在lib/main.sh当中
13 if [[ $(basename $0) == main.sh ]]; then
14 echo "Please use compile.sh to start the build process"
15 exit -1
16 fi
17
18 # default umask for root is 022 so parent directories won't be group writeable without this
19 # this is used instead of making the chmod in prepare_host() recursive
20 umask 002
21
22 # destination
23 DEST=$SRC/output
24
25 TTY_X=$(($(stty size | awk '{print $2}')-6)) # determine terminal width
26 TTY_Y=$(($(stty size | awk '{print $1}')-6)) # determine terminal height
2713-16行，由于 main.sh脚本的执行需要在compile.sh内 被调用，不可以直接通过lib/main.sh，在上一节当中我们总结了compile.sh的功能。
23行,设置最终镜像默认的输出目录
25-25行，主要是后面会使用dialog命令做人机交互时，用来设置对话框的大小。TTY_X TTY_Y会根据终端的变化而变化。
在lib/main.sh当中
28 # We'll use this title on all menus
29 backtitle="Armbian building script, http://www.armbian.com | Author: Igor Pecovnik"
30
31 # if language not set, set to english
32 [[ -z $LANGUAGE ]] && export LANGUAGE="en_US:en"
33
34 # default console if not set
35 [[ -z $CONSOLE_CHAR ]] && export CONSOLE_CHAR="UTF-8"
36
37 [[ -z $FORCE_CHECKOUT ]] && FORCE_CHECKOUT=yes
3829行，用来设置对话框的标题
32行，用来设置LANGUAGE
35行，用来设置终端的输出字符集
37行，用来设置变量FORCE_CHECKOUT,后面拉取代码时会用到，在lib/generate.sh脚本，在fetch_from_repo() 钩子函数当中会用到，如下所示：
261 # working directory is not clean
262 if [[ $FORCE_CHECKOUT == yes ]]; then
263 display_alert "Checking out"
264 git checkout -f -q HEAD继续回到lib/mian.sh当中，如下所示：加载相关的脚本函数，在后面的编译过程当中会用到，里面的内容比较多，我们在调用到的时候再进行详细分析
39 # Load libraries
40 source $SRC/lib/debootstrap-ng.sh # System specific install
41 source $SRC/lib/image-helpers.sh # helpers for OS image building
42 source $SRC/lib/distributions.sh # System specific install
43 source $SRC/lib/desktop.sh # Desktop specific install
44 source $SRC/lib/compilation.sh # Patching and compilation of kernel, uboot, ATF
45 source $SRC/lib/makeboarddeb.sh # Create board support package
46 source $SRC/lib/general.sh # General functions
47 source $SRC/lib/chroot-buildpackages.sh # Building packages in chroot
继续阅读lib/main.sh
49 # compress and remove old logs
50 mkdir -p $DEST/debug
51 (cd $DEST/debug && tar -czf logs-$(<timestamp).tgz *.log) > /dev/null 2>&1
52 rm -f $DEST/debug/*.log > /dev/null 2>&1
53 date +"%d_%m_%Y-%H_%M_%S" > $DEST/debug/timestamp
54 # delete compressed logs older than 7 days
55 (cd $DEST/debug && find . -name '*.tgz' -mtime +7 -delete) > /dev/null
56
57 if [[ $PROGRESS_DISPLAY == none ]]; then
58 OUTPUT_VERYSILENT=yes
59 elif [[ $PROGRESS_DISPLAY == dialog ]]; then
60 OUTPUT_DIALOG=yes
61 fi
62 if [[ $PROGRESS_LOG_TO_FILE != yes ]]; then unset PROGRESS_LOG_TO_FILE; fi
63
64 SHOW_WARNING=yes
65
66 if [[ $USE_CCACHE != no ]]; then
67 CCACHE=ccache
68 export PATH="/usr/lib/ccache:$PATH"
69 # private ccache directory to avoid permission issues when using build script with "sudo"
70 # see https://ccache.samba.org/manual.html#_sharing_a_cache for alternative solution
71 [[ $PRIVATE_CCACHE == yes ]] && export CCACHE_DIR=$SRC/cache/ccache
72 else
73 CCACHE=""
74 fi49-56行，主要是对之前的log文件进行压缩，并删除超过7天的log.
