需要帮助理解 xv6 中的 Makefile

如何解决需要帮助理解 xv6 中的 Makefile

我一直在阅读 xv6 项目的 makefile。我想把所有的用户程序放到一个文件夹中，以保持项目的整洁。我找不到它在哪里编译用户程序。我知道当我运行时： make fs.img;它将编译用户程序，但我找不到任何命令来这样做。我还希望所有内核代码都进入一个名为“kernel”的目录。
make 中是否有允许自动编译的功能，或者只是我没有看到的东西。任何人都可以建议任何 make 文档来帮助我理解这个 makefile。

我的 Makefile：

OBJS = \
    bio.o\
    console.o\
    exec.o\
    file.o\
    fs.o\
    ide.o\
    ioapic.o\
    kalloc.o\
    kbd.o\
    lapic.o\
    log.o\
    main.o\
    mp.o\
    picirq.o\
    pipe.o\
    proc.o\
    sleeplock.o\
    spinlock.o\
    string.o\
    swtch.o\
    syscall.o\
    sysfile.o\
    sysproc.o\
    trapasm.o\
    trap.o\
    uart.o\
    vectors.o\
    vm.o\

# Cross-compiling (e.g.,on Mac OS X)
# TOOLPREFIX = i386-jos-elf

# Using native tools (e.g.,on X86 Linux)
#TOOLPREFIX = 

# Try to infer the correct TOOLPREFIX if not set
ifndef TOOLPREFIX
TOOLPREFIX := $(shell if i386-jos-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/dev/null 2>&1; \
    then echo 'i386-jos-elf-'; \
    elif objdump -i 2>&1 | grep 'elf32-i386' >/dev/null 2>&1; \
    then echo ''; \
    else echo "***" 1>&2; \
    echo "*** Error: Couldn't find an i386-*-elf version of GCC/binutils." 1>&2; \
    echo "*** Is the directory with i386-jos-elf-gcc in your PATH?" 1>&2; \
    echo "*** If your i386-*-elf toolchain is installed with a command" 1>&2; \
    echo "*** prefix other than 'i386-jos-elf-',set your TOOLPREFIX" 1>&2; \
    echo "*** environment variable to that prefix and run 'make' again." 1>&2; \
    echo "*** To turn off this error,run 'gmake TOOLPREFIX= ...'." 1>&2; \
    echo "***" 1>&2; exit 1; fi)
endif

# If the makefile can't find QEMU,specify its path here
# QEMU = qemu-system-i386

# Try to infer the correct QEMU
ifndef QEMU
QEMU = $(shell if which qemu > /dev/null; \
    then echo qemu; exit; \
    elif which qemu-system-i386 > /dev/null; \
    then echo qemu-system-i386; exit; \
    elif which qemu-system-x86_64 > /dev/null; \
    then echo qemu-system-x86_64; exit; \
    else \
    qemu=/Applications/Q.app/Contents/MacOS/i386-softmmu.app/Contents/MacOS/i386-softmmu; \
    if test -x $$qemu; then echo $$qemu; exit; fi; fi; \
    echo "***" 1>&2; \
    echo "*** Error: Couldn't find a working QEMU executable." 1>&2; \
    echo "*** Is the directory containing the qemu binary in your PATH" 1>&2; \
    echo "*** or have you tried setting the QEMU variable in Makefile?" 1>&2; \
    echo "***" 1>&2; exit 1)
endif

CC = $(TOOLPREFIX)gcc
AS = $(TOOLPREFIX)gas
LD = $(TOOLPREFIX)ld
OBJcopY = $(TOOLPREFIX)objcopy
OBJDUMP = $(TOOLPREFIX)objdump
CFLAGS = -fno-pic -static -fno-builtin -fno-strict-aliasing -O2 -Wall -MD -ggdb -m32 -Werror -fno-omit-frame-pointer
CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
ASFLAGS = -m32 -gdwarf-2 -Wa,-divide
# FreeBSD ld wants ``elf_i386_fbsd''
LDFLAGS += -m $(shell $(LD) -V | grep elf_i386 2>/dev/null | head -n 1)

