[src/trunk]: src/usr.bin/config Revise a plan about link-set.

[uebayasi <uebayasi%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/15b00324df34
branches:  trunk
changeset: 333674:15b00324df34
user:      uebayasi <uebayasi%NetBSD.org@localhost>
date:      Thu Nov 13 15:25:48 2014 +0000

description:
Revise a plan about link-set.

(I was ignorant 2 weeks ago.)

diffstat:

 usr.bin/config/TODO |  22 +++++++++++++---------
 1 files changed, 13 insertions(+), 9 deletions(-)

diffs (34 lines):

diff -r c690ada4cc00 -r 15b00324df34 usr.bin/config/TODO
--- a/usr.bin/config/TODO       Thu Nov 13 15:03:06 2014 +0000
+++ b/usr.bin/config/TODO       Thu Nov 13 15:25:48 2014 +0000
@@ -158,17 +158,21 @@
   sequence of various subsystem initializations in init_main.c:main() will be
   replaced by an array of .kctors invocations, and #ifdef's there will be gone.
 
-o Replace linkset.
+o Hide link-set in the final kernel.
+
+  Link-set is used to collect references (pointers) at link time.  It relys on
+  the ld(1) behavior that it automatically generates `__start_X' and `__stop_X'
+  symbols for the section `X' to reduce coding.
+
+  Don't allow kernel subsystems create random ELF sections.
 
-  Don't allow kernel subsystems create random ELF sections (with potentially
-  long names) in the final kernel.  To collect some data in statically linked
-  modules, creating intermediate sections (e.g. .data.linkset.sysctl) and
-  exporting the start/end symbols (e.g. _data_linkset_sysctl_{start,end})
-  using linker script should be fine.
+  Pre-define all the available link-set names and pre-generate a linker script
+  to merge them into .rodata.
 
-  Dynamically loaded modules have to register those entries via constructors
-  (functions).  This means that dynamically loaded modules are flexible but
-  come with overhead.
+  (For modular(9) modules, `link_set_modules' is looked up by kernel loader.
+  Provide only it.)
+
+  Provide a way for 3rd party modules to declare extra link-set.
 
 o Shared kernel objects.