system: add support for merged-bin (branch yem/merged-bin)

index da9e20a35c..1bc8b61f11 100644
@@ -337,7 +337,7 @@ config BR2_ROOTFS_DEVICE_TABLE_SUPPORTS_EXTENDED_ATTRIBUTES
 	  Support extended attributes handling in device tables
 
 config BR2_ROOTFS_MERGED_USR
-	bool "Use symlinks to /usr for /bin, /sbin and /lib"
+	bool "Merged /usr"
 	help
 	  If you say 'n' here, then /bin, /sbin and /lib and their
 	  counterparts in /usr will be separate directories. This

index 1bc8b61f11..b24004c533 100644
@@ -535,7 +535,7 @@ endif # BR2_ROOTFS_SKELETON_DEFAULT
 config BR2_SYSTEM_DEFAULT_PATH
 	string "Set the system's default PATH"
 	default "/usr/bin:/usr/sbin" if BR2_ROOTFS_MERGED_USR
-	default "/bin:/sbin:/usr/bin:/usr/sbin" if !BR2_ROOTFS_MERGED_USR
+	default "/bin:/sbin:/usr/bin:/usr/sbin"
 	help
 	  Sets the system's default PATH. It is being used in
 	  /etc/profile in the skeleton-init-common package and by some

index 320d416203..0cb10ea3d8 100644
@@ -24,6 +24,7 @@ menuconfig BR2_PACKAGE_SYSTEMD
 	depends on BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_15
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_8
 	depends on BR2_HOST_GCC_AT_LEAST_8 # host-systemd
+	select BR2_ROOTFS_MERGED_USR
 	select BR2_PACKAGE_HAS_UDEV
 	select BR2_PACKAGE_DBUS if !BR2_PACKAGE_DBUS_BROKER # runtime
 	select BR2_PACKAGE_LIBCAP

index b24004c533..32462241a5 100644
@@ -115,10 +115,6 @@ comment "openrc needs a glibc or musl toolchain w/ dynamic library"
 	depends on BR2_USE_MMU
 	depends on BR2_STATIC_LIBS && BR2_TOOLCHAIN_USES_UCLIBC
 
-# In Buildroot, we decided not to support a split-usr when systemd is
-# used as an init system. This is a design decision, not a systemd
-# issue. Thus the select is with BR2_INIT_SYSTEMD (below) rather than
-# with BR2_PACKAGE_SYSTEMD.
 config BR2_INIT_SYSTEMD
 	bool "systemd"
 	depends on BR2_PACKAGE_SYSTEMD_ARCH_SUPPORTS

@@ -130,7 +126,6 @@ config BR2_INIT_SYSTEMD
 	depends on BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_15
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_8
 	depends on BR2_HOST_GCC_AT_LEAST_8
-	select BR2_ROOTFS_MERGED_USR
 	select BR2_PACKAGE_SYSTEMD
 	select BR2_PACKAGE_SKELETON_INIT_SYSTEMD if BR2_ROOTFS_SKELETON_DEFAULT
 

index 433857cd8c..ed0c58e9b7 100755
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env bash
 #
 # Check if a given custom skeleton or overlay complies to the merged /usr
 # requirements:

@@ -10,30 +10,36 @@
 # /usr/lib/
 # /usr/sbin/
 #
-# Output: the list of non-compliant paths (empty if compliant).
+# Input:
+#   $1:     the root directory (skeleton, overlay) to check
+# Output:
+#   stdout: the list of non-compliant paths (empty if compliant).
 #
 
+# The directory to check for merged-usr
+root="${1}"
+
 # Extract the inode numbers for all of those directories. In case any is
 # a symlink, we want to get the inode of the pointed-to directory, so we
 # append '/.' to be sure we get the target directory. Since the symlinks
 # can be anyway (/bin -> /usr/bin or /usr/bin -> /bin), we do that for
-# all of them.
+# each of them.
 #
-lib_inode=$(stat -c '%i' "${1}/lib/." 2>/dev/null)
-bin_inode=$(stat -c '%i' "${1}/bin/." 2>/dev/null)
-sbin_inode=$(stat -c '%i' "${1}/sbin/." 2>/dev/null)
-usr_lib_inode=$(stat -c '%i' "${1}/usr/lib/." 2>/dev/null)
-usr_bin_inode=$(stat -c '%i' "${1}/usr/bin/." 2>/dev/null)
-usr_sbin_inode=$(stat -c '%i' "${1}/usr/sbin/." 2>/dev/null)
 
