linux layer cons

cons of layer isolation in os architecture

A modularized approach
Because any module can be linked and unlinked at runtime, system program-
mers must introduce well-defined software interfaces to access the data struc-
tures handled by modules. This makes it easy to develop new modules.
Platform independence
Even if it may rely on some specific hardware features, a module doesn’t depend
on a fixed hardware platform. For example, a disk driver module that relies on
the SCSI standard works as well on an IBM-compatible PC as it does on
Hewlett-Packard’s Alpha.
Frugal main memory usage
A module can be linked to the running kernel when its functionality is required
and unlinked when it is no longer useful; this is quite useful for small embedded
systems.
No performance penalty
Once linked in, the object code of a module is equivalent to the object code of
the statically linked kernel. Therefore, no explicit message passing is required
when the functions of the module are invoked.