xref: /rk3399_ARM-atf/Makefile (revision 12f654b6a88f6f927fe34d00eece537b01f444e3)
1#
2# Copyright (c) 2013-2015, ARM Limited and Contributors. All rights reserved.
3#
4# Redistribution and use in source and binary forms, with or without
5# modification, are permitted provided that the following conditions are met:
6#
7# Redistributions of source code must retain the above copyright notice, this
8# list of conditions and the following disclaimer.
9#
10# Redistributions in binary form must reproduce the above copyright notice,
11# this list of conditions and the following disclaimer in the documentation
12# and/or other materials provided with the distribution.
13#
14# Neither the name of ARM nor the names of its contributors may be used
15# to endorse or promote products derived from this software without specific
16# prior written permission.
17#
18# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
22# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28# POSSIBILITY OF SUCH DAMAGE.
29#
30
31#
32# Trusted Firmware Version
33#
34VERSION_MAJOR			:= 1
35VERSION_MINOR			:= 1
36
37# Default goal is build all images
38.DEFAULT_GOAL			:= all
39
40include make_helpers/build_macros.mk
41
42################################################################################
43# Default values for build configurations
44################################################################################
45
46# Build verbosity
47V				:= 0
48# Debug build
49DEBUG				:= 0
50# Build platform
51DEFAULT_PLAT			:= fvp
52PLAT				:= ${DEFAULT_PLAT}
53# SPD choice
54SPD				:= none
55# Base commit to perform code check on
56BASE_COMMIT			:= origin/master
57# NS timer register save and restore
58NS_TIMER_SWITCH			:= 0
59# By default, Bl1 acts as the reset handler, not BL31
60RESET_TO_BL31			:= 0
61# Include FP registers in cpu context
62CTX_INCLUDE_FPREGS		:= 0
63# Determine the version of ARM GIC architecture to use for interrupt management
64# in EL3. The platform port can change this value if needed.
65ARM_GIC_ARCH			:= 2
66# Determine the version of ARM CCI product used in the platform. The platform
67# port can change this value if needed.
68ARM_CCI_PRODUCT_ID		:= 400
69# Flag used to indicate if ASM_ASSERTION should be enabled for the build.
70# This defaults to being present in DEBUG builds only.
71ASM_ASSERTION			:= ${DEBUG}
72# Build option to choose whether Trusted firmware uses Coherent memory or not.
73USE_COHERENT_MEM		:= 1
74# Flag used to choose the power state format viz Extended State-ID or the Original
75# format.
76PSCI_EXTENDED_STATE_ID		:= 0
77# Default FIP file name
78FIP_NAME			:= fip.bin
79# By default, use the -pedantic option in the gcc command line
80DISABLE_PEDANTIC		:= 0
81# Flags to generate the Chain of Trust
82GENERATE_COT			:= 0
83CREATE_KEYS			:= 1
84SAVE_KEYS			:= 0
85# Flags to build TF with Trusted Boot support
86TRUSTED_BOARD_BOOT		:= 0
87# By default, consider that the platform's reset address is not programmable.
88# The platform Makefile is free to override this value.
89PROGRAMMABLE_RESET_ADDRESS	:= 0
90# Build flag to treat usage of deprecated platform and framework APIs as error.
91ERROR_DEPRECATED		:= 0
92# By default, consider that the platform may release several CPUs out of reset.
93# The platform Makefile is free to override this value.
94COLD_BOOT_SINGLE_CPU		:= 0
95# Flag to introduce an infinite loop in BL1 just before it exits into the next
96# image. This is meant to help debugging the post-BL2 phase.
