From cd9142c7185b26d9657fa0ea2e8c198e026bdd92 Mon Sep 17 00:00:00 2001
From: Warner Losh <imp@FreeBSD.org>
Date: Fri, 27 Mar 2015 17:36:22 +0000
Subject: [PATCH] Add a note of clarification. MK_* variables only control what
 modules are built by default. You can still override that with MODULES_EXTRA
 for experimental features like ZFS and dtrace on some architectures. Also
 note that kernel config files are not affected by MK_ options listed, though
 some targets might be.

---
 sys/conf/kern.opts.mk | 42 ++++--------------------------------------
 1 file changed, 4 insertions(+), 38 deletions(-)

diff --git a/sys/conf/kern.opts.mk b/sys/conf/kern.opts.mk
index 7da738a0785..f94ffb7595e 100644
--- a/sys/conf/kern.opts.mk
+++ b/sys/conf/kern.opts.mk
@@ -51,6 +51,10 @@ __DEFAULT_NO_OPTIONS = \
 # Some options are totally broken on some architectures. We disable
 # them. If you need to enable them on an experimental basis, you
 # must change this code.
+# Note: These only apply to the list of modules we build by default
+# and sometimes what is in the opt_*.h files by default.
+# Kernel config files are unaffected, though some targets can be
+# affected by KERNEL_SYMBOLS, FORMAT_EXTENSIONS, CTF and SSP.
 
 # Things that don't work based on the CPU
 .if ${MACHINE_CPUARCH} == "arm"
@@ -75,34 +79,6 @@ BROKEN_OPTIONS+= EISA
 BROKEN_OPTIONS+= OFED
 .endif
 
-# Options that cannot be turned on this architecture, usually because
-# of compilation or other issues so severe it cannot be used even
-# on an experimental basis
-__ALWAYS_NO_OPTIONS=
-
-# Things that don't work based on the CPU
-.if ${MACHINE_CPUARCH} == "arm"
-__ALWAYS_NO_OPTIONS+= CDDL ZFS
-.endif
-
-.if ${MACHINE_CPUARCH} == "mips"
-__ALWAYS_NO_OPTIONS+= CDDL ZFS
-.endif
-
-.if ${MACHINE_CPUARCH} == "powerpc" && ${MACHINE_ARCH} != "powerpc64"
-__ALWAYS_NO_OPTIONS+= ZFS
-.endif
-
-# Things that don't work because the kernel doesn't have the support
-# for them.
-.if ${MACHINE} != "i386"
-__ALWAYS_NO_OPTIONS+= EISA
-.endif
-
-.if ${MACHINE} != "i386" && ${MACHINE} != "amd64"
-__ALWAYS_NO_OPTIONS+= OFED
-.endif
-
 # expanded inline from bsd.mkopt.mk to avoid share/mk dependency
 
 # Those that default to yes
@@ -147,16 +123,6 @@ MK_${var}:=	no
 .undef BROKEN_OPTIONS
 #end of bsd.mkopt.mk expanded inline.
 
-#
-# MK_* options which are always no, usually because they are
-# unsupported/badly broken on this architecture.
-#
-.for var in ${__ALWAYS_NO_OPTIONS}
-MK_${var}:=	no
-.endfor
-.undef __ALWAYS_NO_OPTIONS
-#end of bsd.mkopt.mk expanded inline.
-
 #
 # MK_*_SUPPORT options which default to "yes" unless their corresponding
 # MK_* variable is set to "no".