Fix vboxsf host mounting.

vboxguest is included in 4.16, but not vboxsf.
I couldn't get vboxsf to compile for 4.16, so I downgraded to 4.15.

Makefile

@@ -169,6 +169,11 @@ else
 		$(ISO_BUILD_IMAGE) /usr/bin/make out/minikube.iso
 endif
 
+iso_in_docker:
+	docker run -it --rm --workdir /mnt --volume $(CURDIR):/mnt $(ISO_DOCKER_EXTRA_ARGS) \
+		--user $(shell id -u):$(shell id -g) --env HOME=/tmp --env IN_DOCKER=1 \
+		$(ISO_BUILD_IMAGE) /bin/bash
+
 test-iso:
 	go test -v $(REPOPATH)/test/integration --tags=iso --minikube-args="--iso-url=file://$(shell pwd)/out/buildroot/output/images/rootfs.iso9660"
 

deploy/iso/minikube-iso/configs/minikube_defconfig

@@ -3,6 +3,7 @@ BR2_CCACHE=y
 BR2_OPTIMIZE_2=y
 BR2_TOOLCHAIN_BUILDROOT_VENDOR="minikube"
 BR2_TOOLCHAIN_BUILDROOT_GLIBC=y
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_15=y
 BR2_BINUTILS_VERSION_2_30_X=y
 BR2_GCC_VERSION_7_X=y
 BR2_TOOLCHAIN_BUILDROOT_CXX=y
@@ -18,7 +19,7 @@ BR2_ROOTFS_USERS_TABLES="$(BR2_EXTERNAL_MINIKUBE_PATH)/board/coreos/minikube/use
 BR2_ROOTFS_OVERLAY="$(BR2_EXTERNAL_MINIKUBE_PATH)/board/coreos/minikube/rootfs-overlay"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.16.14"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.15"
 BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
 BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="$(BR2_EXTERNAL_MINIKUBE_PATH)/board/coreos/minikube/linux_defconfig"
 BR2_LINUX_KERNEL_NEEDS_HOST_LIBELF=y
@@ -31,6 +32,7 @@ BR2_PACKAGE_CIFS_UTILS=y
 BR2_PACKAGE_E2TOOLS=y
 BR2_PACKAGE_NFS_UTILS=y
 BR2_PACKAGE_SSHFS=y
+BR2_PACKAGE_XFSPROGS=y
 BR2_PACKAGE_PARTED=y
 BR2_PACKAGE_CA_CERTIFICATES=y
 BR2_PACKAGE_CURL=y
@@ -50,7 +52,6 @@ BR2_PACKAGE_SYSTEMD_LOGIND=y
 BR2_PACKAGE_SYSTEMD_MACHINED=y
 BR2_PACKAGE_SYSTEMD_VCONSOLE=y
 BR2_PACKAGE_UTIL_LINUX_NSENTER=y
-BR2_PACKAGE_XFSPROGS=y
 BR2_TARGET_ROOTFS_CPIO_BZIP2=y
 BR2_TARGET_ROOTFS_ISO9660=y
 BR2_TARGET_ROOTFS_ISO9660_BOOT_MENU="$(BR2_EXTERNAL_MINIKUBE_PATH)/board/coreos/minikube/isolinux.cfg"

deploy/iso/minikube-iso/package/Config.in

@@ -10,4 +10,5 @@ menu "System tools"
     source "$BR2_EXTERNAL_MINIKUBE_PATH/package/cni-plugins-bin/Config.in"
     source "$BR2_EXTERNAL_MINIKUBE_PATH/package/hv-kvp-daemon/Config.in"
     source "$BR2_EXTERNAL_MINIKUBE_PATH/package/gluster/Config.in"
+    source "$BR2_EXTERNAL_MINIKUBE_PATH/package/vbox-guest/Config.in"
 endmenu

deploy/iso/minikube-iso/package/vbox-guest/Config.in

@@ -0,0 +1,5 @@
+config BR2_PACKAGE_VBOX_GUEST
+	bool "vbox-guest"
+	default y
+	depends on BR2_LINUX_KERNEL
+

deploy/iso/minikube-iso/package/vbox-guest/vbox-guest.hash

@@ -0,0 +1,3 @@
+# From http://download.virtualbox.org/virtualbox/5.1.30/SHA256SUMS
+sha256 96cab2296fb014ce0a16b7b9603b52208b9403c10c1524b44201d3c274e8a821  VirtualBox-5.1.38.tar.bz2
+sha256 0e7ee2c78ebf7cd0d3a933d51148bef04a64f64fb27ccf70d59cddf9ca1e517a  VBoxGuestAdditions_5.1.38.iso

