U-Boot-1.1.6 is transplanted to the MINI2440 development board (1) - analysis before transplantation

Port U-Boot-1.1.6 to the MINI2440 development board and boot from NAND Flash (NOR Flash is not used).

What you need to prepare:

Linux environment: Ubuntu 16.04

Cross-compilation tool chain: arm-linux-gcc-3.4.5

U-Boot-1.1.6 Source: u-boot-1.1.6.tar.bz2

S3C2440手册：S3C2440A 32-BIT CMOS MICROCONTROLLER USERS MANUAL

ARM920T Technical Reference Manual: ARM920T Technical Reference Manual

Other related datasheets

Reference materials: "Complete Manual of Embedded Linux Application Development" and online blog (#^.^#).

Note: The following involves basic Linux operating commands and will not be described in detail.

Set up the cross-compilation environment:

It is recommended to use the compiled cross-compilation tool chain directly. The arm-linux-gcc-3.4.5 used here is to create a new folder in the directory:

soz@tzw-pc:~$ mkdir arm

soc@tzw-pc:~$ cd arm/

so-called@tzw-pc:~arm$ mkdir -p toolchains/arm-linux-gcc/3.4.5

Save the cross-compilation toolchain in a folder:

tzw@tzw-pc:~/arm$ ls toolchains/arm-linux-gcc/3.4.5/

arm-linux  bin  distributed  include  info  lib  libexec  man  tmp

The executable files in the /bin directory are the files used during compilation.

Then add the path of the cross-compilation tool chain to the environment variable. There are many ways to add it. Here, save it in the bash.bashrc file, open and edit bash.bashrc:

so-called@tzw-pc:~$ sudo gedit /etc/bash.bashrc

Start a new line at the end of the file and add the following statement. Be careful not to change other content in the file:

------- bash.bashrc -------

export PATH=$PATH:/home/tzw/arm/toolchains/arm-linux-gcc/3.4.5/bin

Save and close the file.

In Ubuntu, opening a new terminal or typing bash on the terminal to open a new shell will read /etc/bash.bashrc and ~/.bashrc. Therefore, using this method, you only need to reopen a terminal to make the environment variables take effect. . You can also enter the following command in the old terminal to make the environment variables take effect:

so-called@tzw-pc:~$ source /etc/bash.bashrc

Reopen a terminal (shortcut key: Ctrl+Alt+t) and enter the command:

so-called@tzw-pc:~$ arm-linux-gcc -v

Press Enter to see the output information:

Reading specs from /home/tzw/arm/toolchains/arm-linux-gcc/3.4.5/bin/../lib/gcc/arm-linux/3.4.5/specs

...

gcc version 3.4.5

Then the cross-compilation tool chain has been set up, and the last line is the version of GCC used. If the following message appears:

arm-linux-gcc: command not found

The instructions are not set correctly and you need to check whether the above steps are completed.

Get U-Boot source code:

Download the u-boot-1.1.6 source code compression package from the official website, create a new u-boot folder in the arm directory and extract the source code to the u-boot folder:

soc@tzw-pc:~/arm$ mkdir u-boot

soc@tzw-pc:~/arm$ cd u-boot

soz@tzw-pc:~/arm/u-boot$ tar -jxvf u-boot-1.1.6.tar.bz2

View the decompression results:

so-called@tzw-pc:~/arm/u-boot$ ls u-boot-1.1.6

arm_config.mk                  fs              MAKEALL

avr32_config.mk                i386_config.mk  Makefile

blackfin_config.mk             include         microblaze_config.mk

board                          lib_arm         mips_config.mk

CHANGELOG                      lib_avr32       mkconfig

CHANGELOG-before-U-Boot-1.1.5  lib_blackfin    nand_spl

common                         lib_generic     net

config.mk lib_i386 nios2_config.mk

COPYING                        lib_m68k        nios_config.mk

cpu                            lib_microblaze  post

CREDITS                        lib_mips        ppc_config.mk

disk                           lib_nios        README

doc                            lib_nios2       rtc

drivers                        lib_ppc         rules.mk

dtt                            m68k_config.mk  tools

examples                       MAINTAINERS

You can see the U-Boot source code in the /arm/u-boot/u-boot-1.1.6 directory.

