10 COFF output module

This chapter describes the coff output module which can be selected with the ‘-Fcoff’ option.

10.1 Legal

This module is written in 2025 by Jean-Paul Mari and is covered by the vasm copyright without modifications.

10.2 Additional options for this module

‘-fmagic=<magic id>’

Sets the magic field of the coff header to an unsigned 16 bits value. The magic default is based on the CPU= define used.

10.3 General

This output module emits the coff (assembler output) format, which is a format for executable, object code, and shared library computer files used on Unix like systems. It was introduced in Unix System V, replaced the previously used a.out format.

10.4 Restrictions

The coff output format, as implemented in vasm, currently supports the following architectures:

• - arm
• - m68k
• - ppc
• - x86

10.5 Known Problems

Some known problems of this module at the moment:

• - The debug information is not supported.
• - The section’s names must fit on 8 characters.
• - The BSS section is saved in the object file.

10.6 Error Messages

This module has the following error messages:

• - 3002: output module doesn’t support cpu %s
• - 3005: reloc type <m>, size <n>, mask <mask> (symbol <sym> + <offset>) not supported