摘要：
1、 系统分区配置和解析过程在Android系统的开发过程中，我们经常遇到添加或调整系统分区大小的问题。让我们以mstar产品为例进行分析。
一、系统分区配置及解析流程
Android系统开发时，经常会遇到添加或者调整系统分区大小的问题，下面以mstar的一款产品（M8386）为例进行分析。
（1）mount指令可以查看到板子中挂载的分区，主要关注ext4类型分区，例如tvservice，tvconfig，tvconfig，tvcustomer ：
sugarcane:/ # mount rootfs on / type rootfs (ro,seclabel) tmpfs on /dev type tmpfs (rw,seclabel,nosuid,relatime,mode=755) devpts on /dev/pts type devpts (rw,seclabel,relatime,mode=600,ptmxmode=000) proc on /proc type proc (rw,relatime) sysfs on /sys type sysfs (rw,seclabel,relatime) selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime) /dev/block/mmcblk0p11 on /system type ext4 (rw,seclabel,relatime,data=ordered) /dev/block/mmcblk0p13 on /vendor type ext4 (rw,seclabel,relatime,data=ordered) debugfs on /sys/kernel/debug type debugfs (rw,seclabel,relatime) none on /acct type cgroup (rw,relatime,cpuacct) none on /dev/stune type cgroup (rw,relatime,schedtune) tmpfs on /mnt type tmpfs (rw,seclabel,relatime,mode=755,gid=1000) none on /config type configfs (rw,relatime) none on /dev/cpuctl type cgroup (rw,relatime,cpu) none on /dev/cpuset type cgroup (rw,relatime,cpuset,noprefix,release_agent=/sbin/cpuset_release_agent) pstore on /sys/fs/pstore type pstore (rw,seclabel,relatime) tmpfs on /var type tmpfs (rw,seclabel,relatime,mode=775,gid=1000) /dev/block/mmcblk0p23 on /data type ext4 (rw,seclabel,nosuid,nodev,noatime,data=ordered) /dev/block/mmcblk0p12 on /cache type ext4 (rw,seclabel,nosuid,nodev,noatime,data=ordered) /dev/block/mmcblk0p14 on /tvservice type ext4 (ro,seclabel,relatime,data=ordered) /dev/block/mmcblk0p15 on /tvconfig type ext4 (ro,seclabel,relatime,data=ordered) /dev/block/mmcblk0p16 on /tvdatabase type ext4 (rw,seclabel,nosuid,nodev,noatime,data=ordered) /dev/block/mmcblk0p17 on /tvcustomer type ext4 (rw,seclabel,nosuid,nodev,noatime,data=ordered) /dev/block/mmcblk0p22 on /tvcertificate type ext4 (rw,seclabel,nosuid,nodev,noatime,data=ordered) /dev/block/mmcblk0p18 on /cusswap type ext4 (rw,seclabel,nosuid,nodev,noatime,data=ordered) /dev/block/mmcblk0p19 on /cusdata type ext4 (rw,seclabel,nosuid,nodev,noatime,data=ordered) /dev/block/mmcblk0p21 on /cusparam type ext4 (rw,seclabel,nosuid,nodev,noatime,data=ordered) tmpfs on /storage type tmpfs (rw,seclabel,relatime,mode=755,gid=1000) tracefs on /sys/kernel/debug/tracing type tracefs (rw,seclabel,relatime) /data/media on /mnt/runtime/default/emulated type sdcardfs (rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=1015,multiuser,mask=6,reserved=50MB) /data/media on /storage/emulated type sdcardfs (rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=1015,multiuser,mask=6,reserved=50MB) /data/media on /mnt/runtime/read/emulated type sdcardfs (rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=9997,multiuser,mask=23,reserved=50MB) /data/media on /mnt/runtime/write/emulated type sdcardfs (rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=9997,multiuser,mask=7,reserved=50MB)
（2）查看分区文件 /device/mstar/sugarcane/fstab.m7221 (android平台不同厂商可能名称不一样，但是都是fstab.xxx的形式) ，截取部分信息如下：