-not_merged_dirs=""
-test -z "$lib_inode" || \
-	test "$lib_inode" = "$usr_lib_inode" || \
-		not_merged_dirs="/lib"
-test -z "$bin_inode" || \
-	test "$bin_inode" = "$usr_bin_inode" || \
-		not_merged_dirs="$not_merged_dirs /bin"
-test -z "$sbin_inode" || \
-	test "$sbin_inode" = "$usr_sbin_inode" || \
-		not_merged_dirs="$not_merged_dirs /sbin"
-echo "${not_merged_dirs# }"
+test_merged() {
+	local root="${1}"
+	local dir1="${2}"
+	local dir2="${3}"
+	local inode1 inode2
+
+	inode1="$(stat -c '%i' "${root}${dir1}/." 2>/dev/null)"
+	inode2="$(stat -c '%i' "${root}${dir2}/." 2>/dev/null)"
+
+	test -z "${inode1}" || \
+		test "${inode1}" = "${inode2}" || \
+			printf '%s\n' "${dir1}"
+}
+
+test_merged "${root}" "/lib" "/usr/lib"
+test_merged "${root}" "/bin" "/usr/bin"
+test_merged "${root}" "/sbin" "/usr/sbin"

index ed0c58e9b7..ac676185dd 100755
@@ -26,7 +26,7 @@ root="${1}"
 # each of them.
 #
 
-test_merged() {
+is_valid_merged() {
 	local root="${1}"
 	local dir1="${2}"
 	local dir2="${3}"

@@ -35,9 +35,17 @@ test_merged() {
 	inode1="$(stat -c '%i' "${root}${dir1}/." 2>/dev/null)"
 	inode2="$(stat -c '%i' "${root}${dir2}/." 2>/dev/null)"
 
-	test -z "${inode1}" || \
-		test "${inode1}" = "${inode2}" || \
-			printf '%s\n' "${dir1}"
+	test -z "${inode1}" || test "${inode1}" = "${inode2}"
+}
+
+test_merged() {
+	local root="${1}"
+	local dir1="${2}"
+	local dir2="${3}"
+
+	if ! is_valid_merged "${root}" "${dir1}" "${dir2}"; then
+		printf '%s\n' "${dir1}"
+	fi
 }
 
 test_merged "${root}" "/lib" "/usr/lib"

index ac676185dd..6d31c81c21 100755
@@ -14,6 +14,9 @@
 #   $1:     the root directory (skeleton, overlay) to check
 # Output:
 #   stdout: the list of non-compliant paths (empty if compliant).
+# Exit code:
+#   0:      in case of success (stdout will be empty)
+#   !0:     if any path is improperly merged
 #
 
 # The directory to check for merged-usr

@@ -45,9 +48,13 @@ test_merged() {
 
 	if ! is_valid_merged "${root}" "${dir1}" "${dir2}"; then
 		printf '%s\n' "${dir1}"
+		is_success=false
 	fi
 }
 
+is_success=true
 test_merged "${root}" "/lib" "/usr/lib"
 test_merged "${root}" "/bin" "/usr/bin"
 test_merged "${root}" "/sbin" "/usr/sbin"
+
+${is_success}

index d4ad4629c0..a74fcc7324 100644
@@ -782,17 +782,10 @@ endif
 # For a merged /usr, ensure that /lib, /bin and /sbin and their /usr
 # counterparts are appropriately setup as symlinks ones to the others.
 ifeq ($(BR2_ROOTFS_MERGED_USR),y)
-
-	$(foreach d, $(call qstrip,$(BR2_ROOTFS_OVERLAY)), \
-		@$(call MESSAGE,"Sanity check in overlay $(d)")$(sep) \
-		$(Q)not_merged_dirs="$$(support/scripts/check-merged-usr.sh $(d))"; \
-		test -n "$$not_merged_dirs" && { \
-			echo "ERROR: The overlay in $(d) is not" \
-				"using a merged /usr for the following directories:" \
-				$$not_merged_dirs; \
-			exit 1; \
-		} || true$(sep))
-
+	@$(call MESSAGE,"Sanity check in overlays $(call qstrip,$(BR2_ROOTFS_OVERLAY))")
+	support/scripts/check-merged-usr.sh \
+		--type overlay \
+		$(call qstrip,$(BR2_ROOTFS_OVERLAY))
 endif # merged /usr
 
 	$(foreach d, $(call qstrip,$(BR2_ROOTFS_OVERLAY)), \

index b05c834b94..c194108307 100644
@@ -26,17 +26,16 @@ endif
 # For a merged /usr, ensure that /lib, /bin and /sbin and their /usr
 # counterparts are appropriately setup as symlinks ones to the others.
 ifeq ($(BR2_ROOTFS_MERGED_USR),y)
-SKELETON_CUSTOM_NOT_MERGED_USR_DIRS = \
-	$(shell support/scripts/check-merged-usr.sh $(SKELETON_CUSTOM_PATH))
+define SKELETON_CUSTOM_NOT_MERGED_USR_DIRS
+	support/scripts/check-merged-usr.sh \
+		--type skeleton \
+		$(SKELETON_CUSTOM_PATH)
+endef
 endif # merged /usr
 
