UBOOT项目中对Makefile的解析

 VERSION = 1

    
 PATCHLEVEL = 3
    
 SUBLEVEL = 4
    
 EXTRAVERSION =
    
 U_BOOT_VERSION = $(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)
    
 VERSION_FILE = $(obj)include/version_autogenerated.h
    
  
    
 HOSTARCH := $(shell uname -m | \
    
 	sed -e s/i.86/i386/ \
    
 	    -e s/sun4u/sparc64/ \
    
 	    -e s/arm.*/arm/ \
    
 	    -e s/sa110/arm/ \
    
 	    -e s/powerpc/ppc/ \
    
 	    -e s/ppc64/ppc/ \
    
 	    -e s/macppc/ppc/)
    
  
    
 HOSTOS := $(shell uname -s | tr '[:upper:]' '[:lower:]' | \
    
 	    sed -e 's/\(cygwin\).*/cyg