Decouple yarrow from random(4) device.

* Make Yarrow an optional kernel component -- enabled by "YARROW_RNG" option.
  The files sha2.c, hash.c, randomdev_soft.c and yarrow.c comprise yarrow.

* random(4) device doesn't really depend on rijndael-*.  Yarrow, however, does.

* Add random_adaptors.[ch] which is basically a store of random_adaptor's.
  random_adaptor is basically an adapter that plugs in to random(4).
  random_adaptor can only be plugged in to random(4) very early in bootup.
  Unplugging random_adaptor from random(4) is not supported, and is probably a
  bad idea anyway, due to potential loss of entropy pools.
  We currently have 3 random_adaptors:
  + yarrow
  + rdrand (ivy.c)
  + nehemeiah

* Remove platform dependent logic from probe.c, and move it into
  corresponding registration routines of each random_adaptor provider.
  probe.c doesn't do anything other than picking a specific random_adaptor
  from a list of registered ones.

* If the kernel doesn't have any random_adaptor adapters present then the
  creation of /dev/random is postponed until next random_adaptor is kldload'ed.

* Fix randomdev_soft.c to refer to its own random_adaptor, instead of a
  system wide one.

Submitted by: arthurmesh@gmail.com, obrien
Obtained from: Juniper Networks
Reviewed by: obrien

1 files changed, 10 insertions, 0 deletions

diff --git a/sys/modules/rdrand_rng/Makefile b/sys/modules/rdrand_rng/Makefile
new file mode 100644
index 000000000000..2cfd3fde599c
--- /dev/null
+++ b/sys/modules/rdrand_rng/Makefile
@@ -0,0 +1,10 @@
+# $FreeBSD$
+
+.PATH: ${.CURDIR}/../../dev/random
+
+KMOD=	rdrand_rng
+
+SRCS+=	\
+	ivy.c
+
+.include <bsd.kmod.mk>