diff --git a/.gitignore b/.gitignore
index 85027773b..5ec57a167 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,6 +19,3 @@ GPATH
 examples/*/sdkconfig
 examples/*/sdkconfig.old
 examples/*/build
-
-# Bootloader files
-components/bootloader/src/sdkconfig.old
\ No newline at end of file
diff --git a/components/bootloader/Makefile.projbuild b/components/bootloader/Makefile.projbuild
index d45cf144e..91be3a6d6 100644
--- a/components/bootloader/Makefile.projbuild
+++ b/components/bootloader/Makefile.projbuild
@@ -11,20 +11,23 @@
 ifeq ("$(IS_BOOTLOADER_BUILD)","")
 
 BOOTLOADER_COMPONENT_PATH := $(COMPONENT_PATH)
-BOOTLOADER_BUILD_DIR=$(BUILD_DIR_BASE)/bootloader
+BOOTLOADER_BUILD_DIR=$(abspath $(BUILD_DIR_BASE)/bootloader)
 BOOTLOADER_BIN=$(BOOTLOADER_BUILD_DIR)/bootloader.bin
+BOOTLOADER_SDKCONFIG=$(BOOTLOADER_BUILD_DIR)/sdkconfig
+
+# Custom recursive make for bootloader sub-project
+BOOTLOADER_MAKE=+$(MAKE) -C $(BOOTLOADER_COMPONENT_PATH)/src \
+	V=$(V) SDKCONFIG=$(BOOTLOADER_SDKCONFIG) \
+	BUILD_DIR_BASE=$(BOOTLOADER_BUILD_DIR) \
 
 .PHONY: bootloader-clean bootloader-flash bootloader $(BOOTLOADER_BIN)
 
-$(BOOTLOADER_BIN): $(COMPONENT_PATH)/src/sdkconfig
-	$(Q) PROJECT_PATH= \
-	BUILD_DIR_BASE=$(BOOTLOADER_BUILD_DIR) \
-	$(MAKE) -C $(BOOTLOADER_COMPONENT_PATH)/src MAKEFLAGS= V=$(V) TARGET_BIN_LAYOUT="$(BOOTLOADER_TARGET_BIN_LAYOUT)" $(BOOTLOADER_BIN)
+$(BOOTLOADER_BIN): | $(BOOTLOADER_BUILD_DIR)/sdkconfig
+	$(Q) $(BOOTLOADER_MAKE) $@
 
 bootloader-clean:
-	$(Q) PROJECT_PATH= \
-	BUILD_DIR_BASE=$(BOOTLOADER_BUILD_DIR) \
-	$(MAKE) -C $(BOOTLOADER_COMPONENT_PATH)/src app-clean MAKEFLAGS= V=$(V)
+	$(Q) $(BOOTLOADER_MAKE) app-clean config-clean
+	$(Q) rm -f $(BOOTLOADER_SDKCONFIG) $(BOOTLOADER_SDKCONFIG).old
 
 clean: bootloader-clean
 
@@ -36,14 +39,17 @@ all_binaries: $(BOOTLOADER_BIN)
 
 ESPTOOL_ALL_FLASH_ARGS += 0x1000 $(BOOTLOADER_BIN)
 
-# synchronise the project level config to the component's
-# config
-$(COMPONENT_PATH)/src/sdkconfig: $(PROJECT_PATH)/sdkconfig
-	$(Q) cp $< $@
-
 # bootloader-flash calls flash in the bootloader dummy project
 bootloader-flash: $(BOOTLOADER_BIN)
-	$(MAKE) -C $(BOOTLOADER_COMPONENT_PATH)/src flash MAKEFLAGS= V=$(V)
+	$(BOOTLOADER_MAKE) flash
+
+# synchronise the project level config to the bootloader's
+# config
+$(BOOTLOADER_SDKCONFIG): $(PROJECT_PATH)/sdkconfig | $(BOOTLOADER_BUILD_DIR)
+	$(Q) cp $< $@
+
+$(BOOTLOADER_BUILD_DIR):
+	$(Q) mkdir -p $@
 
 else
 CFLAGS += -D BOOTLOADER_BUILD=1 -I $(IDF_PATH)/components/esp32/include 
diff --git a/components/esp32/component.mk b/components/esp32/component.mk
index b41acee60..788f88012 100644
--- a/components/esp32/component.mk
+++ b/components/esp32/component.mk
@@ -6,7 +6,7 @@
 # lib(subdirectory_name).a in the build directory. This behaviour is entirely configurable,
 # please read the esp-idf build system document if you need to do this.
 #
--include $(PROJECT_PATH)/build/include/config/auto.conf
+-include include/config/auto.conf
 
