Makefile does not “see” %.o %.asm rule

问题

I'm writing a project and wanted to make one, good makefile. At some point I noticed that it doesn't work for multiple .asm files, I did some research and modified my file, so it looks like this:

PROJDIRS := kernel lib
ASMFILES := $(shell find $(PROJDIRS) -type f -name "*.asm")
SRCFILES := $(shell find $(PROJDIRS) -type f -name "*.c")
HDRFILES := $(shell find $(PROJDIRS) -type f -name "*.h")

ASMOBJCT := $(patsubst %.asm,%.o,$(ASMFILES))
OBJFILES := $(patsubst %.c,%.o,$(SRCFILES))
TSTFILES := $(patsubst %.c,%_t,$(SRCFILES))

DEPFILES    := $(patsubst %.c,%.d,$(SRCFILES))
TSTDEPFILES := $(patsubst %,%.d,$(TSTFILES))

WARNINGS := -Wall -Wextra -pedantic

NASM=nasm
CC=/usr/local/cross/bin/i686-elf-gcc
CFLAGS=-nostdlib -nostdinc -ffreestanding -O2 $(WARNINGS) -masm=intel -Iinclude -std=c99
LDFLAGS=-T link.ld -nostdlib -ffreestanding -O2 -lgcc
ASFLAGS=-felf

all: $(OBJFILES) link

clean:
    -rm kernel/*.o
    -rm kernel/hal/*.o
    -rm _bin_/*.elf

link:
    /usr/local/cross/bin/i686-elf-gcc $(LDFLAGS) $(OBJFILES) $(ASMOBJCT) -o _bin_/kernel.elf

%.o: %.c
    $(CC) $(CFLAGS) $< -c -o $@

%.o: %.asm
    $(NASM) $(ASFLAGS) $< -o $@

But for some reason the last one does not execute, as a result linker throws an error that required object files are not found. I have no idea what am I doing wrong. Do you have any idea how do I fix this weird issue?

回答1:

You never tell make to build them.

Your default rule is all: $(OBJFILES) link which tells to build everything in $(OBJFILES) and the link target. This doesn't include anything in $(ASMOBJCT) so when link goes to use them they don't exist.

You can fix this by putting the actual prereqs for the link target on the link: line like so:

link: $(OBJFILES) $(ASMOBJCT)

and then use $^ (all prereqs) instead of $(OBJFILES) $(ASMOBJCT) on the linking line.

You could then drop $(OBJFILES) from the all target prereq list since you won't need it there anymore.

You could also replace link with _bin_/kernel.elf on the all target line and then in the link: target line and then use -o '$@' (rule target) on the linking line instead of writing it out.

来源：https://stackoverflow.com/questions/25435416/makefile-does-not-see-o-asm-rule

标签

makefile

nasm