Compile U-Boot-1.1.6 for the first time:

Instead of modifying the source code directly, copy the source code and modify it:

so-called@tzw-pc:~/arm/u-boot$ mkdir u-boot-mini2440-1.1.6

so-called@tzw-pc:~/arm/u-boot$ cp -r u-boot-1.1.6/* u-boot-mini2440-1.1.6/

View the copied results:

so-called@tzw-pc:~/arm/u-boot$ cd u-boot-mini2440-1.1.6/

soz@tzw-pc:~/arm/u-boot/u-boot-mini2440-1.1.6$ ls

arm_config.mk                  fs              MAKEALL

avr32_config.mk                i386_config.mk  Makefile

blackfin_config.mk             include         microblaze_config.mk

board                          lib_arm         mips_config.mk

CHANGELOG                      lib_avr32       mkconfig

CHANGELOG-before-U-Boot-1.1.5  lib_blackfin    nand_spl

common                         lib_generic     net

config.mk lib_i386 nios2_config.mk

COPYING                        lib_m68k        nios_config.mk

cpu                            lib_microblaze  post

CREDITS                        lib_mips        ppc_config.mk

disk                           lib_nios        README

doc                            lib_nios2       rtc

drivers                        lib_ppc         rules.mk

dtt                            m68k_config.mk  tools

examples                       MAINTAINERS

mini2440开发板使用Samsung的S3C2440芯片，与U-Boot-1.1.6中已有的smdk2410开发板（采用Samsung S3C2410芯片）相似，因此在smdk2410的基础上进行移植。

首先测试一下源码是否能正常编译：

tzw@tzw-pc:~/arm/u-boot/u-boot-mini2440-1.1.6$ make distclean

tzw@tzw-pc:~/arm/u-boot/u-boot-mini2440-1.1.6$ make smdk2410_config

tzw@tzw-pc:~/arm/u-boot/u-boot-mini2440-1.1.6$ make

make distclean：完全清除所有配置以及生成的文件。

make clean：清除所有生成的文件，会保留配置。

make smdk2410_config：进行smdk2410开发板的配置。

make：根据Makefile生成二进制文件u-boot.bin。

等待一段时间，可以在/u-boot-mini2440-1.1.6目录下看到生成的二进制文件：

tzw@tzw-pc:~/arm/u-boot/u-boot-mini2440-1.1.6$ ls u-boot.bin

u-boot.bin

如果开发板是smdk2410的话，那么将这个二进制文件烧写进开发板，就可以在串口上看到U-Boot的运行输出信息了。

如果make执行过程中出现错误的话，一般是一些依赖的库没有安装，根据报错信息依次安装所需要的库进行了，直到最后生成u-boot.bin这个二进制文件。

移植前的分析：

由上述可知，U-Boot的编译首先需要配置，然后才进行编译：

tzw@tzw-pc:~/arm/u-boot/u-boot-mini2440-1.1.6$ make smdk2410_config --just-print

make smdk2410_config --just-print：仅输出将要执行的语句，但并不执行。

输出信息：

tzw@tzw-pc:~/arm/u-boot/u-boot-mini2440-1.1.6$ make smdk2410_config --just-print

rm -f include/config.h include/config.mk

    board/*/config.tmp board/*/*/config.tmp

/home/tzw/arm/u-boot/u-boot-mini2440-1.1.6/mkconfig smdk2410 arm arm920t smdk2410 NULL s3c24x0

可知首先删除了原先的一些配置相关的文件：

include/config.h

include/config.mk

board/*/config.tmp

board/*/*/config.tmp

即/include目录下的config.h、config.mk，/board目录下所有与配置相关的config.tmp文件。

然后执行：

mkconfig smdk2410 arm arm920t smdk2410 NULL s3c24x0

mkconfig是/u-boot-mini2440-1.1.6目录下的一个文件，后面是输入的6个参数：

mkconfig smdk2410 arm arm920t smdk2410 NULL s3c24x0

$0       $1       $2  $3      $4       $5   $6

$0表示所执行的程序的名称；

$1~$6为所执行的程序的输入参数。

从Makefile中可知：

------- Makefile -------

92 MKCONFIG    := $(SRCTREE)/mkconfig

93 export MKCONFIG

...