57-62行，由于之前的PROGRESS_DISPLAY PROGRESS_LOG_TO_FILE 都没有设置，流程不会被执行。
64行， 设置SHOW_WARNING=yes
66-71行，由于在config-default.conf当中， USE_CCACHE没有被默认设置，67 68 这两行会被执行
在lib/main.sh当中会调用到prepare_host,
76 # Check and install dependencies, directory structure and settings
77 prepare_host该脚本函数在lib/general.sh， 第501行当中有定义，我们来看一下实现
495 # prepare_host
496 #
497 # * checks and installs necessary packages
498 # * creates directory structure
499 # * changes system settings
500 #
501 prepare_host()
502 {
503 display_alert "Preparing" "host" "info"
504
505 if [[ $(dpkg --print-architecture) != amd64 ]]; then
506 display_alert "Please read documentation to set up proper compilation environment"
507 display_alert "http://www.armbian.com/using-armbian-tools/"
508 exit_with_error "Running this tool on non x86-x64 build host in not supported"
509 fi
510
511 # exit if package manager is running in the back
512 while true; do
513 fuser -s /var/lib/dpkg/lock
514 if [[ $? = 0 ]]; then
515 display_alert "Package manager is running in the background." "retrying in 30 sec" "wrn"
516 sleep 30
517 else
518 break
519 fi
520 done
521
522 # need lsb_release to decide what to install
523 if [[ $(dpkg-query -W -f='${db:Status-Abbrev}\n' lsb-release 2>/dev/null) != *ii* ]]; then
524 display_alert "Installing package" "lsb-release"
525 apt -q update && apt install -q -y --no-install-recommends lsb-release
526 fi
527
528 # packages list for host
529 # NOTE: please sync any changes here with the Dockerfile and Vagrantfile
530 local hostdeps="wget ca-certificates device-tree-compiler pv bc lzop zip binfmt-support build-essential ccache debootstrap ntpdate \
531 gawk gcc-arm-linux-gnueabihf qemu-user-static u-boot-tools uuid-dev zlib1g-dev unzip libusb-1.0-0-dev fakeroot \
532 parted pkg-config libncurses5-dev whiptail debian-keyring debian-archive-keyring f2fs-tools libfile-fcntllock-perl rsync libssl-dev \
533 nfs-kernel-server btrfs-tools ncurses-term p7zip-full kmod dosfstools libc6-dev-armhf-cross \
534 curl patchutils python liblz4-tool libpython2.7-dev linux-base swig libpython-dev aptly acl \
535 locales ncurses-base pixz dialog systemd-container udev lib32stdc++6 libc6-i386 lib32ncurses5 lib32tinfo5 \
536 bison libbison-dev flex libfl-dev"
537
538 local codename=$(lsb_release -sc)
539 display_alert "Build host OS release" "${codename:-(unknown)}" "info"
540
541 # Ubuntu Xenial x86_64 is the only fully supported host OS release
542 # Ubuntu Bionic x86_64 support is WIP, especially for building full images and additional packages
543 # Using Docker/VirtualBox/Vagrant is the only supported way to run the build script on other Linux distributions
544 #
545 # NO_HOST_RELEASE_CHECK overrides the check for a supported host system
546 # Disable host OS check at your own risk, any issues reported with unsupported releases will be closed without a discussion
547 if [[ -z $codename || "xenial bionic" != *"$codename"* ]]; then
