I'm working on the linux kernel's secret-ish eudlypta challenge and while you can't post any actual code, I figured it would behoove me to post different things I found helpful for setup, configuration, reference, etc.
- You never know what stupid things you could do to your own kernel, so use a VM.
- Install VBox on fedora
- Vagrant makes it painfully easy to set up a virtual box with command line access...
- Vagrant download
- This process can be fairly complicated depending on your OS. Check out these instructions if you need more help.
- As a sidenote, occasionally it may be the case that your actual hardware is not set up to enable virtualization. As a last ditch attempt (I had to do this) check the specs for you computer/manufacturer to figure out how to boot into the BIOS and make sure that virtualization is enabled. I have a Lenvo: how to enable virtualization in BIOS on lenovo
- Use this vagrant box... although the thing you really need from the link is this one-liner:
vagrant init ubuntu/trusty32; vagrant up --provider virtualbox
- Once you get the vagrant box initialized you just need to run
vagrant ssh
- Vagrant is pretty cool (while linux containers are waaaay cooler, containers don't get their own kernel), so if you want to do more with the box I recommend going here, playing around with some exercises and reading some of the links.
- This is the part that I know much less about, but I found this link pointed me to some packages I needed.
- First Kernel Patch
- The linux kernel coding style guide-- an absolute must read.
- When in doubt default to this book. This is the 2nd edition to The C Programming Language by Kernighan and Ritchie. Linux calls it K&R in the codying style docs.
- Some very highly recommended reading on a really great site.
- directions for code and makefile
- Debugging and printing messages kernel style is important.
- Keep in mind with kernel printing you can use the printk functions with an appropriate log level, however, when you run the checkpatch.pl script it will yell ("warn") at you to use the alias functions, e.g.
printk(KERN_DEBUG "I am a debug message");
/* versus */
pr_debug("I am a better debug message");
- Searching the source code can be invaluabe when looking for a solution. Using ctags or cscope can greatly assist you here.
- cscope makes a database of the source code that you can use to quickly search.
- ctags are also a useful tool for jumping around source code.
- This is an excellent how-to that will help you navigate the gritty gitty core of torvald's kernel.
- This is a guide to building your own linux kernel from the source.
- This is a book about customizing and building a kernel... Probably the best resource. Keep in mind it is for the 2.6 kernel so some of the information may be a little dated.
- I ended up compiling and running my kernel natively. Fedora uses grub2 which can be a moderate headache. I highly recommend using the program "grub-customizer" if you need to edit your configuration after you have installed the kernel.
- Obviously there is kernel documentation and you should build it so you can have access to the fabled man 9 pages.
// In the kernel source directory run (make sure you have xmlto installed):
$ make mandocs
# make installmandocs
// Now you can run:
man 9 printk
- For background chapter 14 of linux device drivers is a must read.
- Although this article is a little outdated. This how-to demonstrates much of what needs to be done.
- This kernel documentation is more up to date and should be read to see necessary changes from the greg kh linux journal article above.
- This is a sample driver for a usb keyboard.