Android 使用EMMC FS的问题
Android 使用EMMC FS的问题
由于项目一直使用老旧的Android 2.3.4,然后硬件加入了EMMC所以system和userdata的image格式也相应的由yaffs2变成了EXT4。在调试过程中由此产生了两个问题:
一,image的生成问题:更改build/core下的Makefile。
以生成system.img.ext4为例,将原有的build-systemimage-target增加一行。相应的需要在device的BoardConfig.mk中根据EMMC分区定义BOARD_SYSTEMIMAGE_PARTITION_SIZE,定义tag TARGET_SYSTEMIMAGES_USE_EXT4作为开关。
- ifeq ($(INTERNAL_USERIMAGES_USE_EXT),true)
- ifeq ($(TARGET_SYSTEMIMAGES_USE_EXT4),true)
- define build-systemimage-target
- @echo "Target system fs image: $(1)"
- $(call build-userimage-ext-target,$(TARGET_OUT),$(1),system,$(INTERNAL_USERIMAGES_EXT_VARIANT),$(BOARD_SYSTEMIMAGE_PARTITION_SIZE))
- @echo "Using my script"
- $(MAKE_EXT4FS) -l $(BOARD_SYSTEMIMAGE_PARTITION_SIZE) -a system $(PRODUCT_OUT)/system.img.ext4 $(TARGET_OUT)
- endef
- else
- ## generate an ext2 image
- # $(1): output file
- define build-systemimage-target
- @echo "Target system fs image: $(1)"
- $(call build-userimage-ext-target,$(TARGET_OUT),$(1),system,$(INTERNAL_USERIMAGES_EXT_VARIANT),$(BOARD_SYSTEMIMAGE_PARTITION_SIZE))
- endef
- endif # TARGET_SYSTEMIMAGES_USE_EXT4
- else # INTERNAL_USERIMAGES_USE_EXT != true
刚开始调试的时候进adb shell曾经报“exec - /system/bin/sh not found”错误,系统加载不成功。但是$(TARGET_OUT)目录下是完整的,因此应该是文件系统没有mount成功。init.rc中关于文件系统的片段如下:
- on fs
- # mount mtd partitions
- # Mount /system rw first to give the filesystem a chance to save a checkpoint
- mount yaffs2 mtd@system /system
- #mount yaffs2 mtd@system /system ro remount
- mount yaffs2 mtd@userdata /data nosuid nodev
- mount yaffs2 mtd@persist /persist nosuid nodev
- mount yaffs2 mtd@cache /cache nosuid nodev
- mount yaffs2 mtd@persist /persist nosuid nodev
- on emmc-fs
- wait /dev/block/mmcblk0p10
- mount ext4 /dev/block/mmcblk0p19 /system rw barrier=1
- chmod 0777 /system/bin/ext4check.sh
- #
- wait /dev/block/mmcblk0p11
- exec /system/bin/sh -c "/system/bin/fixebr.sh mmcblk0"
- exec /system/bin/sh -c "/system/bin/ext4check.sh USERDATA /dev/block/mmcblk0p22"
- mount ext4 /dev/block/mmcblk0p22 /data nosuid nodev barrier=1
- #
- wait /dev/block/mmcblk0p