I was trying to compile some code written in c and c++ for an atmega32u4.
I wrote a makefile from information gathered from the internet, but it fails for some reason.
If I run the commands separately from the command line, they all work. However running the make command gives the following error:
main.cpp:3:10: fatal error: avr/io.h: No such file or directory
The contents of the main.cpp file are not really relevant, it's just a blink code.
The makefile looks like this:
all: init clean $(patsubst %.cpp, %.hex, $(wildcard *.cpp))
avr-size -A $(BUILDPATH)/*.elf
%.c.o: %.c
#mkdir -p $(BUILDPATH)
avr-gcc -c -g -Os -w -mmcu=$(CHIP) $^ -o $(BUILDPATH)/$#
%.cpp.o: %.cpp
#mkdir -p $(BUILDPATH)
avr-g++ -c -g -Os -w -mmcu=$(CHIP) $^ -o $(BUILDPATH)/$#
%.elf: %.o
avr-gcc -g -Os -w -mmcu=$(CHIP) $(BUILDPATH)/$^ -o $(BUILDPATH)/$#
%.hex: %.elf
avr-objcopy -R .eeprom --change-section-lma .eeprom=0 -O ihex $(BUILDPATH)/$^ $(BUILDPATH)/$#
So what am I doing wrong? Do I have to set up some environment variables or is the structure of the makefile incorrect?
Related
I was trying to compile statically cpp-netlib and rpclib for ARM device.(Same as ZEDboard)
Everything i did is changed the compiler and system settings in CMakeLists.txt file.
set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)
set(CMAKE_SYSROOT /home/a/buildroot-2018.05/output/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/)
set(tools /home/a/buildroot-2018.05/output/host/bin/)
set(CMAKE_C_COMPILER ${tools}arm-buildroot-linux-uclibcgnueabihf-gcc)
set(CMAKE_CXX_COMPILER ${tools}arm-buildroot-linux-uclibcgnueabihf-g++)
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
After Makefile is created by cmake i ran make and no output has been produced. As i understand build directories should appear.
For the rpclib things went better. It has compiled the librpc.a file but unftunately its not linking to my program.
arm-buildroot-linux-uclibcgnueabihf-g++ -I/home/a/rpclib/include/ -Xlinker -static /home/a/rpclib/librpc.a main.cpp
produces this output:
/home/a/buildroot-2018.05/output/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/../../../../arm-buildroot-linux-uclibcgnueabihf/bin/ld: cannot find -lgcc_s
/home/a/buildroot-2018.05/output/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/../../../../arm-buildroot-linux-uclibcgnueabihf/bin/ld: cannot find -lgcc_s
collect2: error: ld returned 1 exit status
but there is gcc_s in the sysroot directory.
~/buildroot-2018.05/output/host/arm-buildroot-linux-uclibcgnueabihf$ find ./ -name *gcc_s*
./sysroot/lib/libgcc_s.so
./sysroot/lib/libgcc_s.so.1
./sysroot/usr/include/boost/asio/detail/gcc_sync_fenced_block.hpp
./sysroot/usr/include/boost/atomic/detail/caps_gcc_sync.hpp
./sysroot/usr/include/boost/atomic/detail/ops_gcc_sync.hpp
./sysroot/usr/include/boost/atomic/detail/ops_gcc_sparc.hpp
./sysroot/usr/include/boost/atomic/detail/caps_gcc_sparc.hpp
./sysroot/usr/include/boost/smart_ptr/detail/sp_counted_base_gcc_sparc.hpp
./lib/libgcc_s.so
./lib/libgcc_s.so.1
I guess i am missing something important about cross-compilation.
So basically i have 3 questions:
Can you suggest some resources about cross-compilation for embdedd devices?
How to compile cpp-netlib?
How to link already compiled librpc?
Actually buildroot supports building static libraries.