-ifeq ($(BR2_PACKAGE_SKELETON_CUSTOM)$(BR_BUILDING),yy)
-ifneq ($(SKELETON_CUSTOM_NOT_MERGED_USR_DIRS),)
-$(error The custom skeleton in $(SKELETON_CUSTOM_PATH) is not \
-	using a merged /usr for the following directories: \
-	$(SKELETON_CUSTOM_NOT_MERGED_USR_DIRS))
-endif
-endif
+define SKELETON_CUSTOM_CONFIGURE_CMDS
+	$(SKELETON_CUSTOM_NOT_MERGED_USR_DIRS)
+endef
 
 # The target-dir-warning file and the lib{32,64} symlinks are the only
 # things we customise in the custom skeleton.

@@ -49,9 +48,7 @@ define SKELETON_CUSTOM_INSTALL_TARGET_CMDS
 endef
 
 # For the staging dir, we don't really care what we install, but we
-# need the /lib and /usr/lib appropriately setup. Since we ensure,
-# above, that they are correct in the skeleton, we can simply copy the
-# skeleton to staging.
+# need the /lib and /usr/lib appropriately setup.
 define SKELETON_CUSTOM_INSTALL_STAGING_CMDS
 	$(call SYSTEM_RSYNC,$(SKELETON_CUSTOM_PATH),$(STAGING_DIR))
 	$(call SYSTEM_USR_SYMLINKS_OR_DIRS,$(STAGING_DIR))

86 lines not on this page · raw message

index c3b5c6419a..34e726b4fb 100755
@@ -2,13 +2,14 @@
 #
 # Check if a given custom skeleton or overlay complies to the merged /usr
 # requirements:
-# /
-# /bin -> usr/bin
-# /lib -> usr/lib
-# /sbin -> usr/sbin
-# /usr/bin/
-# /usr/lib/
-# /usr/sbin/
+#   /bin            missing, or a relative symlink to usr/bin
+#   /lib            missing, or a relative symlink to usr/lib
+#   /sbin           missing, or a relative symlink to usr/sbin
+#   /usr/bin/       missing*, or an existing directory; not a symlink
+#   /usr/lib/       missing*, or an existing directory; not a symlink
+#   /usr/sbin/      missing*, or an existing directory; not a symlink
+#
+# *: must be present for skeletons, can be missing for overlays
 #
 # Input:
 #   --type TYPE     the type of root to check: 'skeleton' or 'overlay'

@@ -17,7 +18,7 @@
 #   stdout:         the list of non-compliant paths (empty if compliant).
 # Exit code:
 #   0:              in case of success (stdout will be empty)
-#   !0:             if any path is improperly merged
+#   !0:             if any directory to check is improperly merged
 #
 
 opts="type:"

@@ -38,6 +39,12 @@ while :; do
 	esac
 done
 
+if [ "${type}" = "skeleton" ]; then
+	strict=true
+else
+	strict=false
+fi
+
 report_error() {
 	local type="${1}"
 	local root="${2}"

@@ -54,44 +61,52 @@ report_error() {
 	is_success=false
 }
 
-# Extract the inode numbers for all of those directories. In case any is
-# a symlink, we want to get the inode of the pointed-to directory, so we
-# append '/.' to be sure we get the target directory. Since the symlinks
-# can be anyway (/bin -> /usr/bin or /usr/bin -> /bin), we do that for
-# each of them.
-#
-
-is_valid_merged() {
-	local root="${1}"
-	local dir1="${2}"
-	local dir2="${3}"
-	local inode1 inode2
-
-	inode1="$(stat -c '%i' "${root}${dir1}/." 2>/dev/null)"
-	inode2="$(stat -c '%i' "${root}${dir2}/." 2>/dev/null)"
-
-	test -z "${inode1}" || test "${inode1}" = "${inode2}"
-}
-
 test_merged() {
 	local type="${1}"
 	local root="${2}"
-	local dir1="${3}"
-	local dir2="${4}"
+	local base="${3}"
+	local dir1="${4}"
+	local dir2="${5}"
 