548 if [[ $NO_HOST_RELEASE_CHECK == yes ]]; then
549 display_alert "You are running on an unsupported system" "${codename:-(unknown)}" "wrn"
550 display_alert "Do not report any errors, warnings or other issues encountered beyond this point" "" "wrn"
551 else
552 exit_with_error "It seems you ignore documentation and run an unsupported build system: ${codename:-(unknown)}"
553 fi
554 fi
555
556 if grep -qE "(Microsoft|WSL)" /proc/version; then
557 exit_with_error "Windows subsystem for Linux is not a supported build environment"
558 fi
559
560 grep -q i386 <(dpkg --print-foreign-architectures) || dpkg --add-architecture i386
561 if systemd-detect-virt -q -c; then
562 display_alert "Running in container" "$(systemd-detect-virt)" "info"
563 # disable apt-cacher unless NO_APT_CACHER=no is not specified explicitly
564 if [[ $NO_APT_CACHER != no ]]; then
565 display_alert "apt-cacher is disabled in containers, set NO_APT_CACHER=no to override" "" "wrn"
566 NO_APT_CACHER=yes
567 fi
568 CONTAINER_COMPAT=yes
569 # trying to use nested containers is not a good idea, so don't permit EXTERNAL_NEW=compile
570 if [[ $EXTERNAL_NEW == compile ]]; then
571 display_alert "EXTERNAL_NEW=compile is not available when running in container, setting to prebuilt" "" "wrn"
572 EXTERNAL_NEW=prebuilt
573 fi
574 SYNC_CLOCK=no
575 fi
576
577 # warning: apt-cacher-ng will fail if installed and used both on host and in container/chroot environment with shared network
578 # set NO_APT_CACHER=yes to prevent installation errors in such case
579 if [[ $NO_APT_CACHER != yes ]]; then hostdeps="$hostdeps apt-cacher-ng"; fi
580
581 local deps=()
582 local installed=$(dpkg-query -W -f '${db:Status-Abbrev}|${binary:Package}\n' '*' 2>/dev/null | grep '^ii' | awk -F '|' '{print $2}' | cut -d ':' -f 1)
583
584 for packet in $hostdeps; do
585 if ! grep -q -x -e "$packet" <<< "$installed"; then deps+=("$packet"); fi
586 done
587
588 # distribution packages are buggy, download from author
589 if [[ ! -f /etc/apt/sources.list.d/aptly.list ]]; then
590 display_alert "Updating from external repository" "aptly" "info"
591 apt-key adv --keyserver pool.sks-keyservers.net --recv-keys ED75B5A4483DA07C >/dev/null 2>&1
592 echo "deb http://repo.aptly.info/ squeeze main" > /etc/apt/sources.list.d/aptly.list
593 fi
594
595 if [[ ${#deps[@]} -gt 0 ]]; then
596 display_alert "Installing build dependencies"
597 apt -q update
598 apt -y upgrade
599 apt -q -y --no-install-recommends install "${deps[@]}" | tee -a $DEST/debug/hostdeps.log
600 update-ccache-symlinks
601 fi
602
603 # Temorally broken in Bionic, reverting to prvious version
604 # https://github.com/aptly-dev/aptly/issues/740
605 if [[ $(dpkg -s aptly | grep '^Version:' | sed 's/Version: //') != "1.2.0" && "$codename" == "bionic" ]]; then
606 apt -qq -y --allow-downgrades install aptly=1.2.0
607 fi
608
609 # sync clock
610 if [[ $SYNC_CLOCK != no ]]; then