1879 smdk2410_config    :    unconfig

1880     @$(MKCONFIG) $(@:_config=) arm arm920t smdk2410 NULL s3c24x0

打开顶层mkconfig文件，进行分析：

默认创建新的配置文件，并将板子的名称置为""：

------- mkconfig -------

11 APPEND=no    # Default: Create new config file

12 BOARD_NAME=""    # Name to print in make output

判断传入的参数是否含有特殊项，并进行处理，这里并无特殊项：

------- mkconfig -------

14 while [ $# -gt 0 ] ; do

15     case "$1" in

16     --) shift ; break ;;

17     -a) shift ; APPEND=yes ;;

18     -n) shift ; BOARD_NAME="${1%%_config}" ; shift ;;

19     *)  break ;;

20     esac

21 done

$# 所执行的程序的参数的个数；

-gt 大于（greater than）；

-eq 等于（equal）；

-ne 不等于（not equal）；

-ge 大于等于（greater and equal）；

-lt 小于（less than）；

-le小于等于（less and equal）。

第23行判断开发板名称是否存在，并将其赋值为第一个参数，即BOARD_NAME=smdk2410：

------- mkconfig -------

23 [ "${BOARD_NAME}" ] || BOARD_NAME="$1"

第25、26行对参数个数进行判断，不满足要求则退出：

------- mkconfig -------

25 [ $# -lt 4 ] && exit 1

26 [ $# -gt 6 ] && exit 1

输出配置信息：Configuring for smdk2410 board...

------- mkconfig -------

28 echo "Configuring for ${BOARD_NAME} board..."

第33行到62行新建链接文件：

------- mkconfig -------

33 if [ "$SRCTREE" != "$OBJTREE" ] ; then

34     mkdir -p ${OBJTREE}/include

35     mkdir -p ${OBJTREE}/include2

36     cd ${OBJTREE}/include2

37     rm -f asm

38     ln -s ${SRCTREE}/include/asm-$2 asm

39     LNPREFIX="../../include2/asm/"

40     cd ../include

41     rm -rf asm-$2

42     rm -f asm

43     mkdir asm-$2

44     ln -s asm-$2 asm

45 else

46     cd ./include

47     rm -f asm

48     ln -s asm-$2 asm

49 fi

50 

51 rm -f asm-$2/arch

52 

53 if [ -z "$6" -o "$6" = "NULL" ] ; then

54     ln -s ${LNPREFIX}arch-$3 asm-$2/arch

55 else

56     ln -s ${LNPREFIX}arch-$6 asm-$2/arch

57 be

58 

59 if [ "$2" = "arm" ] ; then

60     rm -f asm-$2/proc

61     ln -s ${LNPREFIX}proc-armv asm-$2/proc

62 fi

The first if judgment executes the else branch on line 45, enters the /include directory, and creates a link file /asm pointing to /asm-arm.

Then delete the original /asm-arm/arch directory.

The second if judgment executes the else branch on line 55 and creates a link file /asm-arm/arch pointing to /arch-s3c24x0.

Finally, execute the judgment on line 60, delete the original /asm-arm/proc directory, and create a link file /asm-arm/proc pointing to /asm-arm/proc-armv.

Lines 67 to 73 create the config.mk file:

------- mkconfig -------

67 echo "ARCH   = $2" >  config.mk

68 echo "CPU    = $3" >> config.mk

69 echo "BOARD  = $4" >> config.mk

70 

71 [ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk

72 

73 [ "$6" ] && [ "$6" != "NULL" ] && echo "SOC    = $6" >> config.mk

Contents of the /include/config.mk file:

------- /include/config.mk -------

1 ARCH   = arm

2 CPU    = arm920t

3 BOARD = smdk2410

4 SOC    = s3c24x0

Finally create the config.h file:

------- mkconfig -------

78 if [ "$APPEND" = "yes" ]    # Append to existing config file

79 then

80     echo >> config.h

81 else

82     > config.h        # Create new config file

83 be

84 echo "/* Automatically generated - do not edit */" >>config.h

85 echo "#include " >>config.h

Contents of the /include/config.h file:

------- /include/config.h -------

1 /* Automatically generated - do not edit */

2 #include

Therefore, the result of the make smdk2410_config command is to call the mkconfig command for configuration, delete the original link file, create a new link file, and generate two files, config.mk and config.h.