Linux下的make命令使用心得

make menuconfig 是执行makefile里面的menuconfig目标.
如果后面ARCH =arm CROSS_COMPILE=arm-linux-的话表明： 编译出来的目标是针对ARM体系结构的。因为是针对ARM体系结构，所以需要使用交叉编译器。使用CROSS_COMPILE=xxx来指定交叉编译器。
CROSS_COMPILE=arm-linux- 意思是制定交叉编译器为arm-linux-XXX。 如：makefile里面会指定CC为arm-linux-gcc。

本文译至：http://d.hatena.ne.jp/embedded/20140829/p1

为了使make命令执行并行处理，-j 选项可以用来指定作业数。

$ make -j4 

作业数是在编译的时候指定主机的CPU个数，所以在脚本中写成一个常量很糟糕。（特别是把编译脚本给其他人的时候。）并行处理的作业数和编译的效率直接相关，所以需要设置合适的作业数量。

昨天的文章中在编译perf时，make的任务数能自动设置成CPU的数量。调查了一下它是怎么做的。

linux/tools/perf/Makefile

#
# Do a parallel build with multiple jobs, based on the number of CPUs online
# in this system: 'make -j8' on a 8-CPU system, etc.
#
# (To override it, run 'make JOBS=1' and similar.)
#
ifeq ($(JOBS),)
  JOBS := $(shell grep -c ^processor /proc/cpuinfo 2>/dev/null)
  ifeq ($(JOBS),)
    JOBS := 1
  endif
endif

这种计算了/proc/cpuinfo以processor开头的行的数量。

这里不使用wc命令来计算匹配的行数，而是用grep -c来获取。

这里JOBS是CPU的个数，用这个变量在子进程中使用make命令。

$(MAKE) -f Makefile.perf --no-print-directory -j$(JOBS) O=$(FULL_O) $(SET_DEBUG) $@

关于make时，通过-j参数指定多线程数目
 
之前在折腾crosstool-ng：
【记录】crosstool为xscale编译(ct-ng build)过程
时，就偶尔看到别人用
ct-ng build.4
意思是多线程去编译
估计底层就是调用的makefile的支持多线程的这个功能。
后来又在别处看到类似的写法了：
Introduction to Cross Compilation
中的：
   
   
   
   

    
    
    
    
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- uImage -j4
   
   
   
   

此时，才想到，去查查make的参数：
（此处是在cygwin中）
   
   
   
   

    
    
    
    
Administrator@PC-20130611GART /cygdrive/e/Dev_Root
$ make --help
Usage: make [options] [target] ...
Options:
  -b, -m                      Ignored for compatibility.
  -B, --always- make           Unconditionally make all targets.
  -C DIRECTORY, --directory=DIRECTORY
                              Change to DIRECTORY before doing anything.
  -d                          Print lots of debugging information.
  --debug[=FLAGS]             Print various types of debugging information.
  -e, --environment-overrides
                              Environment variables override makefiles.
  -- eval =STRING               Evaluate STRING as a makefile statement.
  -f FILE, -- file =FILE, --makefile=FILE
                              Read FILE as a makefile.
  -h, --help                  Print this message and exit .
  -i, --ignore-errors         Ignore errors from recipes.
  -I DIRECTORY, --include- dir =DIRECTORY
                              Search DIRECTORY for included makefiles.
  -j [N], --jobs[=N]          Allow N jobs at once; infinite jobs with no arg.
  -k, --keep-going            Keep going when some targets can't be made.
  -l [N], --load-average[=N], --max-load[=N]
                              Don't start multiple jobs unless load is below N.
  -L, --check- symlink - times   Use the latest mtime between symlinks and target.
  -n, --just-print, --dry-run, --recon
                              Don't actually run any recipe; just print them.
  -o FILE, --old- file =FILE, --assume-old=FILE
                              Consider FILE to be very old and don't remake it.
  -p, --print-data-base       Print make 's internal database.
  -q, --question              Run no recipe; exit status says if up to date .
  -r, --no- builtin -rules      Disable the built- in implicit rules.
  -R, --no- builtin -variables  Disable the built- in variable settings.
  -s, --silent, --quiet       Don't echo recipes.
  -S, --no-keep-going, --stop
                              Turns off -k.
  -t, -- touch                 Touch targets instead of remaking them.
  --trace                     Print tracing information.
  - v , --version               Print the version number of make and exit .
  -w, --print-directory       Print the current directory.
  --no-print-directory        Turn off -w, even if it was turned on implicitly.
  -W FILE, --what- if =FILE, --new- file =FILE, --assume-new=FILE
                              Consider FILE to be infinitely new.
  --warn-undefined-variables  Warn when an undefined variable is referenced.

