Merge the following from ^/projects/release-arm64 to allow

building FreeBSD/arm64 VM images and memstick.img installation
medium:
r281786, r281788, r281792:

 r281786:
  Add support for building arm64/aarch64 virtual machine images.

 r281788:
  Copy amd64/make-memstick.sh to arm64/make-memstick.sh for
  aarch64 memory stick images.

  Although arm64 does not yet have USB support, the memstick
  image should be bootable with certain virtualization tools,
  such as qemu.

 r281792:

  Add a buildenv_setup() prototype, intended to be overridden as
  needed.

  For example, the arm64/aarch64 build needs devel/aarch64-binutils,
  so buildenv_setup() in the release.conf for this architecture
  handles the installation of the port before buildworld/buildkernel.

Sponsored by:	The FreeBSD Foundation

release/arm64/make-memstick.sh

@@ -0,0 +1,41 @@
+#!/bin/sh
+#
+# This script generates a "memstick image" (image that can be copied to a
+# USB memory stick) from a directory tree.  Note that the script does not
+# clean up after itself very well for error conditions on purpose so the
+# problem can be diagnosed (full filesystem most likely but ...).
+#
+# Usage: make-memstick.sh <directory tree> <image filename>
+#
+# $FreeBSD$
+#
+
+PATH=/bin:/usr/bin:/sbin:/usr/sbin
+export PATH
+
+if [ $# -ne 2 ]; then
+	echo "make-memstick.sh /path/to/directory /path/to/image/file"
+	exit 1
+fi
+
+if [ ! -d ${1} ]; then
+	echo "${1} must be a directory"
+	exit 1
+fi
+
+if [ -e ${2} ]; then
+	echo "won't overwrite ${2}"
+	exit 1
+fi
+
+echo '/dev/ufs/FreeBSD_Install / ufs ro,noatime 1 1' > ${1}/etc/fstab
+makefs -B little -o label=FreeBSD_Install ${2}.part ${1}
+if [ $? -ne 0 ]; then
+	echo "makefs failed"
+	exit 1
+fi
+rm ${1}/etc/fstab
+
+mkimg -s gpt -p efi:=${1}/boot/boot1.efifat -p freebsd-boot:=${1}/boot/gptboot -p freebsd-ufs:=${2}.part -p freebsd-swap::1M -o ${2}
+rm ${2}.part
+

release/release.conf.sample

@@ -7,6 +7,7 @@
 ## defined in release.sh.
 #load_chroot_env() { }
 #load_target_env() { }
+#buildenv_setup() { }
 
 ## Set the directory within which the release will be built.
 CHROOTDIR="/scratch"

release/release.sh

@@ -42,6 +42,7 @@ export PATH
 # Prototypes that can be redefined per-chroot or per-target.
 load_chroot_env() { }
 load_target_env() { }
+buildenv_setup() { }
 
 # The directory within which the release will be built.
 CHROOTDIR="/scratch"
@@ -279,6 +280,7 @@ if [ -d ${CHROOTDIR}/usr/ports ]; then
 	fi
 fi
 
+buildenv_setup
 load_target_env
 eval chroot ${CHROOTDIR} make -C /usr/src ${RELEASE_WMAKEFLAGS} buildworld
 eval chroot ${CHROOTDIR} make -C /usr/src ${RELEASE_KMAKEFLAGS} buildkernel

release/tools/vmimage.subr

@@ -29,6 +29,13 @@ write_partition_layout() {
 				-p freebsd-ufs/rootfs:=${VMBASE} \
 				-o ${VMIMAGE}
 			;;
+		arm64:aarch64)
+			mkimg -s gpt \
+				-p efi/efiboot:=${BOOTFILES}/efi/boot1/boot1.efifat \
+				${SWAPOPT} \
+				-p freebsd-ufs/rootfs:=${VMBASE} \
+				-o ${VMIMAGE}
+			;;
 		powerpc:powerpc*)
 			mkimg -s apm \
 				-p apple-boot/bootfs:=${BOOTFILES}/powerpc/boot1.chrp/boot1.hfs \