 COMPONENT_SRCDIRS := . hwcrypto
 
@@ -44,6 +44,8 @@ $(COMPONENT_LIBRARY): $(ALL_LIB_FILES)
 # saves us from having to add the target to a Makefile.projbuild
 $(COMPONENT_LIBRARY): esp32_out.ld
 
+# .. is BUILD_DIR_BASE here, as component makefiles
+# are evaluated with CWD=component build dir
 esp32_out.ld: $(COMPONENT_PATH)/ld/esp32.ld ../include/sdkconfig.h
 	$(CC) -I ../include -C -P -x c -E $< -o $@
 
diff --git a/make/common.mk b/make/common.mk
index 14aa4074b..2b7376a4d 100644
--- a/make/common.mk
+++ b/make/common.mk
@@ -6,7 +6,7 @@
 #
 # (Note that we only rebuild auto.conf automatically for some targets,
 # see project_config.mk for details.)
--include $(PROJECT_PATH)/build/include/config/auto.conf
+-include $(BUILD_DIR_BASE)/include/config/auto.conf
 
 #Handling of V=1/VERBOSE=1 flag
 #
diff --git a/make/project.mk b/make/project.mk
index d91165cfd..2b2eff3f5 100644
--- a/make/project.mk
+++ b/make/project.mk
@@ -37,6 +37,7 @@ help:
 	@echo "'make partition_table', etc, etc."
 
 # disable built-in make rules, makes debugging saner
+MAKEFLAGS_OLD := $(MAKEFLAGS)
 MAKEFLAGS +=-rR
 
 # Figure out PROJECT_PATH if not set
@@ -50,6 +51,7 @@ endif
 #The directory where we put all objects/libraries/binaries. The project Makefile can
 #configure this if needed.
 BUILD_DIR_BASE ?= $(PROJECT_PATH)/build
+export BUILD_DIR_BASE
 
 #Component directories. These directories are searched for components.
 #The project Makefile can override these component dirs, or define extra component directories.
@@ -105,7 +107,7 @@ COMPONENT_INCLUDES := $(abspath $(foreach comp,$(COMPONENT_PATHS_BUILDABLE),$(ad
 	$(call GetVariable,$(comp),COMPONENT_ADD_INCLUDEDIRS))))
 
 #Also add project include path, for sdk includes
-COMPONENT_INCLUDES += $(PROJECT_PATH)/build/include/
+COMPONENT_INCLUDES += $(abspath $(BUILD_DIR_BASE)/include/)
 export COMPONENT_INCLUDES
 
 #COMPONENT_LDFLAGS has a list of all flags that are needed to link the components together. It's collected
@@ -230,7 +232,7 @@ define GenerateComponentPhonyTarget
 # $(2) - target to generate (build, clean)
 .PHONY: $(notdir $(1))-$(2)
 $(notdir $(1))-$(2): | $(BUILD_DIR_BASE)/$(notdir $(1))
-	@+$(MAKE) -C $(BUILD_DIR_BASE)/$(notdir $(1)) -f $(1)/component.mk COMPONENT_BUILD_DIR=$(BUILD_DIR_BASE)/$(notdir $(1)) $(2)
+	$(Q) +$(MAKE) -C $(BUILD_DIR_BASE)/$(notdir $(1)) -f $(1)/component.mk COMPONENT_BUILD_DIR=$(BUILD_DIR_BASE)/$(notdir $(1)) $(2)
 endef
 
 define GenerateComponentTargets
diff --git a/make/project_config.mk b/make/project_config.mk
index d2909bb30..7ca83ce5a 100644
--- a/make/project_config.mk
+++ b/make/project_config.mk
@@ -7,38 +7,38 @@ COMPONENT_KCONFIGS_PROJBUILD := $(foreach component,$(COMPONENT_PATHS),$(wildcar
 #For doing make menuconfig etc
 KCONFIG_TOOL_DIR=$(IDF_PATH)/tools/kconfig
 