Steps to build a custom library using buildroot:
Create a folder inside buildroot/package folder with the name of target library.
e.g. my path looks like this /home/a/buildroot-2018.05/package/rpclib
Create Config.in file in target library dir with the needed parameters which can be checked in buildroot manual or better
Create [package-name].mk
Then add entry in /buildroot/package/Config.in
Then package can be marked for installation in menuconfig/target pacckages
My Config.in file for rpclib
config BR2_PACKAGE_RPCLIB
bool "rpclib"
depends on BR2_INSTALL_LIBSTDCPP
depends on BR2_USE_WCHAR
help
rpclib is a modern C++ msgpack-RPC server and client library
http://rpclib.net
My rpclib.mk file
RPCLIB_VERSION = v2.2.1
RPCLIB_SITE = $(call github,rpclib,rpclib,$(RPCLIB_VERSION))
RPCLIB_INSTALL_STAGING = YES
RPCLIB_INSTALL_TARGET = NO
RPCLIB_CONF_OPTS = -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=OFF
$(eval $(cmake-package))
And entry in Config.in in the buildroot/packages dir
source "package/rpclib/Config.in"
After executing make i received
./output/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/usr/lib/librpc.a
Working in my little beatle (https://gitlab.com/melviso1/beatle) I have a custom makefile for building rpclib without using cmake stuff (I apologize but I really hate cmake and similar tools). Maybe that can help.
Put it in the root of rpclib for building, clean or install. Please review tabs in the following script, because my pasting here can make some loses.
I used this to compile rpclib inside arm. For cross-compiling you could edit and change build tools.
CXXFLAGS=-std=c++0x -O3 -pthread -DASIO_STANDALONE -DRPCLIB_ASIO=clmdep_asio -DRPCLIB_FMT=clmdep_fmt -DRPCLIB_MSGPACK=clmdep_msgpack -Wall
INCLUDE=-Iinclude -I./dependencies/include
OBJS=obj/format.o obj/posix.o obj/client.o obj/client_error.o obj/response.o obj/server_session.o obj/dispatcher.o obj/optional.o obj/rpc_error.o obj/server.o obj/this_handler.o obj/this_server.o obj/this_session.o
all: obj librpc.a
obj:
mkdir -p obj
librpc.a: $(OBJS)
ar -r -s librpc.a $(OBJS)
obj/format.o: dependencies/src/format.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./dependencies/src/format.cc -o obj/format.o
obj/posix.o: dependencies/src/posix.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./dependencies/src/posix.cc -o obj/posix.o
obj/client.o: lib/rpc/client.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./lib/rpc/client.cc -o obj/client.o
obj/client_error.o: lib/rpc/detail/client_error.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./lib/rpc/detail/client_error.cc -o obj/client_error.o
obj/response.o: lib/rpc/detail/response.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./lib/rpc/detail/response.cc -o obj/response.o
obj/server_session.o: lib/rpc/detail/server_session.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./lib/rpc/detail/server_session.cc -o obj/server_session.o
obj/dispatcher.o: lib/rpc/dispatcher.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./lib/rpc/dispatcher.cc -o obj/dispatcher.o
obj/optional.o: lib/rpc/nonstd/optional.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
obj/rpc_error.o: lib/rpc/rpc_error.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
obj/server.o: lib/rpc/server.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
obj/this_handler.o: ./lib/rpc/this_handler.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
obj/this_server.o: lib/rpc/this_server.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
obj/this_session.o: ./lib/rpc/this_session.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
install:
cp -rf include/rpc /usr/local/include/
cp librpc.a /usr/local/lib/
uninstall:
rm -rf /usr/local/include/rpc
rm /usr/local/lib/librpc.a
clean:
rm -f librpc.a
rm -f obj/*
.PHONY: obj clean install uninstall`
I have following folder structure
--Makefile
--source/
--boot.s
--kernel.c
--linker.ld
--build/
and I compile my sources using following Makefile
###############################################################################
#
# A makefile script for generation of raspberry pi kernel images.
#
###############################################################################
# The toolchain to use. arm-none-eabi works, but there does exist
CC = arm-none-eabi-gcc
LD = arm-none-eabi-gcc
# The intermediate directory for compiled object files.
BUILD = build/
# The directory in which source files are stored.
SOURCE = source/
CFLAGS = -march=armv8-a+crc \
-mcpu=cortex-a53 \
-mtune=cortex-a53 \
-mfpu=crypto-neon-fp-armv8 \
-mfloat-abi=hard \
-ftree-vectorize \
-funsafe-math-optimizations \
-O2 -pipe -ffreestanding
LDFLAGS = -T $(SOURCE)linker.ld -ffreestanding -O2 -nostdlib
# The name of the output file to generate.
TARGET = kernel.img
.PHONY: all clean run
# Rule to make everything.
all: $(TARGET)
# Rule to remake everything. Does not include clean.
rebuild: clean all
#Rule to invoke qemu
run:
qemu-system-arm -m 256 -M raspi2 -serial stdio -kernel $(BUILD)kernel.elf
$(TARGET): kernel.elf
arm-none-eabi-objcopy $(BUILD)kernel.elf -O binary $(BUILD)kernel.img
kernel.elf: boot.o kernel.o
$(LD) $(LDFLAGS) -o $(BUILD)kernel.elf $(BUILD)boot.o $(BUILD)kernel.o
boot.o: $(SOURCE)boot.s
$(CC) $(CFLAGS) -c $(SOURCE)boot.s -o $(BUILD)boot.o
kernel.o: $(SOURCE)boot.s
$(CC) $(CFLAGS) -c $(SOURCE)kernel.c -o $(BUILD)kernel.o
# Rule to clean files.
clean :
-rm -f $(BUILD)*
-rm -f *.o
-rm -f *.elf
-rm -f *.img
How to write pattern based rules ? I tried many stack overflow answers but couldn't make it work.
First I listed my source using wild cards but couldn't write proper target as sources list had [source/boot.s source/kernel.c] and it would create object files in source folder it self.
I was facing difficulty while keeping sources and build directory different. Any help is appreciated.
----------Complete solution as per #MadScientist -----------
###############################################################################
#
# A makefile script for generation of raspberry pi kernel images.
#
###############################################################################
# The toolchain to use. arm-none-eabi works, but there does exist
CC = arm-none-eabi-gcc
LD = arm-none-eabi-gcc
# The intermediate directory for compiled object files.
BUILD = build/
# The directory in which source files are stored.
SOURCE = source/
CFLAGS = -march=armv8-a+crc \
-mcpu=cortex-a53 \
-mtune=cortex-a53 \
-mfpu=crypto-neon-fp-armv8 \
-mfloat-abi=hard \
-ftree-vectorize \
-funsafe-math-optimizations \
-O2 -pipe -ffreestanding
LDFLAGS = -T $(SOURCE)linker.ld -ffreestanding -O2 -nostdlib
SOURCES := $(wildcard $(SOURCE)*.s) $(wildcard $(SOURCE)*.c)
OBJECTS := $(patsubst $(SOURCE)%,$(BUILD)%.o,$(basename $(SOURCES)))
# The name of the output file to generate.
TARGET = kernel.img
.PHONY: all clean run
# Rule to make everything.
all: $(BUILD)$(TARGET)
# Rule to remake everything. Does not include clean.
rebuild: clean all
#Rule to invoke qemu
run:
qemu-system-arm -m 256 -M raspi2 -serial stdio -kernel $(BUILD)kernel.elf
$(BUILD)%.o : $(SOURCE)%.s
$(CC) $(CFLAGS) -c $< -o $#
$(BUILD)%.o : $(SOURCE)%.c
$(CC) $(CFLAGS) -c $< -o $#
$(BUILD)$(TARGET): $(BUILD)kernel.elf
arm-none-eabi-objcopy $< -O binary $#
$(BUILD)kernel.elf: $(OBJECTS)
$(LD) $(LDFLAGS) -o $# $^
# Rule to clean files.
clean :
-rm -f $(BUILD)*
-rm -f *.o
-rm -f *.elf
-rm -f *.img
This is wrong:
boot.o: $(SOURCE)boot.s
$(CC) $(CFLAGS) -c $(SOURCE)boot.s -o $(BUILD)boot.o
You are telling make that your recipe will build a file named boot.o, but it doesn't: it creates a file named $(BUILD)boot.o, which is completely different. Same with your rules to build kernel.img and kernel.elf.