-	if ! is_valid_merged "${root}" "${dir1}" "${dir2}"; then
-		report_error "${type}" "${root}" \
-			'%s should be missing, or be a relative symlink to %s\n' \
-			"${dir1}" "${dir2}"
+	if ! test -e "${root}${base}${dir1}"; then
+		return 0
+	elif [ "$(readlink "${root}${base}${dir1}")" = "${dir2}" ]; then
+		return 0
 	fi
+
+	# Otherwise, this directory is not merged
+	report_error "${type}" "${root}" \
+		'%s%s should be missing, or be a relative symlink to %s\n' \
+		"${base}" "${dir1}" "${dir2}"
+}
+
+test_dir() {
+	local type="${1}"
+	local root="${2}"
+	local base="${3}"
+	local dir="${4}"
+
+	if ! test -e "${root}${base}${dir}" && ! ${strict}; then
+		return 0
+	elif test -d "${root}${base}${dir}" && ! test -L "${root}${base}${dir}"; then
+		return 0
+	fi
+
+	# Otherwise, this entry is not a proper directory
+	report_error "${type}" "${root}" \
+		"%s%s should exist, be a directory, and not be a symlink\n" \
+		"${base}" "${dir}"
 }
 
 is_success=true
 for root; do
 	first=true
-	test_merged "${type}" "${root}" "/lib" "/usr/lib"
-	test_merged "${type}" "${root}" "/bin" "/usr/bin"
-	test_merged "${type}" "${root}" "/sbin" "/usr/sbin"
+	test_dir "${type}" "${root}" "/" "usr/bin"
+	test_dir "${type}" "${root}" "/" "usr/lib"
+	test_dir "${type}" "${root}" "/" "usr/sbin"
+	test_merged "${type}" "${root}" "/" "bin" "usr/bin"
+	test_merged "${type}" "${root}" "/" "lib" "usr/lib"
+	test_merged "${type}" "${root}" "/" "sbin" "usr/sbin"
 done
 
 ${is_success}

index a74fcc7324..5a60e71d32 100644
@@ -783,7 +783,7 @@ endif
 # counterparts are appropriately setup as symlinks ones to the others.
 ifeq ($(BR2_ROOTFS_MERGED_USR),y)
 	@$(call MESSAGE,"Sanity check in overlays $(call qstrip,$(BR2_ROOTFS_OVERLAY))")
-	support/scripts/check-merged-usr.sh \
+	support/scripts/check-merged \
 		--type overlay \
 		$(call qstrip,$(BR2_ROOTFS_OVERLAY))
 endif # merged /usr

index c194108307..82e1506156 100644
@@ -27,7 +27,7 @@ endif
 # counterparts are appropriately setup as symlinks ones to the others.
 ifeq ($(BR2_ROOTFS_MERGED_USR),y)
 define SKELETON_CUSTOM_NOT_MERGED_USR_DIRS
-	support/scripts/check-merged-usr.sh \
+	support/scripts/check-merged \
 		--type skeleton \
 		$(SKELETON_CUSTOM_PATH)
 endef

similarity index 100%
rename from support/scripts/check-merged-usr.sh
rename to support/scripts/check-merged

index 5a60e71d32..2ff944f6f1 100644
@@ -781,12 +781,11 @@ endif
 
 # For a merged /usr, ensure that /lib, /bin and /sbin and their /usr
 # counterparts are appropriately setup as symlinks ones to the others.
-ifeq ($(BR2_ROOTFS_MERGED_USR),y)
 	@$(call MESSAGE,"Sanity check in overlays $(call qstrip,$(BR2_ROOTFS_OVERLAY))")
 	support/scripts/check-merged \
 		--type overlay \
+		$(if $(BR2_ROOTFS_MERGED_USR),--merged-usr) \
 		$(call qstrip,$(BR2_ROOTFS_OVERLAY))
-endif # merged /usr
 
 	$(foreach d, $(call qstrip,$(BR2_ROOTFS_OVERLAY)), \
 		@$(call MESSAGE,"Copying overlay $(d)")$(sep) \

index 82e1506156..5d65b95ecf 100644
@@ -23,19 +23,12 @@ $(error No path specified for the custom skeleton)
 endif
 endif
 
-# For a merged /usr, ensure that /lib, /bin and /sbin and their /usr
-# counterparts are appropriately setup as symlinks ones to the others.
-ifeq ($(BR2_ROOTFS_MERGED_USR),y)
-define SKELETON_CUSTOM_NOT_MERGED_USR_DIRS
+define SKELETON_CUSTOM_CONFIGURE_CMDS
 	support/scripts/check-merged \
 		--type skeleton \
+		$(if $(BR2_ROOTFS_MERGED_USR),--merged-usr) \
 		$(SKELETON_CUSTOM_PATH)
 endef
-endif # merged /usr
-
-define SKELETON_CUSTOM_CONFIGURE_CMDS
-	$(SKELETON_CUSTOM_NOT_MERGED_USR_DIRS)
-endef
 
 # The target-dir-warning file and the lib{32,64} symlinks are the only
 # things we customise in the custom skeleton.

index 34e726b4fb..3cccd68dd7 100755
@@ -13,6 +13,7 @@
 #
 # Input:
 #   --type TYPE     the type of root to check: 'skeleton' or 'overlay'
+#   --merged-usr    check for merged /usr
 #   $*:             the root directories (skeleton, overlays) to check
 # Output:
 #   stdout:         the list of non-compliant paths (empty if compliant).