97SPIN_ON_BL1_EXIT		:= 0
98# Build PL011 UART driver in minimal generic UART mode
99PL011_GENERIC_UART		:= 0
100
101
102################################################################################
103# Checkpatch script options
104################################################################################
105
106CHECK_IGNORE		:=	--ignore COMPLEX_MACRO \
107				--ignore GERRIT_CHANGE_ID \
108				--ignore GIT_COMMIT_ID
109CHECKPATCH_ARGS		:=	--no-tree --no-signoff ${CHECK_IGNORE}
110CHECKCODE_ARGS		:=	--no-patch --no-tree --no-signoff ${CHECK_IGNORE}
111# Do not check the coding style on C library files
112CHECK_PATHS		:=	$(shell ls -I include -I lib) \
113				$(addprefix include/,$(shell ls -I stdlib include)) \
114				$(addprefix lib/,$(shell ls -I stdlib lib))
115
116
117################################################################################
118# Process build options
119################################################################################
120
121# Verbose flag
122ifeq (${V},0)
123        Q=@
124        CHECKCODE_ARGS	+=	--no-summary --terse
125else
126        Q=
127endif
128export Q
129
130# Process Debug flag
131$(eval $(call add_define,DEBUG))
132ifneq (${DEBUG}, 0)
133        BUILD_TYPE	:=	debug
134        CFLAGS		+= 	-g
135        ASFLAGS		+= 	-g -Wa,--gdwarf-2
136        # Use LOG_LEVEL_INFO by default for debug builds
137        LOG_LEVEL	:=	40
138else
139        BUILD_TYPE	:=	release
140        $(eval $(call add_define,NDEBUG))
141        # Use LOG_LEVEL_NOTICE by default for release builds
142        LOG_LEVEL	:=	20
143endif
144
145# Default build string (git branch and commit)
146ifeq (${BUILD_STRING},)
147        BUILD_STRING	:=	$(shell git log -n 1 --pretty=format:"%h")
148endif
149VERSION_STRING		:=	v${VERSION_MAJOR}.${VERSION_MINOR}(${BUILD_TYPE}):${BUILD_STRING}
150
151# The cert_create tool cannot generate certificates individually, so we use the
152# target 'certificates' to create them all
153ifneq (${GENERATE_COT},0)
154        FIP_DEPS += certificates
155endif
156
157
158################################################################################
159# Toolchain
160################################################################################
161
162CC			:=	${CROSS_COMPILE}gcc
163CPP			:=	${CROSS_COMPILE}cpp
164AS			:=	${CROSS_COMPILE}gcc
165AR			:=	${CROSS_COMPILE}ar
166LD			:=	${CROSS_COMPILE}ld
167OC			:=	${CROSS_COMPILE}objcopy
168OD			:=	${CROSS_COMPILE}objdump
169NM			:=	${CROSS_COMPILE}nm
170PP			:=	${CROSS_COMPILE}gcc -E
171
172ASFLAGS			+= 	-nostdinc -ffreestanding -Wa,--fatal-warnings	\
173				-Werror -Wmissing-include-dirs			\
174				-mgeneral-regs-only -D__ASSEMBLY__		\
175				${DEFINES} ${INCLUDES}
176CFLAGS			+= 	-nostdinc -ffreestanding -Wall			\
177				-Werror -Wmissing-include-dirs			\
178				-mgeneral-regs-only -mstrict-align		\
179				-std=c99 -c -Os					\
180				${DEFINES} ${INCLUDES}
181CFLAGS			+=	-ffunction-sections -fdata-sections
182
183LDFLAGS			+=	--fatal-warnings -O1
184LDFLAGS			+=	--gc-sections
185
186
187################################################################################
188# Common sources and include directories
189################################################################################
190
191BL_COMMON_SOURCES	+=	common/bl_common.c			\
192				common/tf_printf.c			\
193				common/aarch64/debug.S			\
194				lib/aarch64/cache_helpers.S		\
195				lib/aarch64/misc_helpers.S		\
196				lib/aarch64/xlat_helpers.c		\
197				lib/stdlib/std.c			\
198				plat/common/aarch64/platform_helpers.S
199
200INCLUDES		+=	-Iinclude/bl31			\
201				-Iinclude/bl31/services		\
202				-Iinclude/common		\
203				-Iinclude/drivers		\
204				-Iinclude/drivers/arm		\
205				-Iinclude/drivers/auth		\
206				-Iinclude/drivers/io		\
207				-Iinclude/drivers/ti/uart	\
208				-Iinclude/lib			\
209				-Iinclude/lib/aarch64		\
210				-Iinclude/lib/cpus/aarch64	\
211				-Iinclude/plat/common		\
212				-Iinclude/stdlib		\
213				-Iinclude/stdlib/sys		\
214				${PLAT_INCLUDES}		\
215				${SPD_INCLUDES}
216
217
218################################################################################
219# Generic definitions
220################################################################################
221
222BUILD_BASE		:=	./build
223BUILD_PLAT		:=	${BUILD_BASE}/${PLAT}/${BUILD_TYPE}
224
225PLAT_MAKEFILE		:=	platform.mk
226# Generate the platforms list by recursively searching for all directories
227# under /plat containing a PLAT_MAKEFILE. Append each platform with a `|`
228# char and strip out the final '|'.