611 display_alert "Syncing clock" "host" "info"
612 ntpdate -s ${NTP_SERVER:- time.ijs.si}
613 fi
614
615 if [[ $(dpkg-query -W -f='${db:Status-Abbrev}\n' 'zlib1g:i386' 2>/dev/null) != *ii* ]]; then
616 apt install -qq -y --no-install-recommends zlib1g:i386 >/dev/null 2>&1
617 fi
618
619 # enable arm binary format so that the cross-architecture chroot environment will work
620 if [[ $KERNEL_ONLY != yes ]]; then
621 modprobe -q binfmt_misc
622 mountpoint -q /proc/sys/fs/binfmt_misc/ || mount binfmt_misc -t binfmt_misc /proc/sys/fs/binfmt_misc
623 test -e /proc/sys/fs/binfmt_misc/qemu-arm || update-binfmts --enable qemu-arm
624 test -e /proc/sys/fs/binfmt_misc/qemu-aarch64 || update-binfmts --enable qemu-aarch64
625 fi
626
627 # create directory structure
628 mkdir -p $SRC/{cache,output,userpatches}
629 if [[ -n $SUDO_USER ]]; then
630 chgrp --quiet sudo cache output userpatches
631 # SGID bit on cache/sources breaks kernel dpkg packaging
632 chmod --quiet g+w,g+s output userpatches
633 # fix existing permissions
634 find $SRC/output $SRC/userpatches -type d ! -group sudo -exec chgrp --quiet sudo {} \;
635 find $SRC/output $SRC/userpatches -type d ! -perm -g+w,g+s -exec chmod --quiet g+w,g+s {} \;
636 fi
637 mkdir -p $DEST/debs/extra $DEST/{config,debug,patch} $SRC/userpatches/overlay $SRC/cache/{sources,toolchains,utility,rootfs} $SRC/.tmp
638
639 find $SRC/patch -type d ! -name . | sed "s%/patch%/userpatches%" | xargs mkdir -p
640
641 # download external Linaro compiler and missing special dependencies since they are needed for certain sources
642
643 # Use backup server by default to balance the load
644
645 ARMBIANSERVER=dl.armbian.com
646
647 local toolchains=(
648 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-arm-linux-gnueabihf-4.8-2014.04_linux.tar.xz"
649 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-4.9.4-2017.01-x86_64_aarch64-linux-gnu.tar.xz"
650 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-4.9.4-2017.01-x86_64_arm-linux-gnueabi.tar.xz"
651 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-4.9.4-2017.01-x86_64_arm-linux-gnueabihf.tar.xz"
652 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-5.5.0-2017.10-x86_64_aarch64-linux-gnu.tar.xz"
653 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-5.5.0-2017.10-x86_64_arm-linux-gnueabi.tar.xz"
654 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-5.5.0-2017.10-x86_64_arm-linux-gnueabihf.tar.xz"
655 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-6.4.1-2017.11-x86_64_arm-linux-gnueabihf.tar.xz"
656 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-6.4.1-2017.11-x86_64_aarch64-linux-gnu.tar.xz"
657 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-7.2.1-2017.11-x86_64_aarch64-linux-gnu.tar.xz"
658 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-7.2.1-2017.11-x86_64_arm-linux-gnueabihf.tar.xz"
659 "https://${ARMBIANSERVER}/_toolchains/gcc-linaro-7.2.1-2017.11-x86_64_arm-eabi.tar.xz"