@@ -21,17 +22,22 @@
 #   !0:             if any directory to check is improperly merged
 #
 
-opts="type:"
+opts="type:,merged-usr"
 ARGS="$(getopt -n check-merged -o "" -l "${opts}" -- "${@}")" || exit 1
 eval set -- "${ARGS}"
 
 type=
+merged_usr=false
 while :; do
 	case "${1}" in
 	(--type)
 		type="${2}"
 		shift 2
 		;;
+	(--merged-usr)
+		merged_usr=true
+		shift
+		;;
 	(--)
 		shift
 		break

@@ -101,12 +107,14 @@ test_dir() {
 is_success=true
 for root; do
 	first=true
-	test_dir "${type}" "${root}" "/" "usr/bin"
-	test_dir "${type}" "${root}" "/" "usr/lib"
-	test_dir "${type}" "${root}" "/" "usr/sbin"
-	test_merged "${type}" "${root}" "/" "bin" "usr/bin"
-	test_merged "${type}" "${root}" "/" "lib" "usr/lib"
-	test_merged "${type}" "${root}" "/" "sbin" "usr/sbin"
+	if ${merged_usr}; then
+		test_dir "${type}" "${root}" "/" "usr/bin"
+		test_dir "${type}" "${root}" "/" "usr/lib"
+		test_dir "${type}" "${root}" "/" "usr/sbin"
+		test_merged "${type}" "${root}" "/" "bin" "usr/bin"
+		test_merged "${type}" "${root}" "/" "lib" "usr/lib"
+		test_merged "${type}" "${root}" "/" "sbin" "usr/sbin"
+	fi
 done
 
 ${is_success}

index 2ff944f6f1..5fd49c3e9b 100644
@@ -785,6 +785,7 @@ endif
 	support/scripts/check-merged \
 		--type overlay \
 		$(if $(BR2_ROOTFS_MERGED_USR),--merged-usr) \
+		$(if $(BR2_ROOTFS_MERGED_BIN),--merged-bin) \
 		$(call qstrip,$(BR2_ROOTFS_OVERLAY))
 
 	$(foreach d, $(call qstrip,$(BR2_ROOTFS_OVERLAY)), \

index 5d65b95ecf..7c79500046 100644
@@ -27,6 +27,7 @@ define SKELETON_CUSTOM_CONFIGURE_CMDS
 	support/scripts/check-merged \
 		--type skeleton \
 		$(if $(BR2_ROOTFS_MERGED_USR),--merged-usr) \
+		$(if $(BR2_ROOTFS_MERGED_BIN),--merged-bin) \
 		$(SKELETON_CUSTOM_PATH)
 endef
 

index 3cccd68dd7..fbda49f1c0 100755
@@ -1,7 +1,9 @@
 #!/usr/bin/env bash
 #
-# Check if a given custom skeleton or overlay complies to the merged /usr
+# Check if a given custom skeleton or overlay complies to the merged
 # requirements:
+#
+# - for merged-usr:
 #   /bin            missing, or a relative symlink to usr/bin
 #   /lib            missing, or a relative symlink to usr/lib
 #   /sbin           missing, or a relative symlink to usr/sbin

@@ -11,9 +13,14 @@
 #
 # *: must be present for skeletons, can be missing for overlays
 #
+# - for merged-bin: all of the above, except:
+#   /usr/sbin       missing, or a relative symlink to bin (thus points
+#                   to /usr/bin)
+#
 # Input:
 #   --type TYPE     the type of root to check: 'skeleton' or 'overlay'
 #   --merged-usr    check for merged /usr
+#   --merged-bin    check for merged /usr/bin
 #   $*:             the root directories (skeleton, overlays) to check
 # Output:
 #   stdout:         the list of non-compliant paths (empty if compliant).