# disable PIE when possible (for Ubuntu 16.10 toolchain)
ifneq ($(shell $(CC) -dumpspecs 2>/dev/null | grep -e '[^f]no-pie'),)
CFLAGS += -fno-pie -no-pie
endif
ifneq ($(shell $(CC) -dumpspecs 2>/dev/null | grep -e '[^f]nopie'),)
CFLAGS += -fno-pie -nopie
endif

xv6.img: bootblock kernel
    dd if=/dev/zero of=xv6.img count=10000
    dd if=bootblock of=xv6.img conv=notrunc
    dd if=kernel of=xv6.img seek=1 conv=notrunc
#
xv6memfs.img: bootblock kernelmemfs
    dd if=/dev/zero of=xv6memfs.img count=10000
    dd if=bootblock of=xv6memfs.img conv=notrunc
    dd if=kernelmemfs of=xv6memfs.img seek=1 conv=notrunc
#
bootblock: bootasm.S bootmain.c
    $(CC) $(CFLAGS) -fno-pic -O -nostdinc -I. -c bootmain.c
    $(CC) $(CFLAGS) -fno-pic -nostdinc -I. -c bootasm.S
    $(LD) $(LDFLAGS) -N -e start -Ttext 0x7C00 -o bootblock.o bootasm.o bootmain.o
    $(OBJDUMP) -S bootblock.o > bootblock.asm
    $(OBJcopY) -S -O binary -j .text bootblock.o bootblock
    ./sign.pl bootblock
#
entryother: entryother.S
    $(CC) $(CFLAGS) -fno-pic -nostdinc -I. -c entryother.S
    $(LD) $(LDFLAGS) -N -e start -Ttext 0x7000 -o bootblockother.o entryother.o
    $(OBJcopY) -S -O binary -j .text bootblockother.o entryother
    $(OBJDUMP) -S bootblockother.o > entryother.asm
#
initcode: initcode.S
    $(CC) $(CFLAGS) -nostdinc -I. -c initcode.S
    $(LD) $(LDFLAGS) -N -e start -Ttext 0 -o initcode.out initcode.o
    $(OBJcopY) -S -O binary initcode.out initcode
    $(OBJDUMP) -S initcode.o > initcode.asm

kernel: $(OBJS) entry.o entryother initcode kernel.ld
    $(LD) $(LDFLAGS) -T kernel.ld -o kernel entry.o $(OBJS) -b binary initcode entryother
    $(OBJDUMP) -S kernel > kernel.asm
    $(OBJDUMP) -t kernel | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > kernel.sym

# kernelmemfs is a copy of kernel that maintains the
# disk image in memory instead of writing to a disk.
# This is not so useful for testing persistent storage or
# exploring disk buffering implementations,but it is
# great for testing the kernel on real hardware without
# needing a scratch disk.

#MEMFSOBJS = $(filter-out ide.o,$(OBJS)) memide.o
#kernelmemfs: $(MEMFSOBJS) entry.o entryother initcode kernel.ld fs.img
#   $(LD) $(LDFLAGS) -T kernel.ld -o kernelmemfs entry.o  $(MEMFSOBJS) -b binary initcode entryother fs.img
#   $(OBJDUMP) -S kernelmemfs > kernelmemfs.asm
#   $(OBJDUMP) -t kernelmemfs | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > kernelmemfs.sym
#
#tags: $(OBJS) entryother.S _init
#   etags *.S *.c

vectors.S: vectors.pl
    ./vectors.pl > vectors.S

ULIB = ulib.o usys.o printf.o umalloc.o

#
_%: %.o $(ULIB)
    $(LD) $(LDFLAGS) -N -e main -Ttext 0 -o $@ $^
    $(OBJDUMP) -S $@ > $*.asm
    $(OBJDUMP) -t $@ | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $*.sym

_forktest: forktest.o $(ULIB)
    # forktest has less library code linked in - needs to be small
    # in order to be able to max out the proc table.
    $(LD) $(LDFLAGS) -N -e main -Ttext 0 -o _forktest forktest.o ulib.o usys.o
    $(OBJDUMP) -S _forktest > forktest.asm

mkfs: mkfs.c fs.h
    gcc -Werror -Wall -o mkfs mkfs.c

# Prevent deletion of intermediate files,e.g. cat.o,after first build,so
# that disk image changes after first build are persistent until clean.  More
# details:
# http://www.gnu.org/software/make/manual/html_node/Chained-Rules.html
.PRECIoUS: %.o