/dev/block/platform/mstar_mci.0/by-name/system /system ext4 ro wait,recoveryonly /dev/block/platform/mstar_mci.0/by-name/userdata /data ext4 noatime,nosuid,nodev wait,check /dev/block/platform/mstar_mci.0/by-name/cache /cache ext4 noatime,nosuid,nodev wait,check /dev/block/platform/mstar_mci.0/by-name/vendor /vendor ext4 ro wait,recoveryonly /dev/block/platform/mstar_mci.0/by-name/tvservice /tvservice ext4 ro wait /dev/block/platform/mstar_mci.0/by-name/tvconfig /tvconfig ext4 ro wait /dev/block/platform/mstar_mci.0/by-name/tvdatabase /tvdatabase ext4 noatime,nosuid,nodev wait,check /dev/block/platform/mstar_mci.0/by-name/tvcustomer /tvcustomer ext4 noatime,nosuid,nodev wait,check /dev/block/platform/mstar_mci.0/by-name/tvcertificate /tvcertificate ext4 noatime,nosuid,nodev wait,check
（3）指定各个分区的大小，device/mstar/sugarcane/BoardConfig.mk 文件指定各自大小可以根据需要进行修改
# mmc part # : type name (size) #1. recovery (30M) #2. boot (20M) #3. tee (6M) #4. rtpm (256K) #5. dtb (1M) #6. frc (1M) #7. optee (6M) #8. armfw (64K) #9. system (1200M) #10. userdata (4400M) #11. cache (1G) #12. vendor (300M) #13. tvservice (160M) #14. tvconfig (19M) #15. tvdatabase (8M) #16. tvcustomer (16M) #17. tvcertificate (8M) #18. cm4 (512K) #19. cusswap (5M) #20. cusdata (5M) #21. cusparam (512M) BOARD_RECOVERYIMAGE_PARTITION_SIZE := 0x02000000 BOARD_BOOTIMAGE_PARTITION_SIZE := 0x01400000 BOARD_OPTEEIMAGE_PARTITION_SIZE := 0x00600000 BOARD_ARMFWIMAGE_PARTITION_SIZE := 0x00010000 BOARD_TEEIMAGE_PARTITION_SIZE := 0x00600000 BOARD_RTPMIMAGE_PARTITION_SIZE := 0x00040000 BOARD_DTBIMAGE_PARTITION_SIZE := 0x00100000 BOARD_FRCIMAGE_PARTITION_SIZE := 0x00100000 BOARD_CACHEIMAGE_PARTITION_SIZE := 1073741824 ifeq ($(BOARD_EMMC_FLASH_SIZE),16G) BOARD_SYSTEMIMAGE_PARTITION_SIZE := 2147483648 BOARD_VENDORIMAGE_PARTITION_SIZE := 3221225472 else BOARD_SYSTEMIMAGE_PARTITION_SIZE := 1992294400 BOARD_VENDORIMAGE_PARTITION_SIZE := 419430400 endif BOARD_TVSERVICEIMAGE_PARTITION_SIZE := 0x0A000000 BOARD_TVCONFIGIMAGE_PARTITION_SIZE := 0x01000000 BOARD_TVDATABASEIMAGE_PARTITION_SIZE := 0x00800000 BOARD_TVCUSTOMERIMAGE_PARTITION_SIZE := 0x01000000 BOARD_TVCERTIFICATEIMAGE_PARTITION_SIZE := 0x00800000 BOARD_CM4IMAGE_PARTITION_SIZE := 0x00080000 BOARD_CUSSWAP_PARTITION_SIZE := 5242880 BOARD_CUSDATA_PARTITION_SIZE := 5242880 ifeq ($(BOARD_EMMC_ENLARGE_PARAM),Y) BOARD_CUSPARAM_PARTITION_SIZE := 536870912 else BOARD_CUSPARAM_PARTITION_SIZE := 5242880 endif BOARD_USERDATAIMAGE_PARTITION_SIZE := 817889280 BOARD_FLASH_BLOCK_SIZE := 512
（4）分区调整后在device/mstar/sugarcane/ 下的 fstab.m7221 中指定挂载节点及其他属性，由nit.m7221.rc脚本中on fs 模块启动：
on fs write /proc/sys/vm/page-cluster 0 mount_all /fstab.m7221 swapon_all /fstab.m7221
（5）init进程解析fstab.monet文件，keywords.h文件中注册mount_all操作方法 ：
enum { K_UNKNOWN, #endif KEYWORD(capability, OPTION, 0, 0) KEYWORD(chdir, COMMAND, 1, do_chdir) KEYWORD(chroot, COMMAND, 1, do_chroot) KEYWORD(class, OPTION, 0, 0) KEYWORD(class_start, COMMAND, 1, do_class_start) KEYWORD(class_stop, COMMAND, 1, do_class_stop) KEYWORD(class_reset, COMMAND, 1, do_class_reset) KEYWORD(console, OPTION, 0, 0) KEYWORD(critical, OPTION, 0, 0) KEYWORD(disabled, OPTION, 0, 0) KEYWORD(domainname, COMMAND, 1, do_domainname) KEYWORD(enable, COMMAND, 1, do_enable) KEYWORD(exec, COMMAND, 1, do_exec) KEYWORD(export, COMMAND, 2, do_export) KEYWORD(group, OPTION, 0, 0) KEYWORD(hostname, COMMAND, 1, do_hostname) KEYWORD(ifup, COMMAND, 