-# clear MAKEFLAGS as the menuconfig makefile uses implicit compile rules
+# set SDKCONFIG to the project's sdkconfig,
+# unless it's overriden (happens for bootloader)
+SDKCONFIG ?= $(PROJECT_PATH)/sdkconfig
+
+# reset MAKEFLAGS as the menuconfig makefile uses implicit compile rules
 $(KCONFIG_TOOL_DIR)/mconf $(KCONFIG_TOOL_DIR)/conf:
-	MAKEFLAGS="" \
-	CC=$(HOSTCC) LD=$(HOSTLD) \
+	MAKEFLAGS=$(ORIGINAL_MAKEFLAGS) CC=$(HOSTCC) LD=$(HOSTLD) \
 	$(MAKE) -C $(KCONFIG_TOOL_DIR)
 
+# use a wrapper environment for where we run Kconfig tools
+KCONFIG_TOOL_ENV=KCONFIG_AUTOHEADER=$(abspath $(BUILD_DIR_BASE)/include/sdkconfig.h) \
+	COMPONENT_KCONFIGS="$(COMPONENT_KCONFIGS)" KCONFIG_CONFIG=$(SDKCONFIG) \
+	COMPONENT_KCONFIGS_PROJBUILD="$(COMPONENT_KCONFIGS_PROJBUILD)"
+
 menuconfig: $(KCONFIG_TOOL_DIR)/mconf $(IDF_PATH)/Kconfig $(BUILD_DIR_BASE)
 	$(summary) MENUCONFIG
-	$(Q) KCONFIG_AUTOHEADER=$(PROJECT_PATH)/build/include/sdkconfig.h \
-	KCONFIG_CONFIG=$(PROJECT_PATH)/sdkconfig \
-	COMPONENT_KCONFIGS="$(COMPONENT_KCONFIGS)" \
-	COMPONENT_KCONFIGS_PROJBUILD="$(COMPONENT_KCONFIGS_PROJBUILD)" \
-	$(KCONFIG_TOOL_DIR)/mconf $(IDF_PATH)/Kconfig
+	$(Q) $(KCONFIG_TOOL_ENV) $(KCONFIG_TOOL_DIR)/mconf $(IDF_PATH)/Kconfig
 
-ifeq ("$(wildcard $(PROJECT_PATH)/sdkconfig)","")
+ifeq ("$(wildcard $(SDKCONFIG))","")
 #No sdkconfig found. Need to run menuconfig to make this if we need it.
-$(PROJECT_PATH)/sdkconfig: menuconfig
+$(SDKCONFIG): menuconfig
 endif
 
 defconfig: $(KCONFIG_TOOL_DIR)/mconf $(IDF_PATH)/Kconfig $(BUILD_DIR_BASE)
 	$(summary) DEFCONFIG
-	$(Q) mkdir -p $(PROJECT_PATH)/build/include/config
-	$(Q) KCONFIG_AUTOHEADER=$(PROJECT_PATH)/build/include/sdkconfig.h \
-	KCONFIG_CONFIG=$(PROJECT_PATH)/sdkconfig \
-	COMPONENT_KCONFIGS="$(COMPONENT_KCONFIGS)" \
-	COMPONENT_KCONFIGS_PROJBUILD="$(COMPONENT_KCONFIGS_PROJBUILD)" \
-	$(KCONFIG_TOOL_DIR)/conf --olddefconfig $(IDF_PATH)/Kconfig
+	$(Q) mkdir -p $(BUILD_DIR_BASE)/include/config
+	$(Q) $(KCONFIG_TOOL_ENV) $(KCONFIG_TOOL_DIR)/conf --olddefconfig $(IDF_PATH)/Kconfig
 
