Introduction

The Build System section contains information on subjects such as the GCC Compiler and Build Environment.

Overload Directory

A project can replace any NetBurner system file with a local copy. Place the copy under a directory named overload in the project root, at the path the system file has relative to $(NNDK_ROOT). The build system finds it by name. No makefile change is required.

Three lines in $(NNDK_ROOT)/make/boilerplate.mk implement this:

Line	What it does
LOCAL_OVERLOAD_DIR ?= overload	Names the directory. A project makefile can override it, but no example does.
NBINCLUDE := $(subst $(NNDK_ROOT),$(LOCAL_OVERLOAD_DIR),$(NBINCLUDE)) $(NBINCLUDE)	Rewrites every -I$(NNDK_ROOT)/... entry into an -Ioverload/... entry and puts the rewritten list first, so an overloaded header is found before the system copy.
VPATH := $(LOCAL_OVERLOAD_DIR) $(NNDK_ROOT)	Makes the pattern rules resolve an overloaded .c, .cpp, or .s before the system copy. Library source paths are stripped of their $(NNDK_ROOT)/ prefix first, so VPATH can search both trees.

The build also preprocesses predef.h through the same include path to see whether the project enabled NBRTOS_STACKOVERFLOW or NBRTOS_STACKUNDERFLOW. If so, it adds -fstack-check to CPPFLAGS and DBCPPFLAGS automatically.

Note: The directory must be named overload, not override. The first time you add a file to it, run make clean so the system library is rebuilt against the new file.

For how to use the feature, including the predef-overload.h shortcut for system configuration, see Modifying System Files with Overload and Overload Directory. A working project is at Overload Directory & System Files.

GCC Compiler Flags

Compiler flags can be added or modified in both NBEclipse and command line makefiles.

Generic

Language	Mode	Flag	Description
C/C++	R, D	-gdwarf-2	Adds dwarf-2 debug symbols to the binary. This makes it easier to resolve symbols in gdb.
C/C++	R, D	-Wall	Enables all warnings.
C/C++	R, D	-Werror=return-type	Treats warnings as errors for functions that are missing a return statement.
C/C++	R, D	-Wno-unused	Suppresses warnings for unused variables.
C/C++	R, D	-falign-functions=4	Aligns functions to 4-byte boundaries for improved performance.
C/C++	R	-O2	Enables level 2 optimization for improved performance.
C/C++	D	-O0	Disables optimization for debugging.
C/C++	R, D	-D PLATFORM_NAME=$(PLATFORM_NAME)	Defines the PLATFORM_NAME macro with the value of the PLATFORM_NAME environment variable.
C/C++	R, D	$(NBINCLUDE)	Includes the specified directories in the search path for header files.
C	R, D	-std=gnu17	Sets the C standard to GNU C17.
C	R, D	-ffunction-sections	Places each function in a separate section to enable linker optimizations.
C	R, D	-fdata-sections	Places each data object in a separate section to enable linker optimizations.
C++	R, D	-std=gnu++17	Sets the C++ standard to GNU C++17.
C++	R, D	-fno-rtti	Disables runtime type information (RTTI) for improved performance.
C++	R, D	-fno-exceptions	Disables C++ exceptions for improved performance.
C++	R, D	-Wno-register	Suppresses warnings for unused register variables.
C++	R, D	-ffunction-sections	Places each function in a separate section to enable linker optimizations.
C++	R, D	-fdata-sections	Places each data object in a separate section to enable linker optimizations.
Assembler	R, D	$(CPUFLAG)	Specifies the CPU architecture flag.

Architecture-Specific Compiler Flags

ARM Cortex-M7

Language	Mode	Flag	Description
C/C++	R, D	-fasynchronous-unwind-tables	Enables asynchronous unwind tables
C/C++	R, D	-D_C11_SOURCE	Defines the _C11_SOURCE macro.
C/C++	R, D	-DCORTEX_M7	Defines the CORTEX_M7 macro.

ARM Cortex-M0+

Language	Mode	Flag	Description
C/C++	R, D	-fasynchronous-unwind-tables	Enables asynchronous unwind tables
C/C++	D	-fomit-frame-pointer	Omit frame pointer for improved performance.
C/C++	R, D	-D_C11_SOURCE	Defines the _C11_SOURCE macro.
C/C++	R, D	-DCORTEX_M0PLUS	Defines the CORTEX_M0PLUS macro.

