i Just got the book Linux Kernel Development by Robert Love . It has lots of places where you are required to modify and build the kernel . So how should i go with it . Is it better to use a VM , or should i somehow get a proper test machine for it , since i dont want to goof up on my system and data.
A VM has the advantage of offering snapshots. These allow you to save the state of the machine - if the kernel build doesn't work you simply restore the snapshot, and you are able to take as many snapshots as you have disk space to store them. You are also able to clone and re-deploy the VM image, so you have many identical systems to test on.
The same experiment on a physical machine would require far greater effort (ghosting/cloning the disk, re-installing the OS etc).
VirtualBox is free, cross-platform virtualisation software.
There are a lot of tutorials on the web about this topic, e.g. here:
http://www.digitalhermit.com/linux/Kernel-Build-HOWTO.html
http://www.kernel.org/pub/linux/kernel/people/gregkh/lkn/lkn_pdf/ch04.pdf
You could do either or both. An alternative somewhere in between is to setup a dual boot. This is a little riskier than a VM, but not too much.
coLinux
or run linux iso image using QEMU on windows
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I have a project and the files are on Guest OS (Red Hat Enterprise Linux) with Virtualbox, my host OS is Mac OS. I used to coding right in RHEL with editor Atom. But my boss told me that it's inefficient to code in a Guest OS, well, it makes sense because Mac OS or Windows is more responsive than linux, so I changed my way:
Copy the whole project located on RHEL to a share folder between Mac OS and RHEL using rsync
Code with Atom in Mac OS
Copy back the project in share folder to the original project in RHEL by rsync
I'm using Atom (not vim in RHEL) because it can edit the whole project in one window which is convenient for my situation. But there is a problem: after copying back the project in Step 3, git status shows everything has been changed even though I just edited only a few files. That is a little annoying.
Is there any better way to code in such environment? any advice is appreciated.
BretzL's suggestion to use shared folders is a good one, but I think it's important to address the underlying issue: your boss' assumption about coding being inefficient or slow just because you're working on a VM is simply not true.
It sounds like your new workflow, which was instituted as a result of his/her advice, is causing you to have a harder time developing that you did on the VM. The shared folders will help with that, but if you have the VM configured to have access to enough cores and memory, then its performance for most tasks will be fine, and there may not be any problem with developing on the VM directly. I do a significant amount of development on a VM, and haven't had any issues. You may experience slower builds on the VM if you're building whole kernels or other large projects, but if that's not the case, it should be fine.
If you didn't have any performance or productivity problems before forcing yourself to work outside of the VM, then... it wasn't a problem.
(I also have an issue with the assumption that Linux is always less responsive than Windows or Mac OS, but that's a debate for a different day.)
VirtualBox supports shared folders, so you dont need to rsync back and forth. Just mount the shared folder into where your application server on RHEL guest expects the code.
I also recommend you take a look at https://www.vagrantup.com/ for managing developer VMs.
I'm running embedded Linux (Debian on ARM/X86_64). Since it is very much like a full OS, with some hardware differential and a different platform, you may consider it as a regular machine. So, this will be used in the robotics field where the computer will ALWAYS be hard reset by turning off power. It would disqualify me to use a UPS so I would need to make the system infallible.
I'm running some processor-intensive tasks, like OpenCV and OpenNI and OpenKinect. How do I use an uber-powerful filesystem, like ZFS to mirror the entire disk on the SSD for error correction? Does ZFS perform well in Linux? I'm still kinda a newbie in Linux so I don't understand it's internal workings.
My list of possible platforms are:
--Debian#RaspberryPi
--kUbuntu#ODROID-X2
--Ubuntu#PandaBoard
--Ubuntu#NUC-i3/5.
Also, how can I make sure the filesystem doesn't get damaged during reset? I need the computer to start in good time, A.K.A, <3 minutes for the competition.
I will probably be using a 32GB SSD, so I guess a 16GB partition mirrored 2x works or 12 # 3x. I only need to get an OpenCV install working because the code will be downloaded from a SAMBA NFS automatically!
Thanks for your help and good luck ;)!
ZFS is not suited for low memory systems. It do perform well on system with 4GB of RAM and more.
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. :)
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.
Actually I will want to use that JeOS for our webserver. Is it a good choice?
Thanks for piquing my interest. From the Ubuntu website:
Ubuntu Server Edition JeOS (pronounced
"Juice") is an efficient variant of
our server operating system,
configured specifically for virtual
appliances. Currently available as a
CD-Rom ISO for download, JeOS is a
specialised installation of Ubuntu
Server Edition with a tuned kernel
that only contains the base elements
needed to run within a virtualized
environment.
It looks promising to me - I run several full Ubuntu 8.04 VMs so I'll certainly check it out. Why not just try it?
Be aware that the kernel it installs is striped down to only have the stuff required for virtual machines, therefore you might have problems accessing the network from a real machine. (Note that the install-CD kernel isn't the same as the installed kernel as well).
If you can bypass that (IIRC I booted from the CD, and downloaded the normal server kernel and it all worked fine), then you end up with an absolutely minimal Linux system, but backed by the full Ubuntu repositories, so it's an excellent base for a server.
Also note minimal really means minimal - no cron by default for example.
Is it a good choice?
If you plan to run JeOS in a virtual machine, then yes, this is a good choice.