 # Work out of whether we have to build the Kconfig makefile
 # (auto.conf), or if we're in a situation where we don't need it
 NON_CONFIG_TARGETS := clean %-clean get_variable help menuconfig defconfig
-AUTO_CONF_REGEN_TARGET := $(PROJECT_PATH)/build/include/config/auto.conf
+AUTO_CONF_REGEN_TARGET := $(BUILD_DIR_BASE)/include/config/auto.conf
 
 # disable AUTO_CONF_REGEN_TARGET if all targets are non-config targets
 # (and not building default target)
@@ -46,19 +46,15 @@ ifneq ("$(MAKECMDGOALS)","")
 ifeq ($(filter $(NON_CONFIG_TARGETS), $(MAKECMDGOALS)),$(MAKECMDGOALS))
 AUTO_CONF_REGEN_TARGET :=
 # dummy target
-$(PROJECT_PATH)/build/include/config/auto.conf:
+$(BUILD_DIR_BASE)/include/config/auto.conf:
 endif
 endif
 
-$(AUTO_CONF_REGEN_TARGET) $(PROJECT_PATH)/build/include/sdkconfig.h: $(PROJECT_PATH)/sdkconfig $(KCONFIG_TOOL_DIR)/conf $(COMPONENT_KCONFIGS) $(COMPONENT_KCONFIGS_PROJBUILD)
+$(AUTO_CONF_REGEN_TARGET) $(BUILD_DIR_BASE)/include/sdkconfig.h: $(SDKCONFIG) $(KCONFIG_TOOL_DIR)/conf $(COMPONENT_KCONFIGS) $(COMPONENT_KCONFIGS_PROJBUILD)
 	$(summary) GENCONFIG
-	$(Q) mkdir -p $(PROJECT_PATH)/build/include/config
-	$(Q) cd build; KCONFIG_AUTOHEADER="$(PROJECT_PATH)/build/include/sdkconfig.h" \
-	KCONFIG_CONFIG=$(PROJECT_PATH)/sdkconfig \
-	COMPONENT_KCONFIGS="$(COMPONENT_KCONFIGS)" \
-	COMPONENT_KCONFIGS_PROJBUILD="$(COMPONENT_KCONFIGS_PROJBUILD)" \
-	$(KCONFIG_TOOL_DIR)/conf --silentoldconfig $(IDF_PATH)/Kconfig
-	$(Q) touch $(AUTO_CONF_REGEN_TARGET) $(PROJECT_PATH)/build/include/sdkconfig.h
+	$(Q) mkdir -p $(BUILD_DIR_BASE)/include/config
+	$(Q) cd $(BUILD_DIR_BASE); $(KCONFIG_TOOL_ENV) $(KCONFIG_TOOL_DIR)/conf --silentoldconfig $(IDF_PATH)/Kconfig
+	$(Q) touch $(AUTO_CONF_REGEN_TARGET) $(BUILD_DIR_BASE)/include/sdkconfig.h
 # touch to ensure both output files are newer - as 'conf' can also update sdkconfig (a dependency). Without this,
 # sometimes you can get an infinite make loop on Windows where sdkconfig always gets regenerated newer
 # than the target(!)
@@ -68,4 +64,4 @@ clean: config-clean
 config-clean:
 	$(summary RM CONFIG)
 	$(MAKE) -C $(KCONFIG_TOOL_DIR) clean
-	$(Q) rm -rf $(PROJECT_PATH)/build/include/config $(PROJECT_PATH)/build/include/sdkconfig.h
+	$(Q) rm -rf $(BUILD_DIR_BASE)/include/config $(BUILD_DIR_BASE)/include/sdkconfig.h
diff --git a/make/test_build_system.sh b/make/test_build_system.sh
index 86be1f82e..7c8cbc1f1 100755
--- a/make/test_build_system.sh
+++ b/make/test_build_system.sh
@@ -2,7 +2,7 @@
 #
 # Test the build system for basic consistency
 #
-# Just a bash script that tests some likely make failure scenarios in a row
+# A bash script that tests some likely make failure scenarios in a row
 # Creates its own test build directory under TMP and cleans it up when done.
 #
 # Environment variables:
@@ -11,6 +11,18 @@
 # ESP_IDF_TEMPLATE_GIT - Can override git clone source for template app. Otherwise github.
 # NOCLEANUP - Set to '1' if you want the script to leave its temporary directory when done, for post-mortem.
 #
+#
+# Internals:
+# * The tests run in sequence & the system keeps track of all failures to print at the end.
+# * BUILD directory is set to default BUILD_DIR_BASE
+# * The "print_status" function both prints a status line to the log and keeps track of which test is running.
+# * Calling the "failure" function prints a failure message to the log and also adds to the list of failures to print at the end.
+# * The function "assert_built" tests for a file relative to the BUILD directory.
+# * The function "take_build_snapshot" can be paired with the functions "assert_rebuilt" and "assert_not_rebuilt" to compare file timestamps and verify if they were rebuilt or not since the snapshot was taken.
+#
+# To add a new test case, add it to the end of the run_tests function. Note that not all test cases do comprehensive cleanup
+# (although very invasive ones like appending CRLFs to all files take a copy of the esp-idf tree), however the clean_build_dir
+# function can be used to force-delete all files from the build output directory.
 