660 )
661
662 for toolchain in ${toolchains[@]}; do
663 download_toolchain "$toolchain"
664 done
665
666 rm -rf $SRC/cache/toolchains/*.tar.xz $SRC/cache/toolchains/*.tar.xz.asc
667 local existing_dirs=( $(ls -1 $SRC/cache/toolchains) )
668 for dir in ${existing_dirs[@]}; do
669 local found=no
670 for toolchain in ${toolchains[@]}; do
671 local filename=${toolchain##*/}
672 local dirname=${filename//.tar.xz}
673 [[ $dir == $dirname ]] && found=yes
674 done
675 if [[ $found == no ]]; then
676 display_alert "Removing obsolete toolchain" "$dir"
677 rm -rf $SRC/cache/toolchains/$dir
678 fi
679 done
680
681 # download etcher CLI utility
682 download_etcher_cli
683
684 [[ ! -f $SRC/userpatches/customize-image.sh ]] && cp $SRC/config/templates/customize-image.sh.template $SRC/userpatches/customize-image.sh
685
686 if [[ ! -f $SRC/userpatches/README ]]; then
687 rm -f $SRC/userpatches/readme.txt
688 echo 'Please read documentation about customizing build configuration' > $SRC/userpatches/README
689 echo 'http://www.armbian.com/using-armbian-tools/' >> $SRC/userpatches/README
690 fi
691
692 # check free space (basic)
693 local freespace=$(findmnt --target $SRC -n -o AVAIL -b 2>/dev/null) # in bytes
694 if [[ -n $freespace && $(( $freespace / 1073741824 )) -lt 10 ]]; then
695 display_alert "Low free space left" "$(( $freespace / 1073741824 )) GiB" "wrn"
696 # pause here since dialog-based menu will hide this message otherwise
697 echo -e "Press \e[0;33m<Ctrl-C>\x1B[0m to abort compilation, \e[0;33m<Enter>\x1B[0m to ignore and continue"
698 read
699 fi
700 }
701
该函数的功能主要：由于armbian的开发环境只支持ubuntu 16.04 18.04,且必须在64位机器上面安装，开发环境需要安装相关的软件包，通过查询已安装的软件包，然后把缺失的软件包都安装上
由于我们不是在docker容器当中编译，所以不必关心561-575行的内容，609-613行会同步网络时间，
619-625行，在本机挂载arm rootfs是需要binfmt_mist驱动的支持，参考:https://en.wikipedia.org/wiki/Binfmt_misc
Miscellaneous Binary Format（binfmt_misc）机制，可以通过要打开文件的特性来选择到底使用哪个程序来打开，该机制根据文件的元属性来选择合适的程序将其打开。
627-639行，创建相关的目录结构
645-664行，下载工具链
682行， 下载etcher_cli工具
692-700行，用于检测硬盘空间是否足够搭建开发环境
继续回到lib/mian.sh
79 # if KERNEL_ONLY, KERNEL_CONFIGURE, BOARD, BRANCH or RELEASE are not set, display selection menu
80
81 if [[ -z $KERNEL_ONLY ]]; then
82 options+=("yes" "U-boot and kernel packages")
83 options+=("no" "Full OS image for flashing")
84 KERNEL_ONLY=$(dialog --stdout --title "Choose an option" --backtitle "$backtitle" --no-tags --menu "Select what to build" \
85 $TTY_Y $TTY_X $(($TTY_Y - 8)) "${options[@]}")
86 unset options
87 [[ -z $KERNEL_ONLY ]] && exit_with_error "No option selected"
88
89 fi
90
91 if [[ -z $KERNEL_CONFIGURE ]]; then
92 options+=("no" "Do not change the kernel configuration")
93 options+=("yes" "Show a kernel configuration menu before compilation")
94 KERNEL_CONFIGURE=$(dialog --stdout --title "Choose an option" --backtitle "$backtitle" --no-tags --menu "Select the kernel configuration" \
95 $TTY_Y $TTY_X $(($TTY_Y - 8)) "${options[@]}")
96 unset options
