u-boot，初试牛刀

手里拿到的uboot是uboot-2012，整个目录和之前的1.3.4没什么太大变化。但是系统启动初始化的流程，以及一些接口函数的定义变化了许多。以及初始化make的流程也变化，另外在nand的ecc校验算法增加了bch校验。

第一步，编译

linux下的编译，基本都是借用了Makefile和脚本以及链接文件协同合作，最后搞出来一个bin。

编译uboot也无外乎这样。只是稍微有些不同。

啥也不懂，啥也不知道怎么办？

那么make help 下吧，不识路，先问路。

#make help
Cleaning targets:
  clean		  - Remove most generated files but keep the config and
                    necessities for testing u-boot //除config配置文件，.o什么的统统删除
  clobber	  - Remove most generated files but keep the config//同上，差不多
  mrproper	  - Remove all generated files + config + various backup files//更进一步
  distclean	  - mrproper + remove editor backup and patch files//更进一步，包括补丁

Other generic targets:
  all		  - Build all necessary images depending on configuration//大白话，都统一来一遍
  u-boot	  - Build the bare u-boot//编译个裸u-boot
  dir/            - Build all files in dir and below//把dir目录下的文件统统来一遍
  dir/file.[oisS] - Build specified target only
  dir/file.lst    - Build specified mixed source/assembly target only
                    (requires a recent binutils and recent build (System.map))
  tags/TAGS	  - Generate tags file for editors
  cscope	  - Generate cscope index
  ubootrelease	  - Output the release version string
  ubootversion	  - Output the version stored in Makefile

Static analysers
  checkstack      - Generate a list of stack hogs //编译后，从裸uboot里，dump出一些栈大小信息

Documentation targets:
 U-Boot bootloader internal documentation in different formats:
  htmldocs        - HTML
  pdfdocs         - PDF
  psdocs          - Postscript
  xmldocs         - XML DocBook
  mandocs         - man pages
  installmandocs  - install man pages generated by mandocs
  cleandocs       - clean all generated DocBook files

  make V=0|1 [targets] 0 => quiet build (default), 1 => verbose build
  make V=2   [targets] 2 => give reason for rebuild of target
  make O=dir [targets] Locate all output files in "dir", including .config
  make C=1   [targets] Check all c source with $CHECK (sparse by default)
  make C=2   [targets] Force check of all c source with $CHECK
  make RECORDMCOUNT_WARN=1 [targets] Warn about ignored mcount sections
  make W=n   [targets] Enable extra gcc checks, n=1,2,3 where
		1: warnings which may be relevant and do not occur too often
		2: warnings which occur quite often but may still be relevant
		3: more obscure warnings, can most likely be ignored
		Multiple levels can be combined with W=12 or W=123

Execute "make" or "make all" to build all targets marked with [*]
For further info see the ./README file