 # Set up some variables
 #
@@ -21,110 +33,137 @@ export V=1
 
 function run_tests()
 {
-	FAILURES=
-	STATUS="Starting"
-	print_status "Checking prerequisites"
-	[ -z ${IDF_PATH} ] && echo "IDF_PATH is not set. Need path to esp-idf installation." && exit 2
+    FAILURES=
+    STATUS="Starting"
+    print_status "Checking prerequisites"
+    [ -z ${IDF_PATH} ] && echo "IDF_PATH is not set. Need path to esp-idf installation." && exit 2
 
-	print_status "Cloning template from ${ESP_IDF_TEMPLATE_GIT}..."
-	git clone ${ESP_IDF_TEMPLATE_GIT} template
-	cd template
-	git checkout ${CI_BUILD_REF_NAME} || echo "Using esp-idf-template default branch..."
+    print_status "Cloning template from ${ESP_IDF_TEMPLATE_GIT}..."
+    git clone ${ESP_IDF_TEMPLATE_GIT} template
+    cd template
+    git checkout ${CI_BUILD_REF_NAME} || echo "Using esp-idf-template default branch..."
 
-	print_status "Updating template config..."
-	make defconfig || exit $?
+    print_status "Updating template config..."
+    make defconfig || exit $?
 
-	BOOTLOADER_BINS="bootloader/bootloader.elf bootloader/bootloader.bin"
-	APP_BINS="app-template.elf app-template.bin"
+    BOOTLOADER_BINS="bootloader/bootloader.elf bootloader/bootloader.bin"
+    APP_BINS="app-template.elf app-template.bin"
 
-	print_status "Initial clean build"
-	# if make fails here, everything fails
-	make || exit $?
-	# check all the expected build artifacts from the clean build
-	assert_built ${APP_BINS} ${BOOTLOADER_BINS} partitions_singleapp.bin
-	[ -f ${BUILD}/partition*.bin ] || failure "A partition table should have been built"
+    print_status "Initial clean build"
+    # if make fails here, everything fails
+    make || exit $?
+    # check all the expected build artifacts from the clean build
+    assert_built ${APP_BINS} ${BOOTLOADER_BINS} partitions_singleapp.bin
+    [ -f ${BUILD}/partition*.bin ] || failure "A partition table should have been built"
 
