SPO600 Code Building Lab

Purpose of this Lab
In this lab, you will do a baseline build of a software package.

Lab 2

Prerequisites

You must have a working accounts on a Linux system (such as the SPO600 Servers or your own system).

Tasks

Do not build or install this software as the root user.
Do not build the software as root, and do not install the software into the system directories. Doing so may cause conflicts with other software on the system and/or may leave your system in an unusable state, and may be very difficult to reverse.

Build an open source software package

1. Select an open source software package from the Free Software Foundation's GNU Project or another open source project.
2. Download the source code for the software. (Do not install with dnf/yum!)
3. Build the software. You may need to install build dependencies (e.g., compilers, tools, and libraries); you can do this (and only this) as the root user using dnf/yum. For example, if you need cmake, run the command sudo dnf install cmake, and if you need the library ncurses, then run the command sudo dnf install ncurses-devel (the -devel specification will cause dnf to install the header files as well as the library, so that you can build software that uses that library).
4. Without installing the new software that you just built (because that could override the existing and working version), test that it works.
5. Blog your results. Explain (don't just document) each of the steps required to build your software and any dependencies you need to install. Include your reflections on the process.

Build and test glibc

Read the glibc Instructions
The glibc software and build system are complex, since this is core library which underlies most of the software on the system. Read the documentation carefully.

1. Find and build the source code for the latest released version of the GNU Standard C Library (glibc) -- see the instructions at https://sourceware.org/glibc/wiki/Testing/Builds. Note that glibc uses two parallel directory trees: one which contains the source code, and one which contains configuration and the output of the build system. You can safely delete all of the contents of the build directory and rebuild at any time.
2. Test the library which you have built (Critical: do this without installing it on your system and overwriting your existing glibc installation!). Prove that your version of the library is used in your tests by introducing a change in behaviour (for example, a small bug).
3. There are multiple implementations of some of the glibc functions: a basic version, written in C, and one or more versions optimized for various target architectures, in C or assembler (.s or .S files). Learn the mechanisms used to override one implementation with another -- read up on the override and multiarch system (don't just google "override" and "multiarch", because these have different meanings in different contexts! Research how those terms specifically apply to glibc).
4. Blog about the process, your results, your observations, and what you learned. Explain what glibc is and why it is important. Provide convincing proof that the version you tested is the specific version of glibc which you built. Explain the override and multiarch mechanisms.