@@ -22,12 +29,13 @@
 #   !0:             if any directory to check is improperly merged
 #
 
-opts="type:,merged-usr"
+opts="type:,merged-usr,merged-bin"
 ARGS="$(getopt -n check-merged -o "" -l "${opts}" -- "${@}")" || exit 1
 eval set -- "${ARGS}"
 
 type=
 merged_usr=false
+merged_bin=false
 while :; do
 	case "${1}" in
 	(--type)

@@ -38,6 +46,10 @@ while :; do
 		merged_usr=true
 		shift
 		;;
+	(--merged-bin)
+		merged_bin=true
+		shift
+		;;
 	(--)
 		shift
 		break

@@ -110,10 +122,14 @@ for root; do
 	if ${merged_usr}; then
 		test_dir "${type}" "${root}" "/" "usr/bin"
 		test_dir "${type}" "${root}" "/" "usr/lib"
-		test_dir "${type}" "${root}" "/" "usr/sbin"
 		test_merged "${type}" "${root}" "/" "bin" "usr/bin"
 		test_merged "${type}" "${root}" "/" "lib" "usr/lib"
 		test_merged "${type}" "${root}" "/" "sbin" "usr/sbin"
+		if ${merged_bin}; then
+			test_merged "${type}" "${root}" "/usr/" "sbin" "bin"
+		else
+			test_dir "${type}" "${root}" "/" "usr/sbin"
+		fi
 	fi
 done
 

index 32462241a5..0652b94a3b 100644
@@ -343,6 +343,16 @@ config BR2_ROOTFS_MERGED_USR
 	  symlinks to their counterparts in /usr. In this case, /usr can
 	  not be a separate filesystem.
 
+config BR2_ROOTFS_MERGED_BIN
+	bool "Merged /usr/bin"
+	depends on BR2_ROOTFS_MERGED_USR
+	help
+	  If you say 'n' here, then /usr/bin and /usr/sbin will be
+	  separate directories; this is the historical UNIX way.
+
+	  If you say 'y' here, then /usr/sbin will be a relative
+	  symlink to /usr/bin.
+
 if BR2_ROOTFS_SKELETON_DEFAULT
 
 config BR2_TARGET_ENABLE_ROOT_LOGIN

@@ -529,6 +539,7 @@ endif # BR2_ROOTFS_SKELETON_DEFAULT
 
 config BR2_SYSTEM_DEFAULT_PATH
 	string "Set the system's default PATH"
+	default "/usr/bin" if BR2_ROOTFS_MERGED_BIN
 	default "/usr/bin:/usr/sbin" if BR2_ROOTFS_MERGED_USR
 	default "/bin:/sbin:/usr/bin:/usr/sbin"
 	help

deleted file mode 100644
index e69de29bb2..0000000000

index 8fe2c138b0..52e810868a 100644
@@ -32,18 +32,30 @@
 #   set inittab to remount root read-write or read-only
 #
 
-# This function handles the merged or non-merged /usr cases
+# This function handles the merged or non-merged /usr, and merged or
+# non-merged /usr/bin cases
 ifeq ($(BR2_ROOTFS_MERGED_USR),y)
+ifeq ($(BR2_ROOTFS_MERGED_BIN),y)
+define SYSTEM_SBIN_SYMLINKS_OR_DIRS
+	ln -snf bin $(1)/usr/sbin
+endef
+else
+define SYSTEM_SBIN_SYMLINKS_OR_DIRS
+	$(INSTALL) -d -m 0755 $(1)/usr/sbin
+endef
+endif
 define SYSTEM_USR_SYMLINKS_OR_DIRS
 	ln -snf usr/bin $(1)/bin
 	ln -snf usr/sbin $(1)/sbin
 	ln -snf usr/lib $(1)/lib
+	$(SYSTEM_SBIN_SYMLINKS_OR_DIRS)
 endef
 else
 define SYSTEM_USR_SYMLINKS_OR_DIRS
 	$(INSTALL) -d -m 0755 $(1)/bin
 	$(INSTALL) -d -m 0755 $(1)/sbin
 	$(INSTALL) -d -m 0755 $(1)/lib
+	$(INSTALL) -d -m 0755 $(1)/usr/sbin
 endef
 endif
 

index fbda49f1c0..bff6ae2b7b 100755
@@ -3,16 +3,21 @@
 # Check if a given custom skeleton or overlay complies to the merged
 # requirements:
 #
-# - for merged-usr:
-#   /bin            missing, or a relative symlink to usr/bin
-#   /lib            missing, or a relative symlink to usr/lib
-#   /sbin           missing, or a relative symlink to usr/sbin
+# - for unmerged:
+#   /bin            missing*, or an existing directory; not a symlink
+#   /lib            missing*, or an existing directory; not a symlink
+#   /sbin           missing*, or an existing directory; not a symlink
 #   /usr/bin/       missing*, or an existing directory; not a symlink
 #   /usr/lib/       missing*, or an existing directory; not a symlink
 #   /usr/sbin/      missing*, or an existing directory; not a symlink
 #
 # *: must be present for skeletons, can be missing for overlays
 #
+# - for merged-usr: all of the above, except:
+#   /bin            missing, or a relative symlink to usr/bin
+#   /lib            missing, or a relative symlink to usr/lib
+#   /sbin           missing, or a relative symlink to usr/sbin
+#
 # - for merged-bin: all of the above, except:
 #   /usr/sbin       missing, or a relative symlink to bin (thus points
 #                   to /usr/bin)