-	print_status "Updating component source file rebuilds component"
-	# touch a file & do a build
-	take_build_snapshot
-	touch ${IDF_PATH}/components/esp32/syscalls.c
-	make || failure "Failed to partial build"
-	assert_rebuilt ${APP_BINS} esp32/libesp32.a esp32/syscalls.o
-	assert_not_rebuilt lwip/liblwip.a freertos/libfreertos.a ${BOOTLOADER_BINS} partitions_singleapp.bin
+    print_status "Updating component source file rebuilds component"
+    # touch a file & do a build
+    take_build_snapshot
+    touch ${IDF_PATH}/components/esp32/syscalls.c
+    make || failure "Failed to partial build"
+    assert_rebuilt ${APP_BINS} esp32/libesp32.a esp32/syscalls.o
+    assert_not_rebuilt lwip/liblwip.a freertos/libfreertos.a ${BOOTLOADER_BINS} partitions_singleapp.bin
 
-	print_status "Bootloader source file rebuilds bootloader"
-	take_build_snapshot
-	touch ${IDF_PATH}/components/bootloader/src/main/bootloader_start.c
-	make bootloader || failure "Failed to partial build bootloader"
-	assert_rebuilt ${BOOTLOADER_BINS} bootloader/main/bootloader_start.o
-	assert_not_rebuilt ${APP_BINS} partitions_singleapp.bin
+    print_status "Bootloader source file rebuilds bootloader"
+    take_build_snapshot
+    touch ${IDF_PATH}/components/bootloader/src/main/bootloader_start.c
+    make bootloader || failure "Failed to partial build bootloader"
+    assert_rebuilt ${BOOTLOADER_BINS} bootloader/main/bootloader_start.o
+    assert_not_rebuilt ${APP_BINS} partitions_singleapp.bin
 
-	print_status "Partition CSV file rebuilds partitions"
-	take_build_snapshot
-	touch ${IDF_PATH}/components/partition_table/partitions_singleapp.csv
-	make partition_table
-	assert_rebuilt partitions_singleapp.bin
-	assert_not_rebuilt app-template.bin app-template.elf ${BOOTLOADER_BINS}
+    print_status "Partition CSV file rebuilds partitions"
+    take_build_snapshot
+    touch ${IDF_PATH}/components/partition_table/partitions_singleapp.csv
+    make partition_table || failure "Failed to build partition table"
+    assert_rebuilt partitions_singleapp.bin
+    assert_not_rebuilt app-template.bin app-template.elf ${BOOTLOADER_BINS}
 
-	print_status "Partial build doesn't compile anything by default"
-	take_build_snapshot
-	# verify no build files are refreshed by a partial make
-	ALL_BUILD_FILES=$(find ${BUILD} -type f | sed "s@${BUILD}/@@")
-	make
-	assert_not_rebuilt ${ALL_BUILD_FILES}
+    print_status "Partial build doesn't compile anything by default"
+    take_build_snapshot
+    # verify no build files are refreshed by a partial make
+    ALL_BUILD_FILES=$(find ${BUILD} -type f | sed "s@${BUILD}/@@")
+    make || failure "Partial build failed"
+    assert_not_rebuilt ${ALL_BUILD_FILES}
 
-	print_status "Cleaning should remove all files from build"
-	make clean
-	ALL_BUILD_FILES=$(find ${BUILD} -type f)
-	if [ -n "${ALL_BUILD_FILES}" ]; then
-		 failure "Files weren't cleaned: ${ALL_BUILD_FILES}"
-	fi
+    print_status "Cleaning should remove all files from build"
+    make clean || failure "Failed to make clean"
+    ALL_BUILD_FILES=$(find ${BUILD} -type f)
+    if [ -n "${ALL_BUILD_FILES}" ]; then
+         failure "Files weren't cleaned: ${ALL_BUILD_FILES}"
+    fi
 
     print_status "Bootloader build shouldn't leave build output anywhere else"
-    rm -rf --preserve-root ${BUILD}
+    clean_build_dir
     make bootloader
     # find wizardry: find any file not named sdkconfig.h that
     # isn't in the "bootloader" or "config" directories
     find ${BUILD} -type d \( -name bootloader -o -name config \) -prune , -type f ! -name sdkconfig.h || failure "Bootloader built files outside the bootloader or config directories"
 