97 [[ -z $KERNEL_CONFIGURE ]] && exit_with_error "No option selected"
98
99 fi
100
上面的代码会出对话框图,如下链接对dialog进行讲解，看了之后，上述代码就比较容易理解
https://www.cnblogs.com/lianghong881018/p/10315062.html
其实就是弹出如下对话框：
x x U-boot and kernel packages x x
x x Full OS image for flashing x x
x x Do not change the kernel configuration x x
x x Show a kernel configuration menu before compilation x x
在lib/main.sh
101 if [[ -z $BOARD ]]; then
102 WIP_STATE=supported
103 WIP_BUTTON='CSC/WIP/EOS'
104 STATE_DESCRIPTION=' - Officially supported boards'
105 temp_rc=$(mktemp)
106 while true; do
107 options=()
108 if [[ $WIP_STATE == supported ]]; then
109 for board in $SRC/config/boards/*.conf; do
110 options+=("$(basename $board | cut -d'.' -f1)" "$(head -1 $board | cut -d'#' -f2)")
111 done
112 else
113 for board in $SRC/config/boards/*.wip; do
114 options+=("$(basename $board | cut -d'.' -f1)" "\Z1(WIP)\Zn $(head -1 $board | cut -d'#' -f2)")
115 done
116 for board in $SRC/config/boards/*.csc; do
117 options+=("$(basename $board | cut -d'.' -f1)" "\Z1(CSC)\Zn $(head -1 $board | cut -d'#' -f2)")
118 done
119 for board in $SRC/config/boards/*.eos; do
120 options+=("$(basename $board | cut -d'.' -f1)" "\Z1(EOS)\Zn $(head -1 $board | cut -d'#' -f2)")
121 done
122 fi
123 if [[ $WIP_STATE != supported ]]; then
124 cat <<-'EOF' > $temp_rc
125 dialog_color = (RED,WHITE,OFF)
126 screen_color = (WHITE,RED,ON)
127 tag_color = (RED,WHITE,ON)
128 item_selected_color = (WHITE,RED,ON)
129 tag_selected_color = (WHITE,RED,ON)
130 tag_key_selected_color = (WHITE,RED,ON)
131 EOF
132 else
133 echo > $temp_rc
134 fi
135 BOARD=$(DIALOGRC=$temp_rc dialog --stdout --title "Choose a board" --backtitle "$backtitle" --scrollbar --colors \
136 --extra-label "Show $WIP_BUTTON" --extra-button --menu "Select the target board. Displaying:\n$STATE_DESCRIPTION" \
137 $TTY_Y $TTY_X $(($TTY_Y - 8)) "${options[@]}")
138 STATUS=$?
139 if [[ $STATUS == 3 ]]; then
140 if [[ $WIP_STATE == supported ]]; then
141 [[ $SHOW_WARNING == yes ]] && show_developer_warning
142 STATE_DESCRIPTION=' - \Z1(CSC)\Zn - Community Supported Configuration\n - \Z1(WIP)\Zn - Work In Progress\n - \Z1(EOS)\Zn - End Of Support'
143 WIP_STATE=unsupported
144 WIP_BUTTON='supported'
145 else
146 STATE_DESCRIPTION=' - Officially supported boards'
147 WIP_STATE=supported
148 WIP_BUTTON='CSC/WIP/EOS'
149 fi
150 continue
151 elif [[ $STATUS == 0 ]]; then
152 break
153 fi
154 unset options
155 [[ -z $BOARD ]] && exit_with_error "No board selected"
156 done
157 fi
158
159 if [[ -f $SRC/config/boards/${BOARD}.conf ]]; then
160 BOARD_TYPE='conf'
161 elif [[ -f $SRC/config/boards/${BOARD}.csc ]]; then
162 BOARD_TYPE='csc'
163 elif [[ -f $SRC/config/boards/${BOARD}.wip ]]; then
164 BOARD_TYPE='wip'
165 elif [[ -f $SRC/config/boards/${BOARD}.eos ]]; then
166 BOARD_TYPE='eos'
167 fi101-157行， 通过枚举$SRC/config/boards/下的文件，弹出对话框，来设置BOARD变量。
x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqk x