@@ -119,9 +124,9 @@ test_dir() {
 is_success=true
 for root; do
 	first=true
+	test_dir "${type}" "${root}" "/" "usr/bin"
+	test_dir "${type}" "${root}" "/" "usr/lib"
 	if ${merged_usr}; then
-		test_dir "${type}" "${root}" "/" "usr/bin"
-		test_dir "${type}" "${root}" "/" "usr/lib"
 		test_merged "${type}" "${root}" "/" "bin" "usr/bin"
 		test_merged "${type}" "${root}" "/" "lib" "usr/lib"
 		test_merged "${type}" "${root}" "/" "sbin" "usr/sbin"

@@ -130,6 +135,11 @@ for root; do
 		else
 			test_dir "${type}" "${root}" "/" "usr/sbin"
 		fi
+	else
+		test_dir "${type}" "${root}" "/" "bin"
+		test_dir "${type}" "${root}" "/" "lib"
+		test_dir "${type}" "${root}" "/" "sbin"
+		test_dir "${type}" "${root}" "/" "usr/sbin"
 	fi
 done
 

index a6d193b49e..60772c9e7b 100644
@@ -125,6 +125,7 @@ define COREUTILS_CREATE_TEST_SYMLINK
 endef
 COREUTILS_POST_INSTALL_TARGET_HOOKS += COREUTILS_CREATE_TEST_SYMLINK
 
+ifeq ($(BR2_ROOTFS_MERGED_BIN),)
 # gnu thinks chroot is in bin, debian thinks it's in sbin
 ifeq ($(BR2_PACKAGE_COREUTILS_INDIVIDUAL_BINARIES),y)
 define COREUTILS_FIX_CHROOT_LOCATION

@@ -137,6 +138,7 @@ define COREUTILS_FIX_CHROOT_LOCATION
 endef
 endif
 COREUTILS_POST_INSTALL_TARGET_HOOKS += COREUTILS_FIX_CHROOT_LOCATION
+endif
 
 # Explicitly install ln and realpath, which we *are* insterested in.
 # A lot of other programs still get installed, however, but disabling

index dfdd17b955..cbf89bca9d 100644
@@ -68,16 +68,24 @@ ifeq ($(BR2_PACKAGE_KMOD_TOOLS),y)
 KMOD_LICENSE += , GPL-2.0+ (tools)
 KMOD_LICENSE_FILES += COPYING
 
-# /sbin is really /usr/sbin with merged /usr, so adjust relative symlink
+# /sbin is really /usr/sbin with merged /usr, and /usr/sbin is
+# really /usr/bin with merged-bin, so adjust relative symlink
 ifeq ($(BR2_ROOTFS_MERGED_USR),y)
+ifeq ($(BR2_ROOTFS_MERGED_BIN),y)
+KMOD_BIN_PATH = kmod
+KMOD_SBIN_DIR = bin
+else
 KMOD_BIN_PATH = ../bin/kmod
+KMOD_SBIN_DIR = sbin
+endif
 else
 KMOD_BIN_PATH = ../usr/bin/kmod
+KMOD_SBIN_DIR = sbin
 endif
 
 define KMOD_INSTALL_TOOLS
 	for i in depmod insmod lsmod modinfo modprobe rmmod; do \
-		ln -sf $(KMOD_BIN_PATH) $(TARGET_DIR)/sbin/$$i; \
+		ln -sf $(KMOD_BIN_PATH) $(TARGET_DIR)/$(KMOD_SBIN_DIR)/$$i; \
 	done
 endef
 

index 3098a81a72..d1abdbdc9e 100644
@@ -75,7 +75,13 @@ endif
 # ${usrlib_execdir} (/usr/lib) to ${libdir} (/lib), since both paths are
 # the same when merged usr is in use.
 ifeq ($(BR2_ROOTFS_MERGED_USR),y)
-UTIL_LINUX_CONF_OPTS += --bindir=/usr/bin --sbindir=/usr/sbin --libdir=/usr/lib
+UTIL_LINUX_CONF_OPTS += --bindir=/usr/bin --libdir=/usr/lib
+# Ditto for /usr/sbin and /usr/bin when merge sbin is in use
+ifeq ($(BR2_ROOTFS_MERGED_BIN),y)
+UTIL_LINUX_CONF_OPTS += --sbindir=/usr/bin
+else
+UTIL_LINUX_CONF_OPTS += --sbindir=/usr/sbin
+endif
 endif
 