-	print_status "Can still clean build if all text files are CRLFs"
-	make clean
-	find . -exec unix2dos {} \; # CRLFify template dir
-	# make a copy of esp-idf and CRLFify it
-	CRLF_ESPIDF=${TESTDIR}/esp-idf-crlf
-	mkdir -p ${CRLF_ESPIDF}
-	cp -rv ${IDF_PATH}/* ${CRLF_ESPIDF}
-	# don't CRLFify executable files, as Linux will fail to execute them
-	find ${CRLF_ESPIDF} -type f ! -perm 755 -exec unix2dos {} \;
-	make IDF_PATH=${CRLF_ESPIDF}
-	# do the same checks we do for the clean build
-	assert_built ${APP_BINS} ${BOOTLOADER_BINS} partitions_singleapp.bin
-	[ -f ${BUILD}/partition*.bin ] || failure "A partition table should have been built in CRLF mode"
+    print_status "Moving BUILD_DIR_BASE out of tree"
+    clean_build_dir
+    OUTOFTREE_BUILD=${TESTDIR}/alt_build
+    make BUILD_DIR_BASE=${OUTOFTREE_BUILD} || failure "Failed to build with BUILD_DIR_BASE overriden"
+    NEW_BUILD_FILES=$(find ${OUTOFREE_BUILD} -type f)
+    if [ -z "${NEW_BUILD_FILES}" ]; then
+        failure "No files found in new build directory!"
+    fi
+    DEFAULT_BUILD_FILES=$(find ${BUILD} -mindepth 1)
+    if [ -n "${DEFAULT_BUILD_FILES}" ]; then
+        failure "Some files were incorrectly put into the default build directory: ${DEFAULT_BUILD_FILES}"
+    fi
 
-	# NOTE: If adding new tests, add them above this CRLF test...
+    print_status "BUILD_DIR_BASE inside default build directory"
+    clean_build_dir
+    make BUILD_DIR_BASE=build/subdirectory || failure "Failed to build with BUILD_DIR_BASE as subdir"
+    NEW_BUILD_FILES=$(find ${BUILD}/subdirectory -type f)
+    if [ -z "${NEW_BUILD_FILES}" ]; then
+        failure "No files found in new build directory!"
+    fi
 
-	print_status "All tests completed"
-	if [ -n "${FAILURES}" ]; then
-		echo "Some failures were detected:"
-		echo -e "${FAILURES}"
-		exit 1
-	else
-		echo "Build tests passed."
-	fi
+    print_status "Parallel builds should work OK"
+    clean_build_dir
+    (make -j5 2>&1 | tee ${TESTDIR}/parallel_build.log) || failure "Failed to build in parallel"
+    if grep -q "warning: jobserver unavailable" ${TESTDIR}/parallel_build.log; then
+        failure "Parallel build prints 'warning: jobserver unavailable' errors"
+    fi
+
+    print_status "Can still clean build if all text files are CRLFs"
+    make clean || failure "Unexpected failure to make clean"
+    find . -exec unix2dos {} \; # CRLFify template dir
+    # make a copy of esp-idf and CRLFify it
+    CRLF_ESPIDF=${TESTDIR}/esp-idf-crlf
+    mkdir -p ${CRLF_ESPIDF}
+    cp -rv ${IDF_PATH}/* ${CRLF_ESPIDF}
+    # don't CRLFify executable files, as Linux will fail to execute them
+    find ${CRLF_ESPIDF} -type f ! -perm 755 -exec unix2dos {} \;
+    make IDF_PATH=${CRLF_ESPIDF} || failure "Failed to build with CRLFs in source"
+    # do the same checks we do for the clean build
+    assert_built ${APP_BINS} ${BOOTLOADER_BINS} partitions_singleapp.bin
+    [ -f ${BUILD}/partition*.bin ] || failure "A partition table should have been built in CRLF mode"
+
+
+    print_status "All tests completed"
+    if [ -n "${FAILURES}" ]; then
+        echo "Some failures were detected:"
+        echo -e "${FAILURES}"
+        exit 1
+    else
+        echo "Build tests passed."
+    fi
 }
 
 function print_status()
 {
-	echo "******** $1"
-	STATUS="$1"
+    echo "******** $1"
+    STATUS="$1"
 }
 
 function failure()
 {
-	echo "!!!!!!!!!!!!!!!!!!!"
-	echo "FAILURE: $1"
-	echo "!!!!!!!!!!!!!!!!!!!"
-	FAILURES="${FAILURES}${STATUS} :: $1\n"
+    echo "!!!!!!!!!!!!!!!!!!!"
+    echo "FAILURE: $1"
+    echo "!!!!!!!!!!!!!!!!!!!"
+    FAILURES="${FAILURES}${STATUS} :: $1\n"
 }
 