229PLATFORMS		:=	$(shell find plat/ -name '${PLAT_MAKEFILE}' -print0 |			\
230					sed -r 's%[^\x00]*\/([^/]*)\/${PLAT_MAKEFILE}\x00%\1|%g' |	\
231					sed -r 's/\|$$//')
232SPDS			:=	$(shell ls -I none services/spd)
233
234# Platforms providing their own TBB makefile may override this value
235INCLUDE_TBBR_MK		:=	1
236
237
238################################################################################
239# Include SPD Makefile if one has been specified
240################################################################################
241
242ifneq (${SPD},none)
243ifdef EL3_PAYLOAD_BASE
244        $(warning "SPD and EL3_PAYLOAD_BASE are incompatible build options.")
245        $(warning "The SPD and its BL32 companion will be present but ignored.")
246endif
247        # We expect to locate an spd.mk under the specified SPD directory
248        SPD_MAKE	:=	$(shell m="services/spd/${SPD}/${SPD}.mk"; [ -f "$$m" ] && echo "$$m")
249
250        ifeq (${SPD_MAKE},)
251                $(error Error: No services/spd/${SPD}/${SPD}.mk located)
252        endif
253        $(info Including ${SPD_MAKE})
254        include ${SPD_MAKE}
255
256        # If there's BL32 companion for the chosen SPD, we expect that the SPD's
257        # Makefile would set NEED_BL32 to "yes". In this case, the build system
258        # supports two mutually exclusive options:
259        # * BL32 is built from source: then BL32_SOURCES must contain the list
260        #   of source files to build BL32
261        # * BL32 is a prebuilt binary: then BL32 must point to the image file
262        #   that will be included in the FIP
263        # If both BL32_SOURCES and BL32 are defined, the binary takes precedence
264        # over the sources.
265endif
266
267
268################################################################################
269# Include the platform specific Makefile after the SPD Makefile (the platform
270# makefile may use all previous definitions in this file)
271################################################################################
272
273ifeq (${PLAT},)
274        $(error "Error: Unknown platform. Please use PLAT=<platform name> to specify the platform")
275endif
276PLAT_MAKEFILE_FULL	:=	$(shell find plat/ -wholename '*/${PLAT}/${PLAT_MAKEFILE}')
277ifeq ($(PLAT_MAKEFILE_FULL),)
278        $(error "Error: Invalid platform. The following platforms are available: ${PLATFORMS}")
279endif
280
281include ${PLAT_MAKEFILE_FULL}
282
283# If the platform has not defined ENABLE_PLAT_COMPAT, then enable it by default
284ifndef ENABLE_PLAT_COMPAT
285ENABLE_PLAT_COMPAT := 1
286endif
287
288# Include the platform compatibility helpers for PSCI
289ifneq (${ENABLE_PLAT_COMPAT}, 0)
290include plat/compat/plat_compat.mk
291endif
292
293# Include the CPU specific operations makefile. By default all CPU errata
294# workarounds and CPU specifc optimisations are disabled. This can be
295# overridden by the platform.
296include lib/cpus/cpu-ops.mk
297
298
299################################################################################
300# Process platform overrideable behaviour
301################################################################################
302
303# Check if -pedantic option should be used
304ifeq (${DISABLE_PEDANTIC},0)
305        CFLAGS		+= 	-pedantic
306endif
307
308# Using the ARM Trusted Firmware BL2 implies that a BL3-3 image also need to be
309# supplied for the FIP and Certificate generation tools. This flag can be
310# overridden by the platform.
