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newlib: use nano.specs file when possible
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When using newlib_nano and a nano.specs file is present and the compiler
supports it, we use this file for letting the linker find the right
include paths. If not, we manually try to find the right newlib (nano)
paths.

When testing for the nano.specs file, we add -Werror so compilers which
don't support .specs files give the correct output.

When deriving the newlib include path from predefined directories or
from the compiler include path, we print a warning.

When none of the paths contain newlib.h, compilation fails.

When using newlib_nano is specified, and we can not find a newlib nano
directory, we print a warning that the regular newlib is used instead.
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Toon Stegen committed Jun 26, 2018
1 parent db6cb1a commit cef4189
Showing 1 changed file with 56 additions and 60 deletions.
116 changes: 56 additions & 60 deletions makefiles/libc/newlib.mk
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Original file line number Diff line number Diff line change
@@ -1,7 +1,8 @@
ifneq (,$(filter newlib_nano,$(USEMODULE)))
USE_NEWLIB_NANO = 1
# Test if nano.specs is available
ifeq ($(shell $(LINK) -specs=nano.specs -E - 2>/dev/null >/dev/null </dev/null ; echo $$?),0)
USE_NEWLIB_NANO = 1
ifeq ($(shell $(LINK) -Werror -specs=nano.specs -E - 2>/dev/null >/dev/null </dev/null ; echo $$?),0)
USE_NANO_SPECS_FILE = 1
ifeq ($(shell echo "int main(){} void _exit(int n) {(void)n;while(1);}" | LC_ALL=C $(CC) -xc - -o /dev/null -lc -specs=nano.specs -Wall -Wextra -pedantic 2>&1 | grep -q "use of wchar_t values across objects may fail" ; echo $$?),0)
CFLAGS += -fshort-wchar
LINKFLAGS += -Wl,--no-wchar-size-warning
Expand All @@ -13,71 +14,66 @@ ifneq (,$(filter newlib_gnu_source,$(USEMODULE)))
CFLAGS += -D_GNU_SOURCE=1
endif

ifeq (1,$(USE_NEWLIB_NANO))
export LINKFLAGS += -specs=nano.specs
endif

export LINKFLAGS += -lc

# Search for Newlib include directories
ifeq (1,$(USE_NANO_SPECS_FILE))
export LINKFLAGS += -specs=nano.specs
export CFLAGS += -specs=nano.specs
else
# Try to search for newlib in the standard search path of the compiler for includes
ifeq (,$(NEWLIB_INCLUDE_DIR))
COMPILER_INCLUDE_PATHS := $(shell $(PREFIX)gcc -v -x c -E /dev/null 2>&1 | grep '^\s' | tr -d '\n')
NEWLIB_INCLUDE_DIR := $(firstword $(dir $(wildcard $(addsuffix /newlib.h, $(COMPILER_INCLUDE_PATHS)))))
endif

# Try to search for newlib in the standard search path of the compiler for includes
ifeq (,$(NEWLIB_INCLUDE_DIR))
COMPILER_INCLUDE_PATHS := $(shell $(PREFIX)gcc -v -x c -E /dev/null 2>&1 | grep '^\s' | tr -d '\n')
NEWLIB_INCLUDE_DIR := $(firstword $(dir $(wildcard $(addsuffix /newlib.h, $(COMPILER_INCLUDE_PATHS)))))
endif
ifeq (,$(NEWLIB_INCLUDE_DIR))
$(warning newlib.h not found in compiler standard search path, looking in predefined directories)
# Ubuntu gcc-arm-embedded toolchain (https://launchpad.net/gcc-arm-embedded)
# places newlib headers in several places, but the primary source seem to be
# /etc/alternatives/gcc-arm-none-eabi-include
# Gentoo Linux crossdev place the newlib headers in /usr/arm-none-eabi/include
# Arch Linux also place the newlib headers in /usr/arm-none-eabi/include
# Ubuntu seem to put a copy of the newlib headers in the same place as
# Gentoo crossdev, but we prefer to look at /etc/alternatives first.
# On OSX, newlib includes are possibly located in
# /usr/local/opt/arm-none-eabi*/arm-none-eabi/include or /usr/local/opt/gcc-arm/arm-none-eabi/include
NEWLIB_INCLUDE_PATHS ?= \
/etc/alternatives/gcc-$(TARGET_ARCH)-include \
/usr/$(TARGET_ARCH)/include \
/usr/local/opt/$(TARGET_ARCH)*/$(TARGET_ARCH)/include \
/usr/local/opt/gcc-*/$(TARGET_ARCH)/include \
#