 TESTDIR=${TMP}/build_system_tests_$$
@@ -140,62 +179,68 @@ BUILD=${TESTDIR}/template/build
 # copy all the build output to a snapshot directory
 function take_build_snapshot()
 {
-	rm -rf ${SNAPSHOT}
-	cp -ap ${TESTDIR}/template/build ${SNAPSHOT}
+    rm -rf ${SNAPSHOT}
+    cp -ap ${TESTDIR}/template/build ${SNAPSHOT}
 }
 
 # verify that all the arguments are present in the build output directory
 function assert_built()
 {
-	until [ -z "$1" ]; do
-		if [ ! -f "${BUILD}/$1" ]; then
-			failure "File $1 should be in the build output directory"
-		fi
-		shift
-	done
+    until [ -z "$1" ]; do
+        if [ ! -f "${BUILD}/$1" ]; then
+            failure "File $1 should be in the build output directory"
+        fi
+        shift
+    done
 }
 
 # Test if a file has been rebuilt.
 function file_was_rebuilt()
 {
-	# can't use [ a -ot b ] here as -ot only gives second resolution
-	# but stat -c %y seems to be microsecond at least for tmpfs, ext4..
-	if [ "$(stat -c %y ${SNAPSHOT}/$1)" != "$(stat -c %y ${BUILD}/$1)" ]; then
-		return 0
-	else
-		return 1
-	fi
+    # can't use [ a -ot b ] here as -ot only gives second resolution
+    # but stat -c %y seems to be microsecond at least for tmpfs, ext4..
+    if [ "$(stat -c %y ${SNAPSHOT}/$1)" != "$(stat -c %y ${BUILD}/$1)" ]; then
+        return 0
+    else
+        return 1
+    fi
 }
 
 # verify all the arguments passed in were rebuilt relative to the snapshot
 function assert_rebuilt()
 {
-	until [ -z "$1" ]; do
-		assert_built "$1"
-		if [ ! -f "${SNAPSHOT}/$1" ]; then
-			failure "File $1 should have been original build snapshot"
-		fi
-		if ! file_was_rebuilt "$1"; then
-			failure "File $1 should have been rebuilt"
-		fi
-		shift
-	done
+    until [ -z "$1" ]; do
+        assert_built "$1"
+        if [ ! -f "${SNAPSHOT}/$1" ]; then
+            failure "File $1 should have been original build snapshot"
+        fi
+        if ! file_was_rebuilt "$1"; then
+            failure "File $1 should have been rebuilt"
+        fi
+        shift
+    done
 }
 
 # verify all the arguments are in the build directory & snapshot,
 # but were not rebuilt
 function assert_not_rebuilt()
 {
-	until [ -z "$1" ]; do
-		assert_built "$1"
-		if [ ! -f "${SNAPSHOT}/$1" ]; then
-			failure "File $1 should be in snapshot build directory"
-		fi
-		if file_was_rebuilt "$1"; then
-			failure "File $1 should not have been rebuilt"
-		fi
-		shift
-	done
+    until [ -z "$1" ]; do
+        assert_built "$1"
+        if [ ! -f "${SNAPSHOT}/$1" ]; then
+            failure "File $1 should be in snapshot build directory"
+        fi
+        if file_was_rebuilt "$1"; then
+            failure "File $1 should not have been rebuilt"
+        fi
+        shift
+    done
+}
+
+# do a "clean" that doesn't depend on 'make clean'
+function clean_build_dir()
+{
+    rm -rf --preserve-root ${BUILD}/*
 }
 
 cd ${TESTDIR}