311ifdef BL2_SOURCES
312ifndef EL3_PAYLOAD_BASE
313NEED_BL33		?=	yes
314else
315# The BL33 image is not needed when booting an EL3 payload.
316NEED_BL33		:=	no
317endif
318endif
319
320# Process TBB related flags
321ifneq (${GENERATE_COT},0)
322        # Common cert_create options
323        ifneq (${CREATE_KEYS},0)
324                $(eval CRT_ARGS += -n)
325                ifneq (${SAVE_KEYS},0)
326                        $(eval CRT_ARGS += -k)
327                endif
328        endif
329        # Include TBBR makefile (unless the platform indicates otherwise)
330        ifeq (${INCLUDE_TBBR_MK},1)
331                include make_helpers/tbbr/tbbr_tools.mk
332        endif
333endif
334
335
336################################################################################
337# Auxiliary tools (fip_create, cert_create, etc)
338################################################################################
339
340# Variables for use with Certificate Generation Tool
341CRTTOOLPATH		?=	tools/cert_create
342CRTTOOL			?=	${CRTTOOLPATH}/cert_create
343
344# Variables for use with Firmware Image Package
345FIPTOOLPATH		?=	tools/fip_create
346FIPTOOL			?=	${FIPTOOLPATH}/fip_create
347
348
349################################################################################
350# Build options checks
351################################################################################
352
353$(eval $(call assert_boolean,DEBUG))
354$(eval $(call assert_boolean,NS_TIMER_SWITCH))
355$(eval $(call assert_boolean,RESET_TO_BL31))
356$(eval $(call assert_boolean,CTX_INCLUDE_FPREGS))
357$(eval $(call assert_boolean,ASM_ASSERTION))
358$(eval $(call assert_boolean,USE_COHERENT_MEM))
359$(eval $(call assert_boolean,DISABLE_PEDANTIC))
360$(eval $(call assert_boolean,GENERATE_COT))
361$(eval $(call assert_boolean,CREATE_KEYS))
362$(eval $(call assert_boolean,SAVE_KEYS))
363$(eval $(call assert_boolean,TRUSTED_BOARD_BOOT))
364$(eval $(call assert_boolean,PROGRAMMABLE_RESET_ADDRESS))
365$(eval $(call assert_boolean,COLD_BOOT_SINGLE_CPU))
366$(eval $(call assert_boolean,PSCI_EXTENDED_STATE_ID))
367$(eval $(call assert_boolean,ERROR_DEPRECATED))
368$(eval $(call assert_boolean,ENABLE_PLAT_COMPAT))
369$(eval $(call assert_boolean,SPIN_ON_BL1_EXIT))
370$(eval $(call assert_boolean,PL011_GENERIC_UART))
371
372
373################################################################################
374# Add definitions to the cpp preprocessor based on the current build options.
375# This is done after including the platform specific makefile to allow the
376# platform to overwrite the default options
377################################################################################
378
379$(eval $(call add_define,PLAT_${PLAT}))
380$(eval $(call add_define,NS_TIMER_SWITCH))
381$(eval $(call add_define,RESET_TO_BL31))
382$(eval $(call add_define,CTX_INCLUDE_FPREGS))
383$(eval $(call add_define,ARM_GIC_ARCH))
384$(eval $(call add_define,ARM_CCI_PRODUCT_ID))
385$(eval $(call add_define,ASM_ASSERTION))
386$(eval $(call add_define,LOG_LEVEL))
387$(eval $(call add_define,USE_COHERENT_MEM))
388$(eval $(call add_define,TRUSTED_BOARD_BOOT))
389$(eval $(call add_define,PROGRAMMABLE_RESET_ADDRESS))
390$(eval $(call add_define,COLD_BOOT_SINGLE_CPU))
391$(eval $(call add_define,PSCI_EXTENDED_STATE_ID))
392$(eval $(call add_define,ERROR_DEPRECATED))
393$(eval $(call add_define,ENABLE_PLAT_COMPAT))
394$(eval $(call add_define,SPIN_ON_BL1_EXIT))
395# Define the EL3_PAYLOAD_BASE flag only if it is provided.