deploy/iso/minikube-iso/package/vbox-guest/vbox-guest.mk

@@ -0,0 +1,67 @@
+################################################################################
+#
+# VirtualBox Linux Guest Drivers
+#
+################################################################################
+
+VBOX_GUEST_VERSION = 5.1.38
+VBOX_GUEST_SITE = http://download.virtualbox.org/virtualbox/$(VBOX_GUEST_VERSION)
+VBOX_GUEST_LICENSE = GPLv2
+VBOX_GUEST_LICENSE_FILES = COPYING
+VBOX_GUEST_SOURCE = VirtualBox-$(VBOX_GUEST_VERSION).tar.bz2
+VBOX_GUEST_EXTRA_DOWNLOADS = http://download.virtualbox.org/virtualbox/${VBOX_GUEST_VERSION}/VBoxGuestAdditions_${VBOX_GUEST_VERSION}.iso
+
+define VBOX_GUEST_EXPORT_MODULES
+	( cd $(@D)/src/VBox/Additions/linux; ./export_modules modules.tar.gz )
+	mkdir -p $(@D)/vbox-modules
+	tar -C $(@D)/vbox-modules -xzf $(@D)/src/VBox/Additions/linux/modules.tar.gz
+endef
+
+VBOX_GUEST_POST_EXTRACT_HOOKS += VBOX_GUEST_EXPORT_MODULES
+
+VBOX_GUEST_MODULE_SUBDIRS = vbox-modules/
+VBOX_GUEST_MODULE_MAKE_OPTS = KVERSION=$(LINUX_VERSION_PROBED)
+
+define VBOX_GUEST_USERS
+	- -1 vboxsf -1 - - - - -
+endef
+
+define VBOX_GUEST_INSTALL_INIT_SYSTEMD
+	$(INSTALL) -D -m 644 \
+		$(BR2_EXTERNAL_MINIKUBE_PATH)/package/vbox-guest/vboxservice.service \
+		$(TARGET_DIR)/usr/lib/systemd/system/vboxservice.service
+
+	ln -fs /usr/lib/systemd/system/vboxservice.service \
+		$(TARGET_DIR)/etc/systemd/system/multi-user.target.wants/vboxservice.service
+endef
+
+define VBOX_GUEST_BUILD_CMDS
+	7z x -aoa $(BR2_DL_DIR)/vbox-guest/VBoxGuestAdditions_${VBOX_GUEST_VERSION}.iso -ir'!VBoxLinuxAdditions.run' -o"$(@D)"
+	sh $(@D)/VBoxLinuxAdditions.run --noexec --target $(@D)
+	tar --overwrite -C $(@D) -xjf $(@D)/VBoxGuestAdditions-amd64.tar.bz2 sbin/VBoxService
+	tar --overwrite -C $(@D) -xjf $(@D)/VBoxGuestAdditions-amd64.tar.bz2 bin/VBoxControl
+
+	$(TARGET_CC) -Wall -O2 -D_GNU_SOURCE -DIN_RING3 \
+		-I$(@D)/vbox-modules/vboxsf/include \
+		-I$(@D)/vbox-modules/vboxsf \
+		-o $(@D)/vbox-modules/mount.vboxsf \
+		$(@D)/src/VBox/Additions/linux/sharedfolders/vbsfmount.c \
+		$(@D)/src/VBox/Additions/linux/sharedfolders/mount.vboxsf.c
+endef
+
+define VBOX_GUEST_INSTALL_TARGET_CMDS
+	$(INSTALL) -Dm755 \
+		$(@D)/vbox-modules/mount.vboxsf \
+		$(TARGET_DIR)/sbin
+
+	$(INSTALL) -Dm755 \
+		$(@D)/sbin/VBoxService \
+		$(TARGET_DIR)/sbin
+
+	$(INSTALL) -Dm755 \
+		$(@D)/bin/VBoxControl \
+		$(TARGET_DIR)/bin
+endef
+
+$(eval $(kernel-module))
+$(eval $(generic-package))

deploy/iso/minikube-iso/package/vbox-guest/vboxservice.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=VirtualBox Guest Service
+ConditionVirtualization=oracle
+
+[Service]
+ExecStartPre=-/usr/sbin/modprobe vboxguest
+ExecStartPre=-/usr/sbin/modprobe vboxvideo
+ExecStartPre=-/usr/sbin/modprobe vboxsf
+ExecStart=/usr/sbin/VBoxService -f --disable-automount
+
+[Install]
+WantedBy=multi-user.target