If you want to write a pattern rule the % can match only identical parts. Since SOURCE and BUILD are not identical, they won't match the % part. So you have to write this:
$(BUILD)%.o : $(SOURCE)%.s
$(CC) $(CFLAGS) -c $< -o $#
Since you're building $(BUILD)xxx.o you have to use that as a prerequisite as well, so you have to write:
$(BUILD)$(TARGET): $(BUILD)kernel.elf
arm-none-eabi-objcopy $< -O binary $#
$(BUILD)kernel.elf: $(BUILD)boot.o $(BUILD)kernel.o
$(LD) $(LDFLAGS) -o $# $^
ETA
If you want to get the source files via wildcard you can, but you have to substitute the directory as well not just the suffix, like this:
SOURCES := $(wildcard $(SOURCE)*.s)
OBJECTS := $(patsubst $(SOURCE)%.s,$(BUILD)%.o,$(SOURCES))
If you have both assembly and C source files (you didn't show any C source files in your example makefile) you can use this:
SOURCES := $(wildcard $(SOURCE)*.s) $(wildcard $(SOURCE)*.c)
OBJECTS := $(patsubst $(SOURCE)%,$(BUILD)%.o,$(basename $(SOURCES)))
I am trying to understand makefile.
I took atmega168 bootloader's makefile and simplified it to this:
CC = avr-gcc
override CFLAGS = -g -Wall -Os -mmcu=atmega328p -DF_CPU=16000000L '-DMAX_TIME_COUNT=F_CPU>>4' '-DNUM_LED_FLASHES=1' -DBAUD_RATE=57600
atmega328: ATmegaBOOT_168_atmega328.hex
%.elf: ATmegaBOOT_168.o
avr-gcc -g -Wall -Os -mmcu=atmega328p -DF_CPU=16000000L '-DMAX_TIME_COUNT=F_CPU>>4' '-DNUM_LED_FLASHES=1' -DBAUD_RATE=57600 -Wl,--section-start=.text=0x7800 -o $# $<
clean:
rm -rf *.o *.elf *.lst *.map *.sym *.lss *.eep *.srec *.bin *.hex
%.hex: %.elf
avr-objcopy -j .text -j .data -O ihex $< $#
When I ran $ make atmega328 I get:
avr-gcc -g -Wall -Os -mmcu=atmega328p -DF_CPU=16000000L '-DMAX_TIME_COUNT=F_CPU>>4' '-DNUM_LED_FLASHES=1' -DBAUD_RATE=57600 -c -o ATmegaBOOT_168.o ATmegaBOOT_168.c
avr-gcc -g -Wall -Os -mmcu=atmega328p -DF_CPU=16000000L '-DMAX_TIME_COUNT=F_CPU>>4' '-DNUM_LED_FLASHES=1' -DBAUD_RATE=57600 -Wl,--section-start=.text=0x7800 -o ATmegaBOOT_168_atmega328.elf ATmegaBOOT_168.o
avr-objcopy -j .text -j .data -O ihex ATmegaBOOT_168_atmega328.elf ATmegaBOOT_168_atmega328.hex
rm ATmegaBOOT_168_atmega328.elf ATmegaBOOT_168.o
Why cannot I remove CC or CFLAGS?
I understand some basics of makefile. I read a lot on the internet, plus went through gnu manual, but I cannot understand the very first output with ATmegaBOOT_168.c. What/How has generated first command?
Was there used some second makefile? If yes, how to find its location?
UPDATE:
If I rename ATmegaBOOT_168.c to ATmegaBOOT_1681.c. Running $ make atmega328 gives:
make: *** No rule to make target 'ATmegaBOOT_168_atmega328.hex', needed by 'atmega328'. Stop.
but the rule is present.
CC and CFLAGS are variables used in the built in implicit rules of GNU make. When you run make, it reads your makefile a bit like:
No target given, so we'll make the first: atmega328. This requires a .hex file.
The .hex file can be generated from a .elf file per the last rule.