This program built for i686-pc-cygwin
Report bugs to make @gnu.org>

Administrator@PC-20130611GART /cygdrive/e/Dev_Root
$
   
   
   
   
果然对应的-j==–jobs，指的是多线程的意思：
   
   
   
   

    
    
    
    

     
     
     
     

      
      
      
      
-j
 [N], –jobs[=N] Allow N jobs at once; infinite jobs with no arg.
     
     
     
     
    
    
    
    
   
   
   
   
用法即：
   
   
   
   

    
    
    
    
make –j 4
   
   
   
   
或
   
   
   
   

    
    
    
    
make –jobs=4
   
   
   
   
 
make加上-s，表示silent，不输出详细log信息
之前折腾：
【记录】尝试用QEMU模拟ARM开发板去加载并运行Uboot，kernel，rootfs
参考的：
Virtual Development Board
中就用到：
   
   
   
   

    
    
    
    
sudo make install -s
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- versatile_defconfig -s
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- uImage -s
   
   
   
   
其中的-s参数，之前就猜测是silent的意思。
根本上面的–help输出的信息，果然是：
   
   
   
   

    
    
    
    

     
     
     
     

      
      
      
      
-s,
 –silent, –quiet Don’t echo recipes.
     
     
     
     
    
    
    
    
   
   
   
   
 
-f指定makefile文件
之前就知道的，可以通过-f指定特定的makefile文件的。
背景是：
当执行make时，默认会去（当前文件夹下）找名为Makefile的文件
如果此处你需要去运行特定文件名的makefile文件，比如my.mk
那么就可以通过-f去指定：
   
   
   
   

    
    
    
    
make –f my.mk
   
   
   
   
即可。
 make help可以用来查看当前支持哪些目标
一般来说，多数的makefile文件，除了最常见的make all，make clean等最常见的目标之外，往往都会有自己不同的目标供执行，即：
make xxx
make yyy
等等。
而想要去查看，有哪些xxx和yyy供你使用，可以通过make help去查看。
举例：
最近折腾的：
【记录】Ubuntu下为QEMU的arm平台交叉编译BusyBox
中的make help的输出，就是：
   
   
   
   

    
    
    
    
crifan@ubuntu:busybox-1.16.0$ make help
Cleaning:
  clean         - delete temporary files created by build
  distclean     - delete all non- source files (including .config)
  doc-clean     - delete all generated documentation

Build:
  all           - Executable and documentation
  busybox       - the swiss-army executable
  doc           - docs /BusyBox .{txt,html,1}
  html          - create html-based cross-reference

Configuration:
  allnoconfig       - disable all symbols in .config
  allyesconfig      - enable all symbols in .config (see defconfig)
  config        - text based configurator (of last resort)
  defconfig     - set .config to largest generic configuration
  menuconfig        - interactive curses-based configurator
  oldconfig     - resolve any unresolved symbols in .config
  hosttools         - build sed for the host.
              You can use these commands if the commands on the host
              is unusable. Afterwards use it like:
              make SED= "/home/crifan/develop/embedded/qemu/rootfs/busybox/busybox-1.16.0/sed"

Installation:
  install       - install busybox into CONFIG_PREFIX
  uninstall

Development:
  baseline      - create busybox_old for bloatcheck.
  bloatcheck        - show size difference between old and new versions
  check         - run the test suite for all applets
  checkhelp     - check for missing help-entries in Config. in
  randconfig        - generate a random configuration
  release       - create a distribution tarball
  sizes         - show size of all enabled busybox symbols
  objsizes      - show size of each .o object built
  bigdata       - show data objects, biggest first
  stksizes      - show stack users , biggest first
   
   
   
   
如此，就知道了：
当前的busybox的makefile中，支持如此多的目标，而想要查看当前busybox的各种stack信息，就可以去试试那个stksizes了：
   
   
   
   

    
    
    
    