ColdFire

Language	Mode	Flag	Description
C/C++	R, D	-fno-omit-frame-pointer	Do not omit frame pointer for improved debugging
C/C++	R, D	-fasynchronous-unwind-tables	Enables asynchronous unwind tables
C/C++	R, D	-DCOLDFIRE	Defines the COLDFIRE macro
Assembler	D	--defsym _DEBUG=1	Defines the _DEBUG symbol.

CPU-Specific Compiler Flags

SAME70

Language	Mode	Flag	Description
C/C++	R, D	-mcpu=cortex-m7	Specifies the CPU architecture.
C/C++	R, D	-mthumb	Specifies the Thumb instruction set.
C/C++	R, D	-mfpu=fpv5-d16	Specifies the floating-point unit.
C/C++	R, D	-mfloat-abi=$(ABI_OPT)	Specifies the floating-point ABI. Defaults to softfp
C/C++	R, D	-D$(CPU)	Defines the $(CPU) macro.
C++	R, D	-fno-use-cxa-atexit	Disables the use of __cxa_atexit
C++	R, D	-falign-fuinctions=4	Aligns functions to 4-byte boundaries for improved performance.

MIMXRT11xx, MIMXRT10xx

Language	Mode	Flag	Description
C/C++	R, D	-mcpu=cortex-m7	Specifies the CPU architecture.
C/C++	R, D	-mthumb	Specifies the Thumb instruction set.
C/C++	R, D	-mfpu=fpv5-d16	Specifies the floating-point unit.
C/C++	R, D	-mfloat-abi=$(ABI_OPT)	Specifies the floating-point ABI. Defaults to softfp
C/C++	R, D	-D$(CPU)	Defines the $(CPU) macro.
C++	R, D	-fno-use-cxa-atexit	Disables the use of __cxa_atexit
C++	R, D	-falign-fuinctions=8	Aligns functions to 8-byte boundaries for improved performance.

SAMD20

Language	Mode	Flag	Description
C/C++	R, D	-mcpu=cortex-m0plus	Specifies the CPU architecture.
C/C++	R, D	-mthumb	Specifies the Thumb instruction set.
C++	R	-fno-use-cxa-atexit	Disables the use of __cxa_atexit
C++	R	-falign-fuinctions=4	Aligns functions to 4-byte boundaries for improved performance.

MCF5441X

Language	Mode	Flag	Description
C/C++	R, D	-D$(CPU)	Defines the $(CPU) macro.
C/C++	R, D	-mcpu=54415	Specifies the CPU architecture.

Platform-Specific Compiler Flags

MODM7AE70

Language	Mode	Flag	Description
C/C++	R, D	-D__SAME70Q21__	Defines the __SAME70Q21__ macro.
C/C++	R, D	-DMODM7AE70	Defines the MODM7AE70 macro.

SBE70LC

Language	Mode	Flag	Description
C/C++	R, D	-D__SAME70Q21__	Defines the __SAME70Q21__ macro.
C/C++	R, D	-DSBE70LC	Defines the SBE70LC macro.

SOMRT1061

Language	Mode	Flag	Description
C/C++	R, D	-D__MIMXRT106xx__	Defines the __MIMXRT106xx__ macro.
C/C++	R, D	-D__MIMXRT1061__	Defines the __MIMXRT1061__ macro.
C/C++	R, D	-DSOMRT1061	Defines the SOMRT1061 macro.

MOD5441X

Language	Mode	Flag	Description
C/C++	R, D	-DMOD5441X	Defines the MOD5441X macro.

NANO54415

Language	Mode	Flag	Description
C/C++	R, D	-DNANO54415	Defines the NANO54415 macro.

SB800EX

Language	Mode	Flag	Description
C/C++	R, D	-DSB800EX	Defines the SB800EX macro.

