Configuration analysis of U-boot (2)

Brief analysis of Makefile
The compilation connections for all these directories are determined by the makefile of the top-level directory.

1. in the makefile, there are:

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

% is a wildcard, make Xxx_config is the target. The target's dependence is unconfig,

unconfig 's command is to delete some files, which are generated from the make xxx_config process. Unconfig is the cleanup configuration.

Mkconfig: = $ (Srctree)/mkconfig

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

equivalent to ./mkconfig 100ask24x0 arm arm920t 100ask24x0 NULL s3c24x0

[email protected] means target.

$ (@:_config=) is a substitution reference for a variable

The format is "$ (var:a=b)" (or "${var:a=b}"), meaning: Replace the word "B" at the end of all "A" characters in the variable "VAR".

2. The following is the execution of the Mkconfig script

Mkconfig file:

./mkconfig 100ask24x0 arm arm920t 100ask24x0 NULL s3c24x0

$ $4 $ $6

Objtree: = $ (if $ (build_dir), $ (Build_dir), $ (CURDIR))
Srctree: = $ (CURDIR)
CurDir is a special parameter in Makefile that represents the current directory. So, the meaning of this sentence is to decide whether to use Build_dir or CurDir.

["${board_name}"] | | Board_name= "$" #BOARD_NAME =100ask24x0 　　　　
$n under Linux script for incoming parameter nth

[$#-lt 4] && exit 1
[$#-GT 6] && exit 1 #目标参数小于4大于6退出

The number of $# parameters -lt less than-gt greater than

echo "Configuring for ${board_name} BOARD ..."
echo Print

Objtree: = $ (if $ (build_dir), $ (Build_dir), $ (CURDIR))
If the definition build_dir equals Build_dir no person is CurDir

CD./include
Rm-f ASM
Ln-s asm-$2 ASM #ln-S asm-arm ASM

Delete the original ASM build a link file asm point to Asm-arm

Rm-f asm-$2/arch # rm-f Asm-arm/arch

If [-Z ' $6 "-o" $6 "=" NULL "];

if $6 is empty or equals null
Ln-s ${lnprefix}arch-$6 asm-$2/arch # ln-s arch-s3c24x0 asm-100ask24x0/arch

Delete original arch build a link file arch pointing arch-s3c24x0

rm-f asm-$2/proc # rm-f Asm-arm/proc
ln-s ${lnprefix}proc-armv asm-$2/proc # ln-s PROC-ARMV asm-arm/proc

Delete original proc Create a link file proc point to PROC-ARMV

#

# Create include file for Make

#

echo "ARCH = $" > config.mk

echo "CPU = $ $" >> config.mk

echo "BOARD = $4" >> config.mk

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

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

Create a file containing the top level makefile INCLUDE/CONFIG.MK

#
# 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

Create a Development Board-related header file Include/config.h

Content is/* automatically generated-do not edit */

#include <configs/100ask24x0.h>

Now summarize and review the configuration command make smdk2410_config; actual execution "./mkconfig 100ask24x0 arm arm920t 100ask24x0 NULL s3c24x0" command

Assume execution "./mkconfig $ $4 $ $6" command. The following results are generated.

(1) Development Board name Board_name equals $ $.

(2) Create a link to the platform, Development Board related files, as shown below;

Ln-s asm-$2 ASM

Ln-s ${lnprefix}arch-$6 Asm-$2/arch

Ln-s ${LNPREFIX}PROC-ARMV Asm-$2/proc

(3) Create the top-level makefile containing the file include/config.mk as follows:

ARCH = Arm

CPU =arm920t

BOARD = 100ask24x0

SOC = s3c24x0

(4) Create the Development Board related header file Include/config.h as follows:

/* Automatically generated-do not edit */

#include <configs/100ask24x0.h>

The top level makefile calls the makefile of each subdirectory to generate the target file or the target file repository.
Then connect all target files (libraries) to generate the final u-boot.bin.
The main goals of the connection (library) are as follows:
OBJS = cpu/$ (CPU)/START.O
LIBS = LIB_GENERIC/LIBGENERIC.A
LIBS + = board/$ (boarddir)/lib$ (board). A
LIBS + = cpu/$ (CPU)/lib$ (CPU). A
Ifdef SOC
LIBS + = cpu/$ (CPU)/$ (SOC)/lib$ (SOC). A
endif
LIBS + = lib_$ (arch)/lib$ (arch). A
LIBS + = FS/CRAMFS/LIBCRAMFS.A fs/fat/libfat.a fs/fdos/libfdos.a fs/jffs2/libjffs2.a/
FS/REISERFS/LIBREISERFS.A FS/EXT2/LIBEXT2FS.A
LIBS + = Net/libnet.a
LIBS + = disk/libdisk.a
LIBS + = RTC/LIBRTC.A
LIBS + = Dtt/libdtt.a
LIBS + = DRIVERS/LIBDRIVERS.A
LIBS + = Drivers/nand/libnand.a
LIBS + = Drivers/nand_legacy/libnand_legacy.a
LIBS + = Drivers/sk98lin/libsk98lin.a
LIBS + = Post/libpost.a post/cpu/libcpu.a
LIBS + = Common/libcommon.a
LIBS + = $ (boardlibs)
The main factors that are obviously related to the platform are:
cpu/$ (CPU)/START.O
board/$ (Boarddir)/lib$ (board). A
cpu/$ (CPU)/lib$ (CPU). A
cpu/$ (CPU)/$ (Soc)/lib$ (SOC). A
lib_$ (Arch)/lib$ (arch). A
The four variables in this are defined in INCLUDE/CONFIG.MK (see above).
The rest are platform independent.
So when considering porting, the main consideration is the corresponding directory of these target files (libraries).

Configuration analysis of U-boot (2)