396ifdef EL3_PAYLOAD_BASE
397$(eval $(call add_define,EL3_PAYLOAD_BASE))
398endif
399$(eval $(call add_define,PL011_GENERIC_UART))
400
401
402################################################################################
403# Include BL specific makefiles
404################################################################################
405
406ifdef BL1_SOURCES
407NEED_BL1 := yes
408include bl1/bl1.mk
409endif
410
411ifdef BL2_SOURCES
412NEED_BL2 := yes
413include bl2/bl2.mk
414endif
415
416ifdef BL31_SOURCES
417# When booting an EL3 payload, there is no need to compile the BL31 image nor
418# put it in the FIP.
419ifndef EL3_PAYLOAD_BASE
420NEED_BL31 := yes
421include bl31/bl31.mk
422endif
423endif
424
425
426################################################################################
427# Build targets
428################################################################################
429
430.PHONY:	all msg_start clean realclean distclean cscope locate-checkpatch checkcodebase checkpatch fiptool fip certtool
431.SUFFIXES:
432
433all: msg_start
434
435msg_start:
436	@echo "Building ${PLAT}"
437
438# Check if deprecated declarations should be treated as error or not.
439ifeq (${ERROR_DEPRECATED},0)
440    CFLAGS		+= 	-Wno-error=deprecated-declarations
441endif
442
443# Expand build macros for the different images
444ifeq (${NEED_BL1},yes)
445$(eval $(call MAKE_BL,1))
446endif
447
448ifeq (${NEED_BL2},yes)
449$(if ${BL2}, $(eval $(call MAKE_TOOL_ARGS,2,${BL2},in_fip)),\
450	$(eval $(call MAKE_BL,2,in_fip)))
451endif
452
453ifeq (${NEED_BL31},yes)
454BL31_SOURCES += ${SPD_SOURCES}
455$(if ${BL31}, $(eval $(call MAKE_TOOL_ARGS,31,${BL31},in_fip)),\
456	$(eval $(call MAKE_BL,31,in_fip)))
457endif
458
459# If a BL32 image is needed but neither BL32 nor BL32_SOURCES is defined, the
460# build system will call FIP_ADD_IMG to print a warning message and abort the
461# process. Note that the dependency on BL32 applies to the FIP only.
462ifeq (${NEED_BL32},yes)
463$(if ${BL32}, $(eval $(call MAKE_TOOL_ARGS,32,${BL32},in_fip)),\
464	$(if ${BL32_SOURCES}, $(eval $(call MAKE_BL,32,in_fip)),\
465		$(eval $(call FIP_ADD_IMG,BL32,--bl32))))
466endif
467
468# Add the BL33 image if required by the platform
469ifeq (${NEED_BL33},yes)
470$(eval $(call FIP_ADD_IMG,BL33,--bl33))
471endif
472
473locate-checkpatch:
474ifndef CHECKPATCH
475	$(error "Please set CHECKPATCH to point to the Linux checkpatch.pl file, eg: CHECKPATCH=../linux/script/checkpatch.pl")
476else
477ifeq (,$(wildcard ${CHECKPATCH}))
478	$(error "The file CHECKPATCH points to cannot be found, use eg: CHECKPATCH=../linux/script/checkpatch.pl")
479endif
480endif
481
482clean:
483	@echo "  CLEAN"
484	${Q}rm -rf ${BUILD_PLAT}
485	${Q}${MAKE} --no-print-directory -C ${FIPTOOLPATH} clean
486	${Q}${MAKE} PLAT=${PLAT} --no-print-directory -C ${CRTTOOLPATH} clean
487
488realclean distclean:
489	@echo "  REALCLEAN"
490	${Q}rm -rf ${BUILD_BASE}
491	${Q}rm -f ${CURDIR}/cscope.*
492	${Q}${MAKE} --no-print-directory -C ${FIPTOOLPATH} clean
493	${Q}${MAKE} PLAT=${PLAT} --no-print-directory -C ${CRTTOOLPATH} clean
494
495checkcodebase:		locate-checkpatch
496	@echo "  CHECKING STYLE"
