Native and cross compile using GNU make, embedded C - c

Question

I'm working on a Makefile to make me able to native and cross-compile. choosing wether to compile for host linux or ti MSP432 should be done from command line:
$ make build PLATFORM=MSP432
$ make build PLATFORM=HOST
here's my Makefile that I tried to do it in:
include sources.mk
ifeq ($(PLATFORM),MSP432)
# Platform Overrides
# Architectures Specific Flags
LINKER_FILE = msp432p401r.lds
CPU = cortex-m4
ARCH = thumb
SPECS = nosys.specs
# Compiler Flags and Defines
CC = arm-none-eabi-gcc
LD = arm-none-eabi-ld
endif
ifeq ($(PLATFORM),HOST)
CC = gcc
endif
TARGET = c1m1
LDFLAGS = -Wl,-Map=$(TARGET).map -T $(LINKER_FILE)
CFLAGS = -mcpu=$(CPU) -m$(ARCH) --specs=$(SPECS) -Wall -Werror -g -O0
-std=c99
CPPFLAGs =
.PHONY: build
build: $(TARGET).out
.PHONY: clean
clean:
rm -f $(OBJS) $(TARGET).out $(TARGET).map
%.o : %.c
$(CC) -c $< $(CFLAGS) -o $#
OBJS = $(SOURCES:.c=.o)
$(TARGET).out: $(OBJS)
$(CC) $(OBJS) $(CFLAGS) $(LDFLAGS) -o $#
is this the right way to do that?
there's also another weird error happening when I compile using:
$ make main.o PLATFORM=MSP432
I get this error:
arm-none-eabi-gcc -c main.c -mcpu=cortex-m4 -mthumb --
specs=nosys.specs -Wall -Werror -g -O0 -std=c99 -o main.o
main.c:23:22: fatal error: platform.h: No such file or directory
#include "platform.h"
^
compilation terminated.
Makefile:64: recipe for target 'main.o' failed
make: *** [main.o] Error 1
and when I compile using this:
$ make main.o PLATFORM=HOST
I get this error, they are 2 different errors and I can't understand the reason behind this.
gcc -c main.c -mcpu= -m --specs= -Wall -Werror -g -O0 -std=c99 -o
main.o
gcc: warning: ‘-mcpu=’ is deprecated; use ‘-mtune=’ or ‘-march=’
instead
gcc: error: missing argument to ‘-mcpu=’
gcc: error: missing argument to ‘--specs=’
gcc: error: unrecognized command line option ‘-m’
Makefile:64: recipe for target 'main.o' failed
make: *** [main.o] Error 1
I posted those apparently different questions in 1 question, because I think they are affecting eachother.
this is also another headerfile that is called platform.h that has some conditionals to include some directives, which after the answer I think might be needed for compile time switches
#ifndef __PLATFORM_H__
#define __PLATFORM_H__
#if defined (MSP432)
#include "msp432p401r.h"
#define PRINTF(...)
#elif defined (HOST)
#include <stdio.h>
#define PRINTF(...) printf(__VA_ARGS__)
#else
#error "Platform provided is not supported in this Build System"
#endif
#endif /* __PLATFORM_H__ */

Answer 1

First, I will answer the case when PLATFORM and HOST are the same:
$ make main.o PLATFORM=HOST
I get this error, they are 2 different errors and I can't understand the reason behind this.
gcc -c main.c -mcpu= -m --specs= -Wall -Werror -g -O0 -std=c99 -o
main.o
gcc: warning: ‘-mcpu=’ is deprecated; use ‘-mtune=’ or ‘-march=’
instead
gcc: error: missing argument to ‘-mcpu=’
gcc: error: missing argument to ‘--specs=’
gcc: error: unrecognized command line option ‘-m’
Makefile:64: recipe for target 'main.o' failed
make: *** [main.o] Error 1
This is due to your makefile: CPU, ARCH and SPECS are only set when
PLATFORM is MSP432
So the line CFLAGS = -mcpu=$(CPU) -m$(ARCH) --specs=$(SPECS) -Wall -Werror -g -O0 -std=c99
is evalued as CFLAGS = -mcpu= -m --specs= -Wall -Werror -g -O0 -std=c99
When gcc is invoked with CFLAGS as argument, which is incorrect.
To correct this, you can make theses little changes in your makefile:
include sources.mk
ifeq ($(PLATFORM),MSP432)
# Platform Overrides
# Architectures Specific Flags
LINKER_FILE = msp432p401r.lds
CPU = cortex-m4
ARCH = thumb
SPECS = nosys.specs
LDFLAGS_ARCH = -T $(LINKER_FILE)
CFLAGS_ARCH = -mcpu=$(CPU) -m$(ARCH) --specs=$(SPECS)
# Compiler Flags and Defines
CC = arm-none-eabi-gcc
LD = arm-none-eabi-ld
endif
ifeq ($(PLATFORM),HOST)
CC = gcc
endif
TARGET = c1m1
LDFLAGS = -Wl,-Map=$(TARGET).map $(LDFLAGS_ARCH)
CFLAGS = $(CFLAGS_ARCH) -Wall -Werror -g -O0
-std=c99
CPPFLAGs =
Now, for the main.c:23:22: fatal error: platform.h: No such file or directory
You have to find where this file is locatted and eventually add it as a gcc option.
For instance, if the file platform.h is in /some/directory, you can add this
option to gcc to help it to find it:
-I/some/directory
So in makefile, you can have this line:
CFLAGS_ARCH = -mcpu=$(CPU) -m$(ARCH) --specs=$(SPECS) -I/some/directory
EDIT
In comments, you add this problem for your question:
that solved it the errors are consistent now, and here it is
In file included from main.c:23:0: ./include/common/platform.h:30:2: error:
#error "Platform provided is not supported in this Build System" #error "... *** [main.o] Error 1
Regarding the platform.h file, macro MSP432 or HOST must be defined in order to run.
To define such macro, the -D option must be passed to gcc.
So the idea is to add some line to the makefile to define MSP432 or HOST when necessary:
...
ifeq ($(PLATFORM),MSP432)
# Platform Overrides
# Architectures Specific Flags
LINKER_FILE = msp432p401r.lds
CPU = cortex-m4
ARCH = thumb
SPECS = nosys.specs
LDFLAGS_ARCH = -T $(LINKER_FILE)
CFLAGS_ARCH = -mcpu=$(CPU) -m$(ARCH) --specs=$(SPECS) -DMSP432
# Compiler Flags and Defines
CC = arm-none-eabi-gcc
LD = arm-none-eabi-ld
endif
ifeq ($(PLATFORM),HOST)
CFLAGS_ARCH = -DHOST
CC = gcc
endif
...