Linker: Linker is a
program that takes one or more objects generated by a compiler and combines
them into a single executable program.
Linker is a program that takes one or more objects generated by a
compiler and combines them into a single executable program.
Once a linker has
scanned all of the input files to determine segment sizes, symbol definitions
and symbol references, figured out which library modules to include, and
decided where in the output address space all of the segments will go, the next
stage the heart of the linking process, relocation is. We use relocation to
refer both to the process of adjusting program addresses to account for
non-zero segment origins, and the process of resolving references to external
symbols, since the two are frequently handled together. The linker's first pass
lays out the positions of the various segments and collects the
segment-relative values of all global symbols in the program. Once the linker
determines the position of each segment, it potentially needs to fix up all
storage addresses to reflect the new locations of the segments. On most
architecture, addresses in data are absolute, while those embedded in
instructions may be absolute or relative. The linker needs to fix up
accordingly, as we'll discuss later
Loaders: Loader is the part of an operating system
that is responsible for loading programs from executable (i.e., executable
files) into memory, preparing them for execution and then executing them.
Loader is the part of an operating system that
is responsible for loading programs from executable (i.e., executable files)
into memory, preparing them for execution and then executing them. In computing, a loader is
the part of an operating system that is responsible for loading programs.
It is one of the essential stages in the process of starting a program, as it
places programs into memory and prepares them for execution. Loading a program
involves reading the contents of executable file, the file containing the program text, into
memory, and then carrying out other required preparatory tasks to prepare the
executable for running. Once loading is complete, the operating system starts
the program by passing control to the loaded program code.
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