1, do_ifup) KEYWORD(insmod, COMMAND, 1, do_insmod) KEYWORD(import, SECTION, 1, 0) KEYWORD(keycodes, OPTION, 0, 0) KEYWORD(mkdir, COMMAND, 1, do_mkdir) KEYWORD(mount_all, COMMAND, 1, do_mount_all) KEYWORD(mount, COMMAND, 3, do_mount) KEYWORD(on, SECTION, 0, 0) KEYWORD(oneshot, OPTION, 0, 0) KEYWORD(onrestart, OPTION, 0, 0) KEYWORD(powerctl, COMMAND, 1, do_powerctl) KEYWORD(restart, COMMAND, 1, do_restart) KEYWORD(restorecon, COMMAND, 1, do_restorecon) KEYWORD(restorecon_recursive, COMMAND, 1, do_restorecon_recursive) KEYWORD(rm, COMMAND, 1, do_rm) KEYWORD(rmdir, COMMAND, 1, do_rmdir) KEYWORD(seclabel, OPTION, 0, 0) KEYWORD(service, SECTION, 0, 0) KEYWORD(setcon, COMMAND, 1, do_setcon) KEYWORD(setenforce, COMMAND, 1, do_setenforce) KEYWORD(setenv, OPTION, 2, 0) KEYWORD(setkey, COMMAND, 0, do_setkey) KEYWORD(setprop, COMMAND, 2, do_setprop) KEYWORD(setrlimit, COMMAND, 3, do_setrlimit) KEYWORD(setsebool, COMMAND, 2, do_setsebool) KEYWORD(socket, OPTION, 0, 0) KEYWORD(start, COMMAND, 1, do_start) KEYWORD(stop, COMMAND, 1, do_stop) KEYWORD(swapon_all, COMMAND, 1, do_swapon_all) KEYWORD(trigger, COMMAND, 1, do_trigger) KEYWORD(symlink, COMMAND, 1, do_symlink) KEYWORD(sysclktz, COMMAND, 1, do_sysclktz) KEYWORD(user, OPTION, 0, 0) KEYWORD(wait, COMMAND, 1, do_wait) KEYWORD(write, COMMAND, 2, do_write) KEYWORD(copy, COMMAND, 2, do_copy) KEYWORD(chown, COMMAND, 2, do_chown) KEYWORD(chmod, COMMAND, 2, do_chmod) KEYWORD(loglevel, COMMAND, 1, do_loglevel) KEYWORD(load_persist_props, COMMAND, 0, do_load_persist_props) KEYWORD(load_all_props, COMMAND, 0, do_load_all_props) KEYWORD(ioprio, OPTION, 0, 0) #ifdef __MAKE_KEYWORD_ENUM__ KEYWORD_COUNT, }
builtins.c文件中do_mount_all，启动一个进程调用fs_mgr_read_fstab，fs_mgr_mount_all启动解析，其中systemcorefs_mgr又被vold，adb等模块用来解析fstab.xxx等分区文件。
（6）根据第三步中指定的分区大小，进行打包对应分区的img文件
releaseimage.sh, mkimage.sh, build_image.sh, make_usb_upgrade.sh等脚本(vendormstarcommonscripts目录下)，会根据第三步设置的大小来制作img文件
mkimage.sh
... function make-images() { mkdir -p $RELEASE_OUT mkdir -p $RELEASE_OUT/scripts gernerate-script-start # Raw partition must be first. make-raw-partition make-split-fs-partition system $BOARD_SYSTEMIMAGE_PARTITION_SIZE true make-fs-partition userdata $BOARD_USERDATAIMAGE_PARTITION_SIZE true make-fs-partition cache $BOARD_CACHEIMAGE_PARTITION_SIZE true make-split-fs-partition vendor $BOARD_VENDORIMAGE_PARTITION_SIZE true make-fs-partition tvservice $BOARD_TVSERVICEIMAGE_PARTITION_SIZE false make-fs-partition tvconfig $BOARD_TVCONFIGIMAGE_PARTITION_SIZE false make-fs-partition tvdatabase $BOARD_TVDATABASEIMAGE_PARTITION_SIZE false make-fs-partition tvcustomer $BOARD_TVCUSTOMERIMAGE_PARTITION_SIZE false make-fs-partition tvcertificate $BOARD_TVCERTIFICATEIMAGE_PARTITION_SIZE false if [ "$BOARD_SYSTEMBACKUP" == "true" ]; then split-fs-partition systembackup $BOARD_SYSTEMBACKUPIMAGE_PARTITION_SIZE true fi if [ "$BOARD_CERTIFICATIONIMAGE" == "true" ]; then make-fs-partition certificate $BOARD_CERTIFICATEIMAGE_PARTITION_SIZE false fi # You can make-fs-partition() or make-split-fs-partition() here... ...... }
buiild_image.sh
...... #make-fs-partition $PARTITION_NAME $PARTITION_SIZE $PARTITION_ANDROID function make-fs-partition() { echo -e "