crifan@ubuntu:busybox-1.16.0$ make ARCH=arm CROSS_COMPILE=arm-xscale-linux-gnueabi- stksizes
arm-xscale-linux-gnueabi-objdump -d busybox_unstripped | /home/crifan/develop/embedded/qemu/rootfs/busybox/busybox-1 .16.0 /scripts/checkstack .pl arm | uniq
buffered_vfprintf [busybox_unstripped]:         8384
phys_pages_info [busybox_unstripped]:           8192
__get_nprocs [busybox_unstripped]:          8192
__res_vinit [busybox_unstripped]:           8192
_IO_wfile_seekoff [busybox_unstripped]:         4224
__unix_grantpt [busybox_unstripped]:            4224
_IO_vfwprintf [busybox_unstripped]:         4224
grantpt [busybox_unstripped]:               4160
bb_full_fd_action [busybox_unstripped]:         4096
find_list_entry2 [busybox_unstripped]:          4096
readlink_main [busybox_unstripped]:         4096
pid_is_exec [busybox_unstripped]:           4096
execle [busybox_unstripped]:                4096
execl [busybox_unstripped]:             4096
execlp [busybox_unstripped]:                4096
_dl_get_origin [busybox_unstripped]:            4096
ipaddr_list_or_flush [busybox_unstripped]:      3664
iproute_list_or_flush [busybox_unstripped]:     3648
__c32 [busybox_unstripped]:             3600
buffered_vfprintf [busybox_unstripped]:         3302
__mpatan [busybox_unstripped]:              2976
fallbackSort [busybox_unstripped]:          2928
atan2Mp.constprop.0 [busybox_unstripped]:       2304
__mpsqrt [busybox_unstripped]:              2304
__slowpow [busybox_unstripped]:             2304
cal_main [busybox_unstripped]:              2288
internal_fnmatch [busybox_unstripped]:          2144
doCommands [busybox_unstripped]:            2112
__slowexp [busybox_unstripped]:             1984
__mpexp [busybox_unstripped]:               1984
normalized [busybox_unstripped]:            1968
get_next_block [busybox_unstripped]:            1968
identify_from_stdin [busybox_unstripped]:       1792
__ieee754_log [busybox_unstripped]:         1648
huft_build [busybox_unstripped]:            1488
iproute_modify [busybox_unstripped]:            1376
svc_getreq_common [busybox_unstripped]:         1328
__mpatan2 [busybox_unstripped]:             1312
inflate_block [busybox_unstripped]:         1296
_IO_vfprintf [busybox_unstripped]:          1296
__libc_message [busybox_unstripped]:            1280
getlogin_r [busybox_unstripped]:            1280
mainQSort3.constprop.2 [busybox_unstripped]:        1264
__gettextparse [busybox_unstripped]:            1248
iproute_get [busybox_unstripped]:           1184
rx_main [busybox_unstripped]:               1152
ether_wake_main [busybox_unstripped]:           1152
procps_scan [busybox_unstripped]:           1152
unwind_phase2_forced [busybox_unstripped]:      1152
build_trtable [busybox_unstripped]:         1126
wget_main [busybox_unstripped]:             1120
iprule_modify [busybox_unstripped]:         1120
getopt32 [busybox_unstripped]:              1104
_svcauth_des [busybox_unstripped]:          1088
two_way_long_needle [busybox_unstripped]:       1056
ether_hostton [busybox_unstripped]:         1056
check_existence_through_netlink [busybox_unstripped]:   1040
two_way_long_needle [busybox_unstripped]:       1040
clnt_sperror [busybox_unstripped]:          1040
clnt_spcreateerror [busybox_unstripped]:        1040
_dl_signal_error [busybox_unstripped]:          1040
internal_fnwmatch [busybox_unstripped]:         1030
bad_zone [busybox_unstripped]:              1024
get_dirsize [busybox_unstripped]:           1024
map_block2 [busybox_unstripped]:            1024
map_block [busybox_unstripped]:             1024
addLines [busybox_unstripped]:              1024
getNum [busybox_unstripped]:                1024
perror_internal [busybox_unstripped]:           1024
__getmntent_r [busybox_unstripped]:         1024
__mpsin [busybox_unstripped]:               996
__mpcos [busybox_unstripped]:               996
__mpsin1 [busybox_unstripped]:              992
__mpcos1 [busybox_unstripped]:              992
__sin32 [busybox_unstripped]:               988
__cos32 [busybox_unstripped]:               988
__mpranred [busybox_unstripped]:            988
__mplog [busybox_unstripped]:               984
udhcpc_main [busybox_unstripped]:           884
dhcprelay_main [busybox_unstripped]:            836
udhcpd_main [busybox_unstripped]:           824
sha512_process_block128 [busybox_unstripped]:       812
glob_in_dir [busybox_unstripped]:           804
init_exec [busybox_unstripped]:             788
write_wtmp [busybox_unstripped]:            780
nfsmount [busybox_unstripped]:              732
do_tunnels_list [busybox_unstripped]:           724
print_tunnel [busybox_unstripped]:          712
pututline_file [busybox_unstripped]:            708
if_readlist_proc [busybox_unstripped]:          696
udhcp_send_raw_packet [busybox_unstripped]:     692
arp_show [busybox_unstripped]:              684
__inv [busybox_unstripped]:             664
__gnu_Unwind_Backtrace [busybox_unstripped]:        664
udhcp_recv_raw_packet [busybox_unstripped]:     660
print_login_issue [busybox_unstripped]:         656
