Category: Programming

I apologize for the pause in posts. We moved over the weekend. Last Friday at&t told me that the new DSL was working at our new house. However, it did not actually start working outside the house until Wednesday. Then a problem with the internal wiring meant that it was not working inside the house…

Archives Archives are a traditional Unix package format. They are created by the ar program, and they are normally named with a .a extension. Archives are passed to a Unix linker with the -l option. Although the ar program is capable of creating an archive from any type of file, it is normally used to…

Parallel Linking It is possible to parallelize the linking process somewhat. This can help hide I/O latency and can take better advantage of modern multi-core systems. My intention with gold is to use these ideas to speed up the linking process. The first area which can be parallelized is reading the symbols and relocation entries…

Symbol Versions A shared library provides an API. Since executables are built with a specific set of header files and linked against a specific instance of the shared library, it also provides an ABI. It is desirable to be able to update the shared library independently of the executable. This permits fixing bugs in the…

ELF Segments Earlier I said that executable file formats were normally the same as object file formats. That is true for ELF, but with a twist. In ELF, object files are composed of sections: all the data in the file is accessed via the section table. Executables and shared libraries normally contain a section table,…