The BSD Family
In this section we are going to take a quick look at the BSD
world. The operating systems considered are FreeBSD, NetBSD, OpenBSD
and Darwin. All the systems have support for kernel modules but
their use in NetBSD and OpenBSD is limited.
The "over time" term is used here to refer to releases. Timelines
for all the systems except Darwin are presented
Map of the external symbols for FreeBSD 7.2.
As before, each tick represents an external symbol. The horizontal
axis contains 832 symbols. The 26 .ko
modules related to
file systems were taken from the boot/kernel
the bootonly install CD. The FFS, the native filesystem for
FreeBSD, is not compiled as module so it doesn't show up here.
Exported symbols over time for FreeBSD.
Because the compiled kernel is readily available, an easy thing
to do is to look how the number of exported symbols changed over
time. Note that this plot starts with FreeBSD 4.5, the first
release for which symbols were not stripped from the kernel.
Exported symbols over time for NetBSD.
Unlike FreeBSD, in NetBSD there are significant, usually increase,
in the number of symbols from one major release to another. The
plot starts from 1.5 because that was the first one being compiled