send_ACK [busybox_unstripped]:              644
send_release [busybox_unstripped]:          644
send_offer [busybox_unstripped]:            640
send_renew [busybox_unstripped]:            640
send_NAK [busybox_unstripped]:              636
send_discover [busybox_unstripped]:         636
send_inform [busybox_unstripped]:           632
send_decline [busybox_unstripped]:          632
send_select [busybox_unstripped]:           632
ash_main [busybox_unstripped]:              632
dnsd_main [busybox_unstripped]:             604
_dl_start_profile [busybox_unstripped]:         604
sha_crypt [busybox_unstripped]:             596
__gnu_Unwind_RaiseException [busybox_unstripped]:   580
_dl_map_object [busybox_unstripped]:            580
inetd_main [busybox_unstripped]:            576
readtoken1 [busybox_unstripped]:            572
_dl_debug_vdprintf [busybox_unstripped]:        556
process_dev [busybox_unstripped]:           544
get_header_tar [busybox_unstripped]:            540
uname_main [busybox_unstripped]:            540
last_main [busybox_unstripped]:             532
glob_in_dir [busybox_unstripped]:           532
dir_act [busybox_unstripped]:               524
retrieve_file_data [busybox_unstripped]:        524
log_option [busybox_unstripped]:            524
gaih_inet [busybox_unstripped]:             520
readprofile_main [busybox_unstripped]:          516
writeTarHeader [busybox_unstripped]:            516
_IO_vfscanf [busybox_unstripped]:           516
handle_net_output [busybox_unstripped]:         512
writeLongname [busybox_unstripped]:         512
getnameinfo [busybox_unstripped]:           484
print_addrinfo [busybox_unstripped]:            480
_nl_load_locale_from_archive [busybox_unstripped]:  460
read_alias_file [busybox_unstripped]:           460
_dl_discover_osversion [busybox_unstripped]:        460
authunix_create [busybox_unstripped]:           456
login_main [busybox_unstripped]:            452
print_route [busybox_unstripped]:           444
evalfun [busybox_unstripped]:               440
_dl_catch_error [busybox_unstripped]:           440
brctl_main [busybox_unstripped]:            420
evalbltin.isra.1 [busybox_unstripped]:          420
evaltree [busybox_unstripped]:              420
setvarsafe [busybox_unstripped]:            416
redirectsafe [busybox_unstripped]:          416
crond_main [busybox_unstripped]:            412
modprobe_main [busybox_unstripped]:         412
ipaddr_modify [busybox_unstripped]:         412
scan_proc_net [busybox_unstripped]:         412
_Unwind_VRS_Pop [busybox_unstripped]:           412
__sleep [busybox_unstripped]:               408
____strtod_l_internal [busybox_unstripped]:     404
exitshell [busybox_unstripped]:             404
bb_ask [busybox_unstripped]:                404
get_linux_version_code [busybox_unstripped]:        396
safe_gethostname [busybox_unstripped]:          396
safe_getdomainname [busybox_unstripped]:        396
getdomainname [busybox_unstripped]:         396
runsv_main [busybox_unstripped]:            392
__gethostname [busybox_unstripped]:         392
update_utmp [busybox_unstripped]:           384
print_rule [busybox_unstripped]:            384
parse_config_file [busybox_unstripped]:         380
reread_config_file [busybox_unstripped]:        380
set_loop [busybox_unstripped]:              380
fbset_main [busybox_unstripped]:            372
find_block_device [busybox_unstripped]:         372
arping_main [busybox_unstripped]:           364
_IO_vdprintf [busybox_unstripped]:          364
md5_crypt [busybox_unstripped]:             356
passwd_main [busybox_unstripped]:           348
__mbsrtowcs_l [busybox_unstripped]:         348
list_devs_in_proc_partititons [busybox_unstripped]: 344
sha1_process_block64 [busybox_unstripped]:      340
__glob64 [busybox_unstripped]:              340
display_process_list [busybox_unstripped]:      332
__wcsrtombs [busybox_unstripped]:           332
INET6_displayroutes [busybox_unstripped]:       328
__dvd [busybox_unstripped]:             328
mainSort [busybox_unstripped]:              324
__mbsnrtowcs [busybox_unstripped]:          324
__ttyname_r [busybox_unstripped]:           324
glob [busybox_unstripped]:              324
sulogin_main [busybox_unstripped]:          316
makedevs_main [busybox_unstripped]:         316
re_compile_fastmap_iter.isra.40 [busybox_unstripped]:   316
do_lzo_decompress [busybox_unstripped]:         312
do_system [busybox_unstripped]:             312
do_lzo_compress [busybox_unstripped]:           308
updwtmp_file [busybox_unstripped]:          308
getutline_r_file [busybox_unstripped]:          308
correct_password [busybox_unstripped]:          304
__libc_start_main [busybox_unstripped]:         304
telnetd_main [busybox_unstripped]:          300
read_line_input [busybox_unstripped]:           300
re_search_internal [busybox_unstripped]:        300
internal_getut_r [busybox_unstripped]:          300
crifan@ubuntu:busybox-1.16.0$
   
   
   
   
 

转自： http://www.crifan.com/summary_usage_about_make_linux_command/