x x bananapi A20 dual core 1Gb SoC x x
x x bananapim2plus H3 quad core 1Gb SoC Wifi x x
x x bananapipro A20 dual core 1GB SoC WiFi x x
x x beelinkx2 H3 quad core 1GB SoC WiFi eMMC x x
x x clearfogbase Marvell Armada 38x 1xmPCIe M.2 2xGBE SFP x x
x x clearfogpro Marvell Armada 38x 2xmPCIe M.2 GBE Switch SFP x x
x x cubietruck A20 dual core 2Gb SoC Wifi x x
x x cubox-i Freescale iMx dual/quad core Wifi x x
x x espressobin Marvell Armada 37x 1xmPCIe 2xGBE x x
x x helios4 Marvell Armada 388 2GB-ECC 4xSATA 2xUSB3.0 1xGBE x x
x x iotx-3 AM335X 1Gb SoC eMMC x x
x x lepotato S905x Le potato quad core 2Gb SoC eMMC x x
x x lime2 A20 dual core 1Gb SoC eMMC x x
x x lime-a33 A33 quad core 1Gb SoC x x
x x lime A20 dual core 512Mb SoC x x
x x micro A20 dual core 1Gb SoC eMMC x x
x x miqi RK3288 quad core 2GB SoC GBE x x
x x nanopiair H3 quad core 512MB SoC Headless WiFi/BT eMMC x x
x x nanopiduo H2+ quad core 256/512MB SoC Wi-Fi/Ethernet x x
x x nanopik1plus H5 quad core 2GB RAM Wifi GBE eMMC x x
x x nanopik2-s905 S905 K2 quad core 2GB SoC WiFi eMMC x x
x x nanopim1 H3 quad core 1Gb SoC x x
x x nanopim1plus H3 quad core 1GB SoC GbE/WiFi/BT eMMC x x
x x nanopineo2 H5 quad core 256/512MB SoC Headless GBE x x
x x nanopineo H3 quad core 256/512MB SoC Headless x x
x x nanopineocore2 H5 quad core 1GB SoC Headless GBE eMMC x x
x x nanopineoplus2 H5 quad core 1GB SoC Headless GBE eMMC WiFi/BT x x
x x odroidc1 S805 C1 quad core x x
x x odroidc2 S905 C2 quad core x x
x x odroidxu4 Exynos5422 XU3/XU4 octa core x x
x x orangepi2 H3 quad core 1GB RAM x x
x x orangepilite H3 quad core 512MB RAM WiFi x x
x x orangepione H3 quad core 512MB RAM x x
x x orangepipc2 H5 quad core 1GB RAM x x
x x orangepipc H3 quad core 1GB RAM x x
x x orangepipcplus H3 quad core 1GB RAM WiFi eMMC x x
x x orangepiplus2e H3 quad core 2GB RAM WiFi eMMC x x
x x orangepiplus H3 quad core 1GB/2GB RAM WiFi eMMC x x
x x orangepiprime H5 quad core 2GB RAM Wi-Fi/BT x x
x x orangepi-r1 H2+ quad core 256MB Wi-Fi + dual Ethernet x x
x x orangepiwin A64 quad core 1GB SoC GBE WiFi x x
x x orangepizero H2+ quad core 256/512MB SoC Wi-Fi/Ethernet x x
x x orangepizeroplus2-h3 H3 quad core 512MB SoC Wi-Fi/BT x x
x x orangepizeroplus2-h5 H5 quad core 512MB SoC Wi-Fi/BT x x
x x orangepizeroplus H5 quad core 512MB RAM, GbE, Wi-Fi x x
x x pine64 A64 quad core 512MB-2GB SoC GBE x x
x x pine64so A64 quad core 2GB SoC GBE x x
x x pinebook-a64 A64 quad core 2GB SoC Wi-Fi/BT x x
x x rock64 RK3328 quad core SoC 1GB-4GB x x
x x tinkerboard RK3288 quad core 2GB SoC GBE WiFi x x
x x udoo Freescale iMx dual/quad core Wifi x x
x x x x
x x x x
x x x x
x x x x
x x x x
x x x x
159-167行，根据$BOARD变量来设置BOARD_TYPE的值。
停一停，到了这一步，其实已经知道我们到底编译的是哪块板子了。接下来就是读取相关的配置。
把uboot kernel相关代码拉下来，并选择对应的rootfs版本，如ubuntu debian等，打包最终的镜像
当然到此处我们也知道如果要自已添加对新板子的支持，$SRC/config/boards/$BOARD.｛conf,csc,wip,eos｝是必不可少的。
来源：oschina
链接：https://my.oschina.net/u/4324410/blog/3646221