 ifeq ($(BR2_PACKAGE_SYSTEMD),y)

index 0468a00bf0..344abee8b3 100644
@@ -42,10 +42,16 @@ endef
 
 # ifconfig & route reside in /sbin for busybox, so ensure we don't end
 # up with two versions of those.
-define NET_TOOLS_INSTALL_TARGET_CMDS
-	$(TARGET_MAKE_ENV) $(MAKE) -C $(@D) DESTDIR=$(TARGET_DIR) install
+ifeq ($(BR2_ROOTFS_MERGED_BIN),)
+define NET_TOOLS_INSTALL_MV_BINS
 	mv -f $(TARGET_DIR)/bin/ifconfig $(TARGET_DIR)/sbin/ifconfig
 	mv -f $(TARGET_DIR)/bin/route $(TARGET_DIR)/sbin/route
 endef
+endif
+
+define NET_TOOLS_INSTALL_TARGET_CMDS
+	$(TARGET_MAKE_ENV) $(MAKE) -C $(@D) DESTDIR=$(TARGET_DIR) install
+	$(NET_TOOLS_INSTALL_MV_BINS)
+endef
 
 $(eval $(generic-package))

index f3fdaaec07..21c710d0fb 100644
@@ -96,6 +96,10 @@ copy_toolchain_lib_root = \
 # Note that the 'locale' directories are not copied. They are huge
 # (400+MB) in CodeSourcery toolchains, and they are not really useful.
 #
+# usr/sbin may be a directory in the source toolchain, but a symlink
+# in the destination sysroot, when we are using a merged-bin. Account
+# for that.
+#
 # $1: main sysroot directory of the toolchain
 # $2: arch specific sysroot directory of the toolchain
 # $3: arch specific subdirectory in the sysroot

@@ -109,13 +113,13 @@ copy_toolchain_sysroot = \
 	ARCH_SUBDIR="$(strip $3)"; \
 	ARCH_LIB_DIR="$(strip $4)" ; \
 	SUPPORT_LIB_DIR="$(strip $5)" ; \
-	for i in etc $${ARCH_LIB_DIR} sbin usr usr/$${ARCH_LIB_DIR}; do \
+	for i in etc $${ARCH_LIB_DIR} sbin usr usr/$${ARCH_LIB_DIR} usr/sbin; do \
 		if [ ! -d $${ARCH_SYSROOT_DIR}/$$i ] ; then \
 			continue ; \
 		fi ; \
 		if [ "$$i" = "usr" ]; then \
 			rsync -au --chmod=u=rwX,go=rX --exclude 'locale/' \
-				--include '/libexec*/' --exclude '/lib*/' \
+				--include '/libexec*/' --exclude '/lib*/' --exclude '/sbin' \
 				$${ARCH_SYSROOT_DIR}/$$i/ $(STAGING_DIR)/$$i/ ; \
 		else \
 			rsync -au --chmod=u=rwX,go=rX --exclude 'locale/' \

index 0cb10ea3d8..931134911a 100644
@@ -25,6 +25,7 @@ menuconfig BR2_PACKAGE_SYSTEMD
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_8
 	depends on BR2_HOST_GCC_AT_LEAST_8 # host-systemd
 	select BR2_ROOTFS_MERGED_USR
+	select BR2_ROOTFS_MERGED_BIN
 	select BR2_PACKAGE_HAS_UDEV
 	select BR2_PACKAGE_DBUS if !BR2_PACKAGE_DBUS_BROKER # runtime
 	select BR2_PACKAGE_LIBCAP

index 05a65223b3..7fdd5d1798 100644
@@ -31,6 +31,25 @@ class InitSystemSystemdBase(InitSystemBase):
             self.start_emulator(fs)
         self.check_init("/lib/systemd/systemd")
 
+        # Test there is no tainted flag.
+        output, ret = self.emulator.run("systemctl --no-pager status")
+        self.assertEqual(ret, 0, f"'systemctl status' failed with exit code {ret}, with:\n{output}")
+        try:
+            # 'support-ended' tainted flag is only set based on the
+            # SUPPORT_END variable in /etc/os-release; as we don't set
+            # it in Buildroot, we can't get that flag in the runtime
+            # tests, even on our maintenance branches, so we don't need
+            # to filter it out.
+            tainted_flags = [
+                "".join(line.split(":")[1:]).strip()
+                for line in output
+                if line.strip().startswith("Tainted: ")
+            ][0]
+            raise RuntimeError(f"Tainted flags: {tainted_flags}")
+        except IndexError:
+            # No tainted flag \o/
+            pass
+
         # Test all units are OK
         output, _ = self.emulator.run("systemctl --no-pager --failed --no-legend")
         self.assertEqual(len(output), 0)