Make config analysis of configuration commands before uboot compilation

Compiling uboot It should be implemented before make config, Here is provided by Baiwen uboot For example （ I have been learning with teacher Wei Dongshan's materials , Really good ）, Compare the video of Mr. Wei Dongshan , Yes make config Talk about your understanding in the process .
First download u-boot-1.6.tar.bz2 as well as u-boot-1.6.patch
step ：
1. decompression tar xjf u-boot-1.6.tar.bz2
2. Enter the source directory cd u-boot-1.6
3. patch up patch -p1 <…/u-boot-1.6.patch
4. To configure make 100ask24x0_config
Let's analyze make 100ask24x0_config

One 、make 100ask24x0_config analysis

stay Makefile You can find
original text ：

100ask24x0_config	:	unconfig
	@$(MKCONFIG) $(@:_config=) arm arm920t 100ask24x0 NULL s3c24x0

MKCONFIG := $(SRCTREE)/mkconfig
SRCTREE := $(CURDIR)
After variable expansion ·：

100ask24x0_config	:	unconfig
	$(CURDIR)/mkconfig 100ask24x0 arm arm920t 100ask24x0 NULL s3c24x0

In the current path mkconfig Script run , Parameter is 100ask24x0 arm arm920t 100ask24x0 NULL s3c24x0
$0 $1 $2 ……$n Represents the parameters of the command line ,$0 It's the command itself ,$1 Is the first parameter ,$n It's No n Parameters
$# Indicates the number of parameters
Before this command is run , Execute before running unconfig：

unconfig:
	@rm -f $(obj)include/config.h $(obj)include/config.mk \
		$(obj)board/*/config.tmp $(obj)board/*/*/config.tmp

obj := $(OBJTREE)/
OBJTREE := $(if $(BUILD_DIR),$(BUILD_DIR),$(CURDIR))
If you define BUILD_DIR Just use , If there is no definition, use CURDIR.
I.e. clearing $(CURDIR)/include/config.h $(CURDIR)/include/config.mk Etc

Two 、mkconfig Script analysis

#!/bin/sh -e

# Script to create header files and links to configure
# U-Boot for a specific board.
#
# Parameters: Target Architecture CPU Board [VENDOR] [SOC]
#
# (C) 2002-2006 DENX Software Engineering, Wolfgang Denk <[email protected]>
#
\
APPEND=no	# Default: Create new config file
BOARD_NAME=""	# Name to print in make output

while [ $# -gt 0 ] ; do
	case "$1" in
	--) shift ; break ;;
	-a) shift ; APPEND=yes ;;
	-n) shift ; BOARD_NAME="${1%%_config}" ; shift ;;
	*)  break ;;
	esac
done

[ "${BOARD_NAME}" ] || BOARD_NAME="$1"
******************************************************************************
 Undefined BOARD_NAME Is defined as $1, namely 100ask24x0
******************************************************************************
[ $# -lt 4 ] && exit 1
[ $# -gt 6 ] && exit 1
******************************************************************************
$# Indicates the number of parameters , by 6, The number of parameters is less than 4 Or greater than 6 All quit 
******************************************************************************
echo "Configuring for ${BOARD_NAME} board..."

#
# Create link to architecture specific headers
#
if [ "$SRCTREE" != "$OBJTREE" ] ; then
	mkdir -p ${OBJTREE}/include
	mkdir -p ${OBJTREE}/include2
	cd ${OBJTREE}/include2
	rm -f asm
	ln -s ${SRCTREE}/include/asm-$2 asm
	LNPREFIX="../../include2/asm/"
	cd ../include
	rm -rf asm-$2
	rm -f asm
	mkdir asm-$2
	ln -s asm-$2 asm
else
	cd ./include
	rm -f asm
	ln -s asm-$2 asm
******************************************************************************
 command ：ln -s asm-arm asm
 use ： Create a point to asm-arm Link file for asm;
 reason ：#include<asm-type.h>, compile arm when #include<asm-arm.h>, compile i386 when #include<asm-i386.h>,
 After using this command, it is written directly as #include<asm.h> No need to change type.
******************************************************************************
fi

rm -f asm-$2/arch

if [ -z "$6" -o "$6" = "NULL" ] ; then
	ln -s ${LNPREFIX}arch-$3 asm-$2/arch
else
	ln -s ${LNPREFIX}arch-$6 asm-$2/arch
fi
******************************************************************************
 take asm-arm/arch Point to arch-s3c24x0
******************************************************************************
if [ "$2" = "arm" ] ; then
	rm -f asm-$2/proc
	ln -s ${LNPREFIX}proc-armv asm-$2/proc
fi
******************************************************************************
 take asm-arm/proc Point to proc-armv
******************************************************************************

#
# Create include file for Make
#
echo "ARCH = $2" >  config.mk
echo "CPU = $3" >> config.mk
echo "BOARD = $4" >> config.mk

[ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk

[ "$6" ] && [ "$6" != "NULL" ] && echo "SOC = $6" >> config.mk
******************************************************************************
 establish config.mk, The content is 
ARCH   = arm
CPU    = arm920t
BOARD  = 100ask24x0
SOC    = s3c24x0
******************************************************************************
#
# Create board specific header file
#
if [ "$APPEND" = "yes" ]	# Append to existing config file
then
	echo >> config.h
else
	> config.h		# Create new config file
fi
echo "/* Automatically generated - do not edit */" >>config.h
echo "#include <configs/$1.h>" >>config.h

******************************************************************************
 establish config.h, The content is 
/* Automatically generated - do not edit */
#include <configs/100ask24x0.h>
******************************************************************************
exit 0