497	@if test -d .git ; then	\
498		git ls-files | grep -v stdlib | while read GIT_FILE ; do ${CHECKPATCH} ${CHECKCODE_ARGS} -f $$GIT_FILE ; done ;	\
499	 else			\
500		 find . -type f -not -iwholename "*.git*" -not -iwholename "*build*" -not -iwholename "*stdlib*" -exec ${CHECKPATCH} ${CHECKCODE_ARGS} -f {} \; ;	\
501	 fi
502
503checkpatch:		locate-checkpatch
504	@echo "  CHECKING STYLE"
505	${Q}git log -p ${BASE_COMMIT}..HEAD -- ${CHECK_PATHS} | ${CHECKPATCH} ${CHECKPATCH_ARGS} - || true
506
507certtool: ${CRTTOOL}
508
509.PHONY: ${CRTTOOL}
510${CRTTOOL}:
511	${Q}${MAKE} PLAT=${PLAT} --no-print-directory -C ${CRTTOOLPATH}
512	@echo
513	@echo "Built $@ successfully"
514	@echo
515
516ifneq (${GENERATE_COT},0)
517certificates: ${CRT_DEPS} ${CRTTOOL}
518	${Q}${CRTTOOL} ${CRT_ARGS}
519	@echo
520	@echo "Built $@ successfully"
521	@echo "Certificates can be found in ${BUILD_PLAT}"
522	@echo
523endif
524
525${BUILD_PLAT}/${FIP_NAME}: ${FIP_DEPS} ${FIPTOOL}
526	${Q}${FIPTOOL} --dump ${FIP_ARGS} $@
527	@echo
528	@echo "Built $@ successfully"
529	@echo
530
531fiptool: ${FIPTOOL}
532fip: ${BUILD_PLAT}/${FIP_NAME}
533
534.PHONY: ${FIPTOOL}
535${FIPTOOL}:
536	${Q}${MAKE} --no-print-directory -C ${FIPTOOLPATH}
537
538cscope:
539	@echo "  CSCOPE"
540	${Q}find ${CURDIR} -name "*.[chsS]" > cscope.files
541	${Q}cscope -b -q -k
542
543help:
544	@echo "usage: ${MAKE} PLAT=<${PLATFORMS}> [OPTIONS] [TARGET]"
545	@echo ""
546	@echo "PLAT is used to specify which platform you wish to build."
547	@echo "If no platform is specified, PLAT defaults to: ${DEFAULT_PLAT}"
548	@echo ""
549	@echo "Please refer to the User Guide for a list of all supported options."
550	@echo "Note that the build system doesn't track dependencies for build "
551	@echo "options. Therefore, if any of the build options are changed "
552	@echo "from a previous build, a clean build must be performed."
553	@echo ""
554	@echo "Supported Targets:"
555	@echo "  all            Build all individual bootloader binaries"
556	@echo "  bl1            Build the BL1 binary"
557	@echo "  bl2            Build the BL2 binary"
558	@echo "  bl31           Build the BL3-1 binary"
559	@echo "  bl32           Build the BL3-2 binary"
560	@echo "  certificates   Build the certificates (requires 'GENERATE_COT=1')"
561	@echo "  fip            Build the Firmware Image Package (FIP)"
562	@echo "  checkcodebase  Check the coding style of the entire source tree"
563	@echo "  checkpatch     Check the coding style on changes in the current"
564	@echo "                 branch against BASE_COMMIT (default origin/master)"
565	@echo "  clean          Clean the build for the selected platform"
566	@echo "  cscope         Generate cscope index"
567	@echo "  distclean      Remove all build artifacts for all platforms"
568	@echo "  certtool       Build the Certificate generation tool"
569	@echo "  fiptool        Build the Firmware Image Package(FIP) creation tool"
570	@echo ""
571	@echo "Note: most build targets require PLAT to be set to a specific platform."
572	@echo ""
573	@echo "example: build all targets for the FVP platform:"
574	@echo "  CROSS_COMPILE=aarch64-none-elf- make PLAT=fvp all"
575