Build the powerpc64 kernel as a position-independent executable. At s…

…tartup,

it processes its own ELF relocations and can be loaded and run in place at
any physical/virtual address.

NB: This requires an updated loader to boot!

Relnotes:	yes


git-svn-id: svn+ssh://svn.freebsd.org/base/head@277990 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f

UPDATING

@@ -31,6 +31,11 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 11.x IS SLOW:
 	disable the most expensive debugging functionality run
 	"ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+20150131:
+	The powerpc64 kernel has been changed to a position-independent
+	executable. This can only be booted with a new version of loader(8),
+	so make sure to update both world and kernel before rebooting.
+
 20150118:
 	Clang and llvm have been upgraded to 3.5.1 release.  This is a bugfix
 	only release, no new features have been added.  Please see the 20141231

sys/conf/Makefile.powerpc

@@ -37,6 +37,11 @@ INCLUDES+= -I$S/contrib/libfdt
 
 CFLAGS+= -msoft-float -Wa,-many
 
+.if ${MACHINE_ARCH} == "powerpc64"
+CFLAGS+= -fPIC
+LDFLAGS+= -pie
+.endif
+
 .if !empty(DDB_ENABLED)
 CFLAGS+=	-fno-omit-frame-pointer
 .endif