Replace the a.out emulation of 'struct linker_set' with something
a little more flexible. <sys/linker_set.h> now provides macros for
accessing elements and completely hides the implementation.
The linker_set.h macros have been on the back burner in various
forms since 1998 and has ideas and code from Mike Smith (SET_FOREACH()),
John Polstra (ELF clue) and myself (cleaned up API and the conversion
of the rest of the kernel to use it).
The macros declare a strongly typed set. They return elements with the
type that you declare the set with, rather than a generic void *.
For ELF, we use the magic ld symbols (__start_<setname> and
__stop_<setname>). Thanks to Richard Henderson <rth@redhat.com> for the
trick about how to force ld to provide them for kld's.
For a.out, we use the old linker_set struct.
NOTE: the item lists are no longer null terminated. This is why
the code impact is high in certain areas.
The runtime linker has a new method to find the linker set
boundaries depending on which backend format is in use.
linker sets are still module/kld unfriendly and should never be used
for anything that may be modular one day.
Reviewed by: eivind
declarations will not be aligned by default.
o Remove the alignment work-around for alpha. Our current alpha
as(1) does not assume alignment after section switching, nor
does the ia64 as(1).
sysinits, for example, are sorted by swapping those objects(!). Perhaps
they should be const and the sysinit sorting should be swapping the
pointers rather than the targets. This is on my revisit list, but it
has the side effect of removing a lot of warnings. With -Wcast-qual, it
doesn't seem easy to get rid of the constness when you *know* it's not.
(With apologies to bde, this essentially reverts rev 1.21 of kernel.h
from back in 1996)
