The main tools in this class are an x86 emulator, called QEMU, and a compiler toolchain (including assembler, linker, loader, C compiler, debugger), which will produce code (often a small-scale operating system) that will run on top of QEMU. These tools are included on the platform on which you will do your lab work. You have two choices for this platform:
The choice is up to you; there is no right answer. Each option has advantages and disadvantages. The advantage to the first option is that the lab will run completely on your own computer (and does not require Internet access, provided that you have the lab description locally). A disadvantage is that you have to do a bit more setup (which we describe and walk through below). A second disadvantage is that you will be interacting with two layers of virtualization (the host of the devbox, and then QEMU); this could be confusing. (This could also harm performance, but that will not be a concern for most of the labs.) The second option is the other way around: after your account is set up, you have to do very little setup, and there will be only one layer of virtualization. The disadvantage to this option is that you will be interacting with a computer in a lab somewhere, which requires working over ssh (which in turn requires Internet access).
One way to ensure that we are all using a uniform development environment (short of us all using the same machine) is for us to use identically configured virtual machines. You can think of a virtual machine as a way to run a particular operating system (in our case, an Ubuntu desktop) on top of another operating system (the one that controls your laptop or desktop).
To get our virtual devbox running, you should do the following:
Notice the potential confusion from this arrangement. VirtualBox is creating a fake machine (with a fake x86 CPU). Ubuntu desktop is running on that fake machine (though neither Ubuntu desktop nor the applications (compiler, editor, browser) running on Ubuntu desktop are aware that they are running on a fake machine). The confusion enters because one of the applications that you are going to run on Ubuntu desktop is QEMU, and what does QEMU do? It creates another fake machine on which one can run an operating system. In our case, this fake machine will run the lab OSes (the mini operating systems and, perhaps, Linux). To recap: our lab OSes will run on the fake machine that QEMU provides, QEMU is running on Ubuntu desktop, Ubuntu desktop is the operating system for the fake machine that VirtualBox provides, and VirtualBox is running on your computer's operating system (known as the "host" operating system).
All of this is to say that there are actually two levels of virtualization in play. The two levels serve different purposes. The purpose of the lower is to create a uniform devbox. The purpose of the upper is to create the illusion of a physical machine so that you can develop, debug, and run the lab code. (This is a good example of how virtualization serves multiple purposes.)
A potentially interesting point is that although the two levels of virtualization serve different purposes, and although they are implemented with different software (VirtualBox and QEMU, respectively), they accomplish their function using similar technology. We discuss this technology in depth in advanced OS classes. In the meantime, welcome to The Matrix....
Even if you are not on campus, you can access CSIL machines remotely using ssh. We describe the steps below. Follow these steps:
For Linux and OS X users, open a terminal (xterm or via the Terminal program, etc), and type the following:
$ ssh -X [username]@csil-[machine-number].cs.ucsb.edu
In this command, [username] is your CSIL username, and [machine-number] is a number between 01 and 48. The parameter "-X" arranges for graphics painted by the programs you run remotely to show up on your local computer. If the parameter "-X" does not work for you, try the parameter "-Y" instead.
For Windows users, there are several ssh clients. A decent one is PuTTY. We will assume that you are going to use this software.
For all users, if you have successfully logged in, you will see a prompt similar to
You should also see your home directory.
You are now ready to begin the labs.
Last updated: 2020-03-27 23:14:16 -0700 [validate xhtml]