ifeq (,$(NEWLIB_INCLUDE_DIR))
# Since Clang is not installed as a separate instance for each crossdev target
# we need to tell it where to look for platform specific includes (Newlib
# headers instead of Linux/Glibc headers.)
# On GCC this is done when building the cross compiler toolchain so we do not
# actually need to specify the include paths for system includes.
# Ubuntu gcc-arm-embedded toolchain (https://launchpad.net/gcc-arm-embedded)
# places newlib headers in several places, but the primary source seem to be
# /etc/alternatives/gcc-arm-none-eabi-include
# Gentoo Linux crossdev place the newlib headers in /usr/arm-none-eabi/include
# Arch Linux also place the newlib headers in /usr/arm-none-eabi/include
# Ubuntu seem to put a copy of the newlib headers in the same place as
# Gentoo crossdev, but we prefer to look at /etc/alternatives first.
# On OSX, newlib includes are possibly located in
# /usr/local/opt/arm-none-eabi*/arm-none-eabi/include or /usr/local/opt/gcc-arm/arm-none-eabi/include
NEWLIB_INCLUDE_PATTERNS ?= \
/etc/alternatives/gcc-$(TARGET_ARCH)-include \
/usr/$(TARGET_ARCH)/include \
/usr/local/opt/$(TARGET_ARCH)*/$(TARGET_ARCH)/include \
/usr/local/opt/gcc-*/$(TARGET_ARCH)/include \
#
# Use the wildcard Makefile function to search for existing directories matching
# the patterns above. We use the -isystem gcc/clang argument to add the include
# directories as system include directories, which means they will not be
# searched until after all the project specific include directories (-I/path)
NEWLIB_INCLUDE_DIR ?= $(firstword $(dir $(wildcard $(addsuffix /newlib.h, $(NEWLIB_INCLUDE_PATTERNS)))))
endif
NEWLIB_INCLUDE_DIR ?= $(firstword $(dir $(wildcard $(addsuffix /newlib.h, $(NEWLIB_INCLUDE_PATHS)))))
endif

# If nothing was found we will try to fall back to searching for a cross-gcc in
# the current PATH and use a relative path for the includes
ifeq (,$(NEWLIB_INCLUDE_DIR))
NEWLIB_INCLUDE_DIR := $(abspath $(wildcard $(dir $(shell command -v $(PREFIX)gcc 2>/dev/null))/../$(TARGET_ARCH)/include))
endif
# If nothing was found we will try to fall back to searching for a cross-gcc in
# the current PATH and use a relative path for the includes
ifeq (,$(NEWLIB_INCLUDE_DIR))
$(warning newlib.h not found, guessing newlib include path from gcc path)
NEWLIB_INCLUDE_DIR := $(abspath $(wildcard $(dir $(shell command -v $(PREFIX)gcc 2>/dev/null))/../$(TARGET_ARCH)/include))
endif

ifeq ($(TOOLCHAIN),llvm)
# A cross GCC already knows the target libc include path (build-in at compile time)
# but Clang, when cross-compiling, needs to be told where to find the headers
# for the system being built.
# We also add -nostdinc to avoid including the host system headers by mistake
# in case some header is missing from the cross tool chain
NEWLIB_INCLUDES := -isystem $(NEWLIB_INCLUDE_DIR) -nostdinc
NEWLIB_INCLUDES += $(addprefix -isystem ,$(abspath $(wildcard $(dir $(NEWLIB_INCLUDE_DIR))/usr/include)))
endif
ifeq (,$(NEWLIB_INCLUDE_DIR))
$(error Could not find newlib include directory)
endif

ifeq (1,$(USE_NEWLIB_NANO))
NEWLIB_NANO_INCLUDE_DIR ?= $(firstword $(wildcard $(NEWLIB_INCLUDE_DIR)newlib-nano \
$(NEWLIB_INCLUDE_DIR)newlib/nano \
$(NEWLIB_INCLUDE_DIR)nano))
# newlib-nano overrides newlib.h and its include dir should therefore go before
# the regular system include dirs.
INCLUDES := -isystem $(NEWLIB_NANO_INCLUDE_DIR) $(INCLUDES)
# We use the -isystem gcc/clang argument to add the include
# directories as system include directories, which means they will not be
# searched until after all the project specific include directories (-I/path)
NEWLIB_INCLUDES := -isystem $(NEWLIB_INCLUDE_DIR)
NEWLIB_INCLUDES += $(addprefix -isystem ,$(abspath $(wildcard $(dir $(NEWLIB_INCLUDE_DIR))/usr/include)))
ifeq (1,$(USE_NEWLIB_NANO))
# newlib-nano include directory is called either newlib-nano or nano. Use the one we find first.
NEWLIB_NANO_INCLUDE_DIR ?= $(firstword $(wildcard $(addprefix $(NEWLIB_INCLUDE_DIR)/, newlib-nano newlib/nano nano)))
ifneq (,$(NEWLIB_NANO_INCLUDE_DIR))
# newlib-nano overrides newlib.h and its include dir
# should therefore go before the other newlib includes.
NEWLIB_INCLUDES := -isystem $(NEWLIB_NANO_INCLUDE_DIR) $(NEWLIB_INCLUDES)
else
$(warning Could not find newlib nano include dir, using normal newlib)
endif
endif
endif

# Newlib includes should go before GCC includes. This is especially important
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