Add a comment to release/release.conf.sample documenting

EMBEDDEDPORTS. [1]

Remove and update stale documentation from release(7) while here.

PR:		206344 [1]
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation

2 files changed, 32 insertions, 26 deletions

diff --git a/release/release.conf.sample b/release/release.conf.sample
index 176894a08818..7c94d45b5307 100644
--- a/release/release.conf.sample
+++ b/release/release.conf.sample
@@ -61,6 +61,20 @@ PORTBRANCH="ports/head@rHEAD"
 ## Set when building embedded images.
 #EMBEDDEDBUILD=
 
+## Set to a list of ports required to build embedded system-on-chip
+## images, such as sysutils/u-boot-rpi.
+#EMBEDDEDPORTS=
+
+## Set to the hardware platform of the target userland.  This value
+## is passed to make(1) to set the TARGET (value of uname -m) to cross
+## build.
+#EMBEDDED_TARGET=
+
+## Set to the hardware platform of the target userland.  This value
+## is passed to make(1) to set the TARGET_ARCH (value of uname -p) to
+## cross build.
+#EMBEDDED_TARGET_ARCH=
+
 ## Set to skip the chroot environment buildworld/installworld/distribution
 ## step if it is expected the build environment will exist via alternate
 ## means.
diff --git a/share/man/man7/release.7 b/share/man/man7/release.7
index 065ef1037332..673f2a436d13 100644
--- a/share/man/man7/release.7
+++ b/share/man/man7/release.7
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd January 28, 2017
+.Dd November 28, 2017
 .Dt RELEASE 7
 .Os
 .Sh NAME
@@ -314,7 +314,6 @@ variables are relevant only to release builds for embedded systems:
 .It Va EMBEDDEDBUILD
 Set to a non-null value to enable functionality for embedded device
 release builds.
-.Pq This option is considered highly experimental.
 .Pp
 When set,
 .Va WITH_DVD
@@ -322,15 +321,15 @@ is unset, and
 .Va NODOC
 is defined.
 Additionally,
-.Va XDEV
+.Va EMBEDDED_TARGET
 and
-.Va XDEV_ARCH
+.Va EMBEDDED_TARGET_ARCH
 must also be defined.
 When the build environment is created,
 .Fa release.sh
 runs a separate build script located in an architecture-specific
 directory in
-.Pa src/release/${XDEV}/ .
+.Pa src/release/${EMBEDDED_TARGET}/ .
 .It Va EMBEDDEDPORTS
 Set to the list of any ports that are required for the target device
 in the format of
@@ -338,27 +337,20 @@ in the format of
 The
 .Fa devel/subversion
 port is built by default.
-.It Va CROCHETSRC
-Set to the source URL for the Crochet build tool.
-.It Va CROCHETBRANCH
-Set to the subversion branch from
-.Va ${CROCHETSRC}
-to use.
-Defaults to
-.Pa trunk .
-.It Va UBOOTSRC
-Set to the source URL of u-boot, if required.
-.It Va UBOOTBRANCH
-Set to the subversion branch from
-.Va ${UBOOTSRC}
-to use.
-Defaults to
-.Pa trunk .
-.It Va UBOOTDIR
-Set to the target directory within
-.Va ${CHROOTDIR}
-to check out
-.Va ${UBOOTSRC}/${UBOOTBRANCH} .
+.It Va EMBEDDED_TARGET
+When set, its value is passed to
+.Xr make 1
+to set the
+.Va TARGET
+.Pq value of Cm uname Fl m
+to cross build the target userland.
+.It Va EMBEDDED_TARGET_ARCH
+When set, its value is passed to
+.Xr make 1
+to set the
+.Va TARGET_ARCH
+.Pq value of Cm uname Fl p
+to cross build the target userland.
 .El
 .Sh VIRTUAL MACHINE DISK IMAGES
 The following