simplifying the module linking process and eliminating the risks
associated with doubly-defined variables.
Cases where commons were legitimately used (detection of
compiled-in subsystems) have been converted to use sysinits, and
any new code should use this or an equivalent practice as a
matter of course.
Modules can override this behaviour by substituting -fno-common
out of ${CFLAGS} in cases where commons are necessary
(eg. third-party object modules). Commons will be resolved and
allocated space when the kld is linked as part of the module
build process, so they will not pose a risk to the kernel or
other modules.
Provide a mechanism for controlling the export of symbols from
the module namespace. The EXPORT_SYMS variable may be set in the
Makefile to NO (export no symbols), a list of symbols to export,
or the name of a file containing a newline-seperated list of
symbols to be exported. Non-exported symbols are converted to
local symbols. If EXPORT_SYMS is not set, all global symbols are
currently exported. This behaviour is expected to change (to
exporting no symbols) once modules have been converted.
Reviewed by: peter (in principle)
Obtained from: green (kmod_syms.awk)