.elf files can be generated by the %.elf rule (which here looks like you've broken the pattern, as there's no % in the dependencies).
There's no rule for .o in this file, so the default recipe $(CC) $(CPPFLAGS) $(CFLAGS) -c is used. Since a .c file is found, this rule is applicable and generates the first command. The rule could have been written (as shown in suffix rules):
.c.o:
$(CC) -c $(CFLAGS) $(CPPFLAGS) -o $# $<
Backtrack up this list, now that the source has been found, and run the commands.
If the implicit rule variables are left unset, you will typically get programs built for your host system using cc.
I'm working with a project using flex/bison and trying to compile it using make. The lex.yy.c, tab.c, tab.h from flex/bison are generated correctly and placed in the obj directory. However, there is an error when trying to compile the obj/lex.yy.c file and it cannot resolve an include to a file in the src/frontend directory. Any ideas where I am going wrong? Makefile and output included below.
Makefile:
VPATH = src obj src/frontend src/interpreter
SRCS = lex.yy.c C.tab.c symbol_table.c nodes.c print_ast.c interpreter.c main.c
OBJS := $(SRCS:%.c=obj/%.o)
INCLUDES = -Isrc -Iobj -Isrc/frontend -Isrc/interpreter
CPPFLAGS = -Wall
LDFLAGS = -Wall
CC = gcc
LEX = flex
YACC = bison -d -t -v
all: bin/mycc
bin/mycc: $(OBJS)
$(CC) -g $(LDFLAGS) $(INCLUDES) -o $# $^
obj/lex.yy.c: C.flex obj/C.tab.h
$(LEX) -o $# $<
obj/C.tab.c: C.y
$(YACC) -o $# $<
obj/C.tab.h: obj/C.tab.c
#touch $#
obj/%.o: src/%.c
$(CC) -g $(CPPFLAGS) $(INCLUDES) -c $^
clean:
rm $(OBJS) obj/lex.yy.c obj/C.tab.c obj/C.tab.h
depend:
$(CC) -M $(SRCS) > .deps
cat Makefile .deps > makefile
Output:
bison -d -t -v -o obj/C.tab.c src/frontend/C.y
src/frontend/C.y: conflicts: 4 shift/reduce, 14 reduce/reduce
src/frontend/C.y:248.11-53: warning: rule useless in parser due to conflicts: external_declaration: function_definition
flex -o obj/lex.yy.c src/frontend/C.flex
gcc -Wall -c -o obj/lex.yy.o obj/lex.yy.c
src/frontend/C.flex:13:19: fatal error: token.h: No such file or directory
#include "token.h"
^
compilation terminated.
make: *** [obj/lex.yy.o] Error 1
The problem is that you define your -I flags for compiling in the variable $(INCLUDES) instead of in the normal $(CPPFLAGS). As a result, when the default rule for compiling C files runs, it does not use any of those -I flags and so the compiler can't find the include files. You can see the command line for the compiler in your output.
To fix it, get rid of the INCLUDES = line and add all of them to CPPFLAGS:
CPPFLAGS = -Wall -Isrc -Iobj -Isrc/frontend -Isrc/interpreter
I am trying to add a project's (call it b) code to a different project(call it a). Both projects are compile and run separately. I just copied the folder of project b into project a's folder. In project a's Makefile, I added the lines to compile project b with it. It compiles fine. Now I want to use b's code. But when I try to #include "/bfolder/somefile.h", it cannot find the file. What am I missing about this? If I can just #include "somefileinsamedirectory.h", why can't I do #include "/bfolder/somefile.h"?`
This is a 's Makefile that I have edited to include the irobot_driver code.
