SPARC GAS normally permits data to be misaligned. For example, it
permits the .long pseudo-op to be used on a byte boundary.
However, the native SunOS assemblers issue an error when they see
misaligned data.
You can use the --enforce-aligned-data option to make SPARC GAS
also issue an error about misaligned data, just as the SunOS
assemblers do.
The --enforce-aligned-data option is not the default because gcc
issues misaligned data pseudo-ops when it initializes certain packed
data structures (structures defined using the packed attribute).
You may have to assemble with GAS in order to initialize packed data
structures in your own code.