UPROGS=\
    _cat\
    _echo\
    _forktest\
    _grep\
    _init\
    _kill\
    _ln\
    _ls\
    _mkdir\
    _rm\
    _sh\
    _stressfs\
    _usertests\
    _wc\
    _zombie\
    _login\
    _cp\
    _head\
    _bedit\
    _clear\
    _tail\
    _sleep\
    _date\


fs.img: mkfs README $(UPROGS)
    ./mkfs fs.img README $(UPROGS) simple.txt

-include *.d

clean: 
    rm -f *.tex *.dvi *.idx *.aux *.log *.ind *.ilg \
    *.o *.d *.asm *.sym vectors.S bootblock entryother \
    initcode initcode.out kernel xv6.img fs.img kernelmemfs \
    xv6memfs.img mkfs .gdbinit \
    $(UPROGS)

# make a printout
FILES = $(shell grep -v '^\#' runoff.list)
PRINT = runoff.list runoff.spec README toc.hdr toc.ftr $(FILES)

#xv6.pdf: $(PRINT)
#   ./runoff
#   ls -l xv6.pdf

#print: xv6.pdf

# run in emulators

#bochs : fs.img xv6.img
#   if [ ! -e .bochsrc ]; then ln -s dot-bochsrc .bochsrc; fi
#   bochs -q

# try to generate a unique GDB port
GDBPORT = $(shell expr `id -u` % 5000 + 25000)
# QEMU's gdb stub command line changed in 0.11
QEMUGDB = $(shell if $(QEMU) -help | grep -q '^-gdb'; \
    then echo "-gdb tcp::$(GDBPORT)"; \
    else echo "-s -p $(GDBPORT)"; fi)
ifndef cpuS
cpuS := 2
endif
QEMUOPTS = -drive file=fs.img,index=1,media=disk,format=raw -drive file=xv6.img,index=0,format=raw -smp $(cpuS) -m 512 $(QEMUEXTRA)

qemu: fs.img xv6.img
    $(QEMU) -serial mon:stdio $(QEMUOPTS)

#qemu-memfs: xv6memfs.img
#   $(QEMU) -drive file=xv6memfs.img,format=raw -smp $(cpuS) -m 256

#qemu-nox: fs.img xv6.img
#   $(QEMU) -nographic $(QEMUOPTS)

#.gdbinit: .gdbinit.tmpl
#   sed "s/localhost:1234/localhost:$(GDBPORT)/" < $^ > $@

#qemu-gdb: fs.img xv6.img .gdbinit
#   @echo "*** Now run 'gdb'." 1>&2
#   $(QEMU) -serial mon:stdio $(QEMUOPTS) -S $(QEMUGDB)

#qemu-nox-gdb: fs.img xv6.img .gdbinit
#   @echo "*** Now run 'gdb'." 1>&2
#   $(QEMU) -nographic $(QEMUOPTS) -S $(QEMUGDB)

# CUT HERE
# prepare dist for students
# after running make dist,probably want to
# rename it to rev0 or rev1 or so on and then
# check in that version.

EXTRA=\
    mkfs.c ulib.c user.h cat.c echo.c forktest.c grep.c kill.c\
    ln.c ls.c mkdir.c rm.c stressfs.c usertests.c wc.c zombie.c\
    printf.c umalloc.c\
    README dot-bochsrc *.pl toc.* runoff runoff1 runoff.list\
    .gdbinit.tmpl gdbutil\

dist:
    rm -rf dist
    mkdir dist
    for i in $(FILES); \
    do \
        grep -v PAGEBREAK $$i >dist/$$i; \
    done
    sed '/CUT HERE/,$$d' Makefile >dist/Makefile
    echo >dist/runoff.spec
    cp $(EXTRA) dist

dist-test:
    rm -rf dist
    make dist
    rm -rf dist-test
    mkdir dist-test
    cp dist/* dist-test
    cd dist-test; $(MAKE) print
    cd dist-test; $(MAKE) bochs || true
    cd dist-test; $(MAKE) qemu

# update this rule (change rev#) when it is time to
# make a new revision.
#tar:
#   rm -rf /tmp/xv6
#   mkdir -p /tmp/xv6
#   cp dist/* dist/.gdbinit.tmpl /tmp/xv6
#   (cd /tmp; tar cf - xv6) | gzip >xv6-rev10.tar.gz  # the next one will be 10 (9/17)
#

.PHONY: dist-test dist

编辑： 我想要做的是将我所有的 UPROGS 程序放入一个名为 Programs 的目录中。我将如何更改 makefile 以这样做。

解决方法

所有 make 系统（根据 POSIX 的要求）都有许多内置规则，包括知道如何从 C 文件编译目标文件的规则。

有关 GNU make 内置规则的信息，您可以review the manual。