INCLUDE = -I/usr/X11R6/include -I/home/sterling/irobot_driver
CC=g++
CFLAGS=-w -D LINUX -fpermissive
CFLAGS_R= -w -D LINUX -O3 -fpermissive
CFLAGS_D=-w -D LINUX -fpermissive
OBJ= obj
OBJ_DEBUG= obj_debug
OBJDIR= release
SRCDIR= src
LDFLAGS= -L/usr/X11R6/lib$(LIBSELECT) -lGL -lfltk -lfltk_gl -lXext -lX11 -lglut -lGLU -lfltk_images
SOURCES_RAW=codeprofiler.cpp gametimer.cpp timer.cpp timeprofile.cpp vector4.cpp matrix.cpp agent.cpp agentcontroller.cpp dummy.cpp evader.cpp pursuer.cpp goal.cpp player.cpp graphdata.cpp graph.cpp cubiccoefs.cpp segment.cpp trajectory.cpp anode.cpp arrayvector4.cpp color.cpp drawcomponent.cpp drawcontroller.cpp flags.cpp global.cpp map_analyzer.cpp minheap.cpp node.cpp quadtree.cpp queue.cpp results.cpp sensor.cpp settings.cpp utility.cpp world.cpp gui.cpp main.cpp logger.cpp parameters.cpp counter.cpp polygon.cpp line.cpp
TARGET:= pursuit_evasion
TARGETD:= pursuit_evasion_d
TARGETP:= pursuit_evasion_p
TARGETW32:= pursuit_evasion_w32
OBJECTS:=$(SOURCES_RAW:.cpp=.o)
OBJECTS:=$(patsubst %.o,$(OBJDIR)/%.o, $(OBJECTS))
SOURCES:=$(SOURCES_RAW)
SOURCES:=$(patsubst %.cpp,$(SRCDIR)/%.cpp, $(SOURCES))
OBJ_DEBUG:=$(SOURCES_RAW:.cpp=.o)
OBJ_DEBUG:=$(patsubst %.o,debug/%.o, $(OBJ_DEBUG))
OBJECTS_P:=$(SOURCES_RAW:.cpp=.o)
OBJECTS_P:=$(patsubst %.o,profile/%.o, $(OBJECTS_P))
OBJDIR=obj
all: $(TARGET)
#--- Release
$(TARGET): $(OBJECTS)
$(CC) -w -D LINUX $(INCLUDE) $^ -o $# $(LDFLAGS)
cd /home/sterling/irobot_driver; sudo make -j2
release/%.o: src/%.cpp
$(CC) -c $< $(CFLAGS_R) -o $#
#--- Debug
debug: $(TARGETD)
$(TARGETD): $(OBJ_DEBUG)
$(CC) -w -D LINUX $(INCLUDE) $^ -o $# $(LDFLAGS)
cd /home/sterling/irobot_driver; sudo make -j2
debug/%.o: src/%.cpp
$(CC) -c -g $< $(CFLAGS)-o $#
#-- Profile
profile: $(TARGETP)
$(TARGETP): $(OBJECTS_P)
$(CC) -w -g -pg -D LINUX $(INCLUDE) $^ -o $# $(LDFLAGS)
profile/%.o: src/%.cpp
$(CC) -c -g -pg $< $(CFLAGS)-o $#
win32: $(TARGETW32)
$(TARGETW32): $(OBJECTS)
$(CC) -w -D WIN32 $(INCLUDE_W32) $^ -o $# $(LDFLAGS)
.PHONY : clean
clean:
rm -f release/*.o
rm -f debug/*.o
rm -f profile/*.o
rm -f $(TARGET) $(TARGETD) $(TARGETP)
cd /home/sterling/irobot_driver; make clean;
The #include "/the/whole/path/to/a/file" that works is -
#include "/home/sterling/irobot_driver/robot_driver_agent.h"
You can, but when you declare the path starting with /some/path/to/file.h it's going to really look for the file at /some/path/to/file.h. If instead you want the bfolder/somefile.h, remove the / from the beginning.
Also, in general, if b is a library that you want to use, it is best to keep it in whatever folder it resides, and include and link using the -I, -L and -l options of gcc, or similar options of other compilers. This way, if you update b you don't need to copy it to every project that uses it.
Try
#include "bfolder/somefile.h"
You are including a leading slash in "/bfolder/somefile.h", which means /bfolder would be in the root directory.
#include "/bfolder/..." would be implying that bfolder is in the root directory of your computer's file system. If bfolder is in the same directory as your source code, then you would just want #include "bfolder/somefile.h"