Project 0: Linux

1
Project 0 Linux Virtual Machine Dabbling

• CS-502, Operating Systems

2
In this project, we will

• Install our virtual machines and learn how to use
  them
• This is the place you will work during this
  course!
• Build and install the Linux kernel
• With your name on it!
• Follow Linux naming numbering conventions
• Turn in the project using web-based Turnin

3
In this project, we wont

• try to change anything in the kernel yet
• This is for next project
• try to support more than one machine
  architecture
• However, 32-bit and 64-bit architectures are
  different at the kernel level!
• Your virtual machine is not portable from one to
  the other

4
Installing your Virtual Machine Options

• Install from DVD using VMware Player or any other
  VMware product
• Needs 8 gigabytes of disk, 1-2 gigabytes of RAM,
  fast Pentium CPU (dual core would be very nice!)
• Use VMware Server on csopt4.wpi.edu
• Needs VMware client on your PC
• GUI interface to virtual machine
• Use Parallels on Macintosh (or other)
• See instructor

5
Installing from DVD

• See instructions on-line
• .doc, .html
• Download and install VMware Player
• Or other VMware product
• Unzip your virtual machine to new directory

6
Installing from DVD (continued)

• Choose type of networking
• Bridged vs. NAT (Network Address Translation)
• Start your virtual machine
• Fix up MAC address for network
• Boot OpenSUSE 10.2
• Login is as student, password CS-502
• Open YaST, the SUSE administration tool
• Fix and test networking
• Create new user identity for yourself
• Log out, log in as new identity, delete student

7
Using VMware Server on csopt4

• See instructions
• .doc, .html
• Get CS Department user ID and password
• Download and install VMware client
• Log onto csopt4, make new directory on
  /xtra_space drive
• Unzip the following file to your new directory
• /xtra_space/CS-502/CS-502_Fall-07_x86_64.zip

8
Using VMware Server on csopt4 (continued)

• Start VMware client, log into csopt4
• Browse to and open your virtual machine
• Rename it to something unique (your user ID)
• Set permissions
• Start your virtual machine
• Follow instructions for distributed version
• Networking, user identity, etc.

9
Setting OpenSUSE Linux 10.2 on Parallels

• See instructor
• Will install OpenSUSE Linux 10.2 directly to disk
  partition
• Be sure to get on-line updates
• Best to create a separate partition for /home
  directory
• Need to move /usr/src to /home/src
• Create link /usr/src ? /home/src

10
Questions?
11
To get started with kernel

• Find kernel sources in /usr/src, i.e., a link to
  /home/src
• linux-2.6.18.2-34linux-2.6.18.8-0.5
• Clone kernel source tree by linked copy
• In a terminal window, do
• cp al /usr/src/linux-2.6.18.8-0.5 kernelSrc
• Creates a linked copy of original tree in new
  directory called kernelSrc

12
Digression on Unix/Linux Hard Links

• Directory entries point directly to files
• Two entries may point to same file!
• Same or different directories
• Same or different name
• Permissions attached to file, not directory
• Called hard links (as opposed to symbolic links)
• Modifications to file seen via all hard links
• mv and rm commands change directories, not files!
• File goes away when all directory entries (i.e.,
  hard links) to that file are deleted.

13
Cloned Source Tree

• All directories are copied
• All directory entries in copy are hard-linked
  back to files in original source tree
• I.e., only one copy of each file exists
• To modify a file
• Unlink it (via mv or rm)
• Replace it with modified copy in your directory
• Original is preserved intact in original directory

14
To Modify a File

• mv file.c file.c
• Edit file.c in your favorite editor
• Save as file.c
• (Eventually) delete file.c
• EMACS and patch do this automatically
• Most other editors require you to do it manually

15
To Build Linux Kernel

• Make configuration step
• As ordinary user
• Build kernel files and modules
• As ordinary user
• Install modules, boot file, etc.
• Need root privileges

16
To Build Linux Kernel (continued)

• Always build to a separate destination tree
• mkdir /kernelDst
• make O/kernelDst
• Reason
• Making the configuration generates a lot of
  include files and other sources
• If you dont specify a destination, it fills up
  your source tree
• Your patch files grow to gt 1 megabyte!

17
Make configuration

• In a command shell
• cd kernelSrc
• Do one of
• make O/kernelDst config
• Very long and tedious
• make O/kernelDst menuconfig
• Still somewhat long and tedious also hokey
• make O/kernelDst xconfig
• Nice a GUI with very small print
• make O/kernelDst gconfig
• Really nice a better GUI highly recommended

18
Make configuration (continued)

• Edit General Setup to name your Local version
• No other edits necessary for this project.
• Save and quit
• If need to rebuild, use
• make O/kernelDst oldconfig
• to reuse same configuration

19
To Build Kernel

• In a terminal window (i.e., a shell), do
• cd kernelSrc
• make O/kernelDst
• Takes
• 20 minutes on dual-core 2.4 GHz Pentium, 2 GByte
• 40 minutes on csopt4 (last year)
• Almost two hours on 3 gigahertz Pentium, 1 GByte
• Rebuilds after small edits are much faster
• Changing .h files can cause longer rebuilds

20
One little glitch

• File include2/asm/asm-offsets.h not generated by
  make config
• Build crashes within about 2-3 minutes
• Link file from
• /kernelDst/include/asm-i386/ or
• /kernelDst/include/asm-x86_64
• to
• kernelDst/include2/asm
• Run make O/kernelDst again
• Without trying to remake the config
• Build should complete without further errors

21
For Project Submission

• Redirect build output to a file
• Submit that file (this project only)
• Note that there are lots of warnings in the Linux
  kernel
• Not your problem!

22
To Build Kernel on a Dual Processor

• Generally faster to do
• cd kernelSrc
• make j2 O/kernelDst
• Sometimes, this is even faster
• make j4 O/kernelDst
• SUSE advice
• 2 ? number of processors

23
To Install Kernel

• Requires root privileges
• sudo make modules_install install
• Note order of arguments!
• Puts kernel, initrd file, symbols in /boot
• Changes links for vmlinuz, initrd
• Adds entries to /boot/grub/menu.lst
• So your kernel shows up on boot screen
• So you can select which kernel to boot

24
Running Your Kernel

• Restart your virtual machine
• Click in boot window
• Use arrow keys to select desired kernel or system
• To determine which kernel is running
• uname -a

25
Submitting your Project

• From within your virtual machine, visit
• http//turnin.cs.wpi.edu8088/servlets/turnin.ss
• Log in
• Submit output of your build as Project 0
• This is to test the ability to submit projects
  from the virtual machine!

26
Questions?