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Operating System Kernel Compilation

Operating System Kernel Compilation. Sarah Diesburg CS 3430 Operating Systems. Kernel Coding. The next project involves compiling a new kernel! Fun but challenging…. Each person/team will get their own virtual machine(s) See website instructions for how to install/use the virtual machine.

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Operating System Kernel Compilation

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  1. Operating System Kernel Compilation Sarah Diesburg CS 3430 Operating Systems

  2. Kernel Coding • The next project involves compiling a new kernel! • Fun but challenging…. • Each person/team will get their own virtual machine(s) • See website instructions for how to install/use the virtual machine

  3. Booting with the Bootloader (grub2) • The newest version of the kernel will boot by default • Look in the submenu (or further down the list) for any older version

  4. Logging In • Username: user • Password: user • Username: root • Password: iamr00t

  5. Communicating with your fresh virtual machine • Use the GUI • Select the terminal program from the bottom of the left shortcuts bar

  6. Communicating with your fresh virtual machine (other ways) • Use ssh • Log into the terminal, and issue /sbin/ifconfig to get the second IP address • Type the IP address directly into PuTTY • Transfer files • Must use Winscp or Filezilla with the IP address found above • Basically, communicate with it the same way you communicated with the student.cs.uni.edu machine

  7. SSH/WinSCP Demo… • Issue this command inside VM to get its IP address ip address

  8. If you created your own virtual machine…. • Good for you! • You will want to install these packages: • gcc / flex / bison • make • ssh • vim / emacs / (your choice of editor) • libssl-dev • libncurses5-dev • others (heh heh)

  9. Kernel Compilation

  10. Example of Kernel Compilation….

  11. Choosing a Kernel • The next project will involve kernel development • We all need to be in the same boat… • The class version will be 4.20.10 (bleeding edge stable version)

  12. Kernel Repository • http://kernel.org – place to download latest and greatest Linux kernels! • Traditional place for kernel is in /usr/src/ • It is already in there for you • …That is, unless you created your own virtual machine. Then download it from kernel.org, and extract it with the command • $> tar xv linux-4.20.10.tar.xz

  13. Compiling the Kernel • Compiles based on configuration of .config file located in the kernel source directory • How can I correctly configure my kernel? • Use the ‘make oldconfig’ command • Use the ‘make menuconfig’ command

  14. ‘make oldconfig’ • This command makes the default configuration file for Linux. • It creates a new configuration file based on the old configuration, so the kernel has the right mix of drivers

  15. ‘make menuconfig’ • Only do this if you are trying to make the kernel smaller • Manually select and deselect drivers and options for your kernel • * -- compiled directly into kernel • M – compiled into a module (driver) that can be dynamically added • Can be tough to figure out what you need and don’t need • Command ‘lspci’ shows hardware on computer

  16. ‘make menuconfig’

  17. ‘lspci’

  18. General Linux Source Organization • Memory Management • Networking Layer • Security • Sound Processing • Architecture-specific Code • Disk Drivers • Devices • File Systems

  19. Config Example (Inside Source Dir) $> cd /usr/src/linux-4.20.10 $> make oldconfig $> make menuconfig

  20. Compiling the Kernel • Issue ‘make’ inside the source directory $> make • Grab some coffee….

  21. Installing the Kernel • Install the modules (drivers) • $> make modules_install • Install the actual kernel • $> make install

  22. Historical final steps • Now the ‘make install’ command does all the following for you • Create a ramfs image • Update grub

  23. Boot Driver Problem • Why ramfs? • Suppose you compiled the disk drivers and root file system drivers as modules • Boot process loads the kernel image • Kernel image does not contain disk drivers

  24. Configure the Boot Loader (Grub) • Update bootloader (no longer necessary with ‘make install’) $> sudo update-grub • Now you can issue a reboot and cross your fingers! $> sudo reboot

  25. Telling Which Kernel You are In • Select the new kernel from the grub menu! • Watch your virtual machine • If something goes wrong, reboot and go back into your original kernel to try again • The following command will tell you which kernel you are in: $> uname -r

  26. Uh oh…. • If it doesn’t boot, go back into the original kernel • Always important to have one working kernel! • Make sure you didn’t skip a step… • You may have taken too much out of the kernel… • Start with bloated kernel, take things out one by one

  27. Project 2 Spec • Let’s take a look at it

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