Linker Flags

Generic

Flag	Description
$(CPUFLAG)	Specifies the CPU architecture flag.
-Wl,-n	Disables linking to dyn
-T$(NNDK_ROOT)/platform/$(PLATFORM)/lib/$(PLATFORM).ld	Specifies the linker script.
-Wl,-R$(NNDK_ROOT)/platform/$(PLATFORM)/lib/sys.ld	Specifies the linker script.
-Wl,-Map=$(@:.elf=.map)	Generates a map file.
-Wl,--cref	Generates a cross-reference table.
-Wl,--gc-sections	Removes unused sections to reduce the size of the binary.
-Wl,--start-group,$(NBLIBS) $(XTRALIB) -lstdc++ -lc -Wl,--end-group	Specifies the libraries to link.

Architecture-Specific Linker Flags

None

CPU-Specific Linker Flags

SAME70

Flag	Description
-nostartfiles	Disables linking to the default startup files.
-mfloat-abi=$(ABI_OPT)	Specifies the floating-point ABI. Defaults to softfp
-Wl--thumb-entry=Reset_Handler	Specifies the entry point.
-Wl--thumb-entry=_start_	Specifies the entry point. (SOMRT1061)

MIMXRT11xx, MIMXRT10xx

Flag	Description
-nostartfiles	Disables linking to the default startup files.
-mfloat-abi=$(ABI_OPT)	Specifies the floating-point ABI. Defaults to softfp
-Wl--thumb-entry=Reset_Handler	Specifies the entry point.

SAMD20

Flag	Description
-nostartfiles	Disables linking to the default startup files.
-Wl--thumb-entry=Reset_Handler	Specifies the entry point.

MCF5441X

None

Platform-Specific Linker Flags

None

Pack Binary

Generic

None

Architecture-Specific

None

CPU-Specific

MCF5441X

Executable	I/O	Flag	Description
m68k-elf-objcopy	.elf -> .s19	-O srec	Converts the elf file to s19
m68k-elf-objcopy	.elf -> .s19	-Wl,--gc-sections	Removes unused sections to reduce the size of the binary.
m68k-elf-objcopy	.elf -> .s19	--strip-all	Removes all symbols from the binary.
compcode	.s19 -> _APP.s19	-M $(^:.s19=.map)	Specifies the map file.
compcode	.s19 -> _APP.s19	-R	Print report.
compcode	.s19 -> _APP.s19	-P$(PLATFORM)	Specifies the platform.
compcode	.s19 -> .bin	-O binary	Converts the s19 file to binary
compcode	.s19 -> .bin	-M $(^:.s19=.map)	Specifies the map file.
compcode	.s19 -> .bin	-B	Specifies binary output.
compcode	.s19 -> .bin	-P$(PLATFORM)	Specifies the platform.
compcode	.s19 -> .bin	-R	Print report.

SAMD20

Executable	I/O	Flag	Description
nbfspack	.elf -> .bin	-output-target bin	Converts the elf file to binary

SAME70

Executable	I/O	Flag	Description
arm-none-eabi-size	.elf -> .bin		Displays the size of the binary.
nbfspack	.elf -> .bin	-output-target bin	Converts the elf file to binary
nbfspack	.elf -> .bin	-S	Show build statistics.
nbfspack	.elf -> .bin	-P $(PLATFORM)	Specifies the platform.

MIMXRT11xx, MIMXRT10xx

Executable	I/O	Flag	Description
nbfspack	.elf -> .bin	-output-target bin	Converts the elf file to binary

Platform-Specific

MODM7AE70

Executable	I/O	Flag	Description
nbfspack	.elf -> .bin	-C	Compress program sections
nbfspack	.elf -> .bin	-cflag S:3	.
nbfspack	.elf -> .bin	-cflag S:0	.
nbfspack	.elf -> .bin	-cflag S:1	.

SBE70LC

Executable	I/O	Flag	Description
nbfspack	.elf -> .bin	-C	Compress program sections
nbfspack	.elf -> .bin	-cflag S:3	.
nbfspack	.elf -> .bin	-cflag S:0	.
nbfspack	.elf -> .bin	-cflag S:1	.

SOMRT1061

None

MOD5441X

Executable	I/O	Flag	Description
compcode	.s19 -> .bin	0xC0040000 0xC1FC0000	Application address range.

NANO54415

Executable	I/O	Flag	Description
compcode	.s19 -> .bin	0x04000 0x800000	Application address range.

SB800EX

Executable	I/O	Flag	Description
compcode	.s19 -> .bin	0x04000 0x800000	Application address range.