuntu for a computer systems class. We are going to do low level Assembly optimizations and stuff like that, so they don't want us to install it in a VMware.
Now, I don't want to do a regular dual-boot install, because I've already done it on my previous computer a couple of years ago, and wrecked my hard-disc with the partitioning. Wikipedia says you can use Wubi to boot Ubuntu from ISO, or install it to a flash drive and boot it from there, and then thus remove the need for partitioning.
Now, my question is - how different it is to program for Ubuntu booted from a regular hard-disc partition, from a Wubi ISO, and from an SD card? I guess the programs will work the same on all options, but we're going to do play with low level Assembly optimizations - can I expect to face any difference in that department?
I'm not sure I'd go this route if it were me personally.
You should be fine in terms of whatever bare metal type stuff you want to do -- you're working with memory, the cache, the chip, etc, so your disk drive shouldn't matter (unless you're doing stuff to the filesystem or something).
Where I think you might get annoyed is the logistics of setting up your development environment. Everytime you boot from your USB stick, you're going to need to sudo apt-get GCC, scite, et. al, load your files on into directories that you want, and then get started. That's a hassle. You could optimize this somewhat by creating a custom ISO of your environment using some kind of tool (you might be able to do it with Clonezilla), but still.. yuck.
I would suggest (speaking of Clonezilla) that you snapshot your hard drive, go ahead and install dual booting with Ubuntu, and then you have a backup if anything goes wrong. Or, I'd think you could get by using the school's machines. Don't they have any Linux boxes that you can ssh into, if not use in labs?
Anyway, good luck. :)
was wondering - if knowing The Linux way of life or the Linux architecture, would give a better frame of mind for programming on embedded devices especially when they have some kind of OS in them.
Just want to be sure that I did not miss a major thing :)
Note:
I come from a windows background, can program in C and C++.
Passionate and finally want to get started into Embedded programming. I would like to start by doing typical hobbyists project at home.
It would be nice if anyone would also comment on BeagleBoard as a starting point for me.
"Embedded" is a fuzzy word. There are two categories:
There are realtime embedded systems: microcontroller/microprocessor applications that are intimately communicating directly with the hardware on a low abstraction level. Typical applications are control systems/automation, industrial, automotive, medtech, household electronics, data/telecom communications etc.
And then there are fluffy embedded systems: various laptop:ish computers, embedded linux, embedded windows, phones and phoney operative systems, anything involving internet, human-machine intefaces etc.
People working in both categories will firmly state that they are working with embedded systems, while the latter kind are often just doing another flavour of desktop applications. Depending on which category you are aiming for, Linux may or may not be a merit. The telecom branch for example, overlaps both of these categories, and they are often using embedded Linux even for non-fluffy applications.
In either case, *nix may be used as the development platform, so knowing it won't hurt.
Yes and no. Mostly yes.
Lundin correctly described the "two worlds of embedded" (although the border between them is very fuzzy).
If you're writing for "higher embedded", like Android, or other devices that run Linux, then definitely expert knowledge of Linux will be of much help. You still need to know some "bare bones" and don't get scared when you see the likes of &=~ operator in C, but knowing Linux - the Linux of the old, where you configured stuff by editing files in /etc, where you compiled your own kernels for everyday use, where you would build software from tarballs, that's what helps. Knowing modern Linux - Gnome, gconf-editor, Synaptic and the likes will not be of much help.
Then next, if you're programming devices without OS, in the middle area - fast and strong enough to run C programs, but not the OS, you still need Linux. Because crosscompile. You don't need actual Linux. Cygwin is okay for that. MinGW may suffice. Still, you will probably need to be able to build your own crosscompiler (based on GCC), linker, debugger, make tools, and the rest of "backbone" of the IDE. Unless your chip supplier is awesome and provides a complete toolchain with IDE.
Only when you're into tiny processors, you don't need Linux. Stuff like car alarm remote, christmas lights blinker, car tire pressure sensor, battery level monitor - stuff that can have 16 bytes RAM, 1KB EEPROM, and the rest of CPU to match, you will need to use an IDE that works with this CPU, no OS, no C compiler, nothing remotely close to Linux - the IDE will most likely be Windows based.
I'd say you really do not need to know Linux for embedded programming. Many companies developing embedded software do it on windows and have no contact with other OS.
But sure, knowing more makes you more versatile, and general knowledge makes you a better engineer. This includes different OS as many other things.
When it comes to BeagleBoard, it depends on the kind of application you are interested in.
If you want to understand the low-level, I would start on a simpler processor and learn how to use peripherals, hardware interrupts, debouncing signals... There is an educational point in doing this yourself some time.
I suppose you can also skip that and start with an ARM-A8 and possibly an embedded OS, it's just not the path I followed.
What I am about to say may cause a flame war, but...
I have found that Linux is a much more productive development environment than Windows. At my previous job, we were developing firmware for managed switches and industrial automation equipment, which ran an embedded Linux operating system. All the developers had both Windows and Linux boxes, as the user interface software only ran on Windows. We all used Linux for developing, though, as it was simply easier.
At my current job, the only choice is to run Windows, but to make it more productive we are running Cygwin, which provides a Linux-like environment. It is very difficult to develop software on Windows that is not specifically for Windows.
As for developing for an embedded system without an OS... I have an Arduino that I play with occasionally. I have programmed it both from Windows and Linux, and have found the experiences fairly similar. Using Arduino's own tools, Windows seems to run a bit more smoothly, but if you want to hack on it and make something interesting, you're better off using Linux.
Personally (and this will likely provoke some nasty comments), I feel that Linux is best for doing productive work, and Windows is best for playing games.
So basically, this all boils down to this: Try using Linux for developing your project. You will probably find it to be a much smoother, more productive experience. If you don't like it, you don't have to keep using it. But the experience will probably be worth it.
Edit (due to question rewording): Knowing the "Linux way of life" is unlikely to help much when coding for an embedded project that is not running Linux itself. As I understand it, the Unix philosophy is about two main issues:
Each tool should do one thing and do it well (don't make something that tries to be everything).
Whenever possible, data should be plain text (allows for simple piping through processes and searching for content).
If you are working on a system without an operating system, you are writing code for a compiler and not likely working with a full shell at any point. You also are unlike to have any sort of file system. So both of these points are moot; you are not likely to gain anything concretely related to embedded programming by studying Linux, although it certainly couldn't hurt :-)
I really think if you want to learn a little about embedded sphere you should not start by using an OS directly. Prefer to have hands on a small low level project then add an OS if it's really needed for your final application.
I don't think setting up an OS into an embedded device will be easier than starting from scratch. It will bring you some functionalities (that I am not sure you really need to learn embedded) but it will bring you lot of hard debugging time in case of problems in the OS port.
I have been doing embedded programming for 10 years, currently for networking equipment and before that Apache helicopters. Both companies had POSIX-like operating systems on the target, but not embedded Linux directly. My current company uses mostly Windows for individual developer environments. However, we do have a few Linux boxes hanging around for special purposes. My previous company used a mix of Windows and Sun Solaris Unix. So wherever you go, you may not use Unix or Linux on your day to day computer, but you are likely to come across it at least occasionally.
On the other hand, I've known developers who have programmed on Linux for embedded Linux targets their entire careers. It really depends on the company, as smaller or newer companies have a tendency to use Linux more than corporations. However, using embedded forms of Windows on targets is very rare in my experience. I know devices are out there, but I've never personally met a developer who worked on one.
Anyway, Linux is free to use and has other benefits besides being good for a job. There's really no downside to giving it a try for a couple of months, other than giving up some of your time.
Linux is growing in embedded... see latest research:
Top 10 trends for the embedded software and tools market in 2011 - VDC research
Android Becomes Number One in U.S. Smartphone Market Share
Knowing the Linux way of life will definitely be a plus in embedded domain provided the kind of apps you are interested in are contained in the above mentioned links.
understanding Linux architecture will be over kill (although basic overview is good) before just starting in embedded field
e.g. to cut a tree you don't have to invent an axe - just start using one, then gradually you could learn to sharpen the axe
Its better to get started small - get hands-on, and focus on specific areas as is the need of the hour. grow with your work and work keeping your goals in mind
you will surely gain much faster and not get stuck in self loop - R&D to do R&D ;)
Only if you want to embed Linux! And as an embedded systems developer of some 22 years, I would suggest that Linux is unsuitable and unnecessary for a very large proportion of embedded systems projects.
Understanding the workings of an RTOS, and real-time priority based pre-emptive scheduling and IPC mechanisms would stand you in better stead. Take a look at this for example.
I'm looking for a really really small linux distribution or process of making my own that's sole purpose is to get an air application to launch full screen and stay there; Essentially I'm building a home kitchen computer that runs entirely as an AIR app.
I have looked into using windows xp; and windows xp embedded but they pose so many issues I figured I'd try modern linux.
I have also seen TinyCore Linux which looks interestingly small but not sure what issues that poses in regards to running AIR and "hardware" accelerated display. I've also thought about stripping down an Ubuntu installation but I'm sure somebody must have done this already; google is just failing me right now...
I'm also interested in running an "embedded" version of say android and running the air app on some arm-based hardware again; with just the AIR runtimes only - although this is less preferred as it's more complex.
I'm also hooking this up to a touch screen monitor (not yet arrived) so I'll need to hunt down or write some drivers for translating the touch events into something AIR can understand... (this was my main intention for using windows in that all the drivers will just work).
What I'm after
Minified Linux kernel with JUST the drivers for the box I need
X Display with accelerated graphics support (Doesn't have to be X if AIR can run on a frame buffer?)
Running a Full screen AIR application (simple enough)
Ability to write back to the filesystem (enough support for AIR)
SSH Access for remote control
Samba for updating the filesystem (easier to maintain the system)
Touch screen support (3M Ex III I think...)
Audio support
Don't need
Don't need any window manager or any other GUI tools unless required by AIR
Don't need any toolbars or file managers or anything; The AIR app is the "OS"
Don't need any package managers or repos
Don't need multi user or logging in; everything can just run as an unprivileged account
Don't need to
I don't mind hand crafting the filesystem and configs if that makes it easier; I'm mainly looking for a "filesystem" that is as tiny as possible that I can just plop my AIR app into and write some scripts to get it to start when the X server starts
Thanks,
Chris
Try an embedded Linux build system such as Buildroot. It can build an entire system from source, and be very lightweight. The basic system is less than 1 MB in size.
Ended up going with Tiny Core. Very tiny and quick to boot up. You can also write extensions for it and you don't have a persistent drive which allows you to just switch the thing off without worry that it's going to break something -- exactly what you need in a kitchen :-D.
My current plan is to:
Just set up a working version using Ubuntu as this is mostly supported by Adobe
Slowly strip it back and try and get as little things to start as possible on boot
Try building my own distro/package from source and selecting only the packages I need
Compile my own kernel with nearly everything turned off and just leave on the things I need
I will have (maybe) to work soon on ARM platform hosting a linux distribution (I don't know which distribution ..).
I know the project concerns video streaming, but I can't tell you more. Actually I only received the announe, and meet nobody yet.
I've never worked on such platform. So the idea for me is to test before the project starts.
What would you advise me to undestand how works such platform ? Internet links? Tutorials? Tools
Morevover, as I don't have any ARM processor at home (well only my iPhone ..) Which virtual machine would you advise me? (I clearly don't want to lose time installing and testing every one of them.)
I am aware of this page on wikipedia. Which one is the more appropriate running on a MacOS X 10.5/intel platform? Which linux distribution to install on the virtual machine?
I know the topic is quite wide, so any idea is welcomed! :-)
For a virtual machine that can emulate a ARM platform try QEMU. You can install a ARM-based Debian Linux distribution and tinker around with it. A google search on ARM, QEMU and Debian will get you started.
Also: Don't worry to much about the ARM CPU. You will use linux, so all the low-level stuff is already done for you. It's much more important to learn how the linux boot process works. How to install stuff ect. You will rarely (if ever) notice that you're running on a ARM device. The big difference to a PC running linux is, that the ARM will be a lot slower.
If you're looking for a real piece of hardware to play around with I suggest that you take a look at the beagleboard (www.beagleboard.org). It's cheap (around $150) and runs (among other things) various linux distributions.
With the beagleboard you'll get the whole linux cross compilation experience if you want (be warned: you'll pull your hair out).
I can't answer all of your questions, but there's a full port of Debian GNU/Linux on ARM. Works fabulously in my experience (I've tried it on a QNAP). Everything that's available in Debian works on QNAP now! So it's probably easiest to first try Debian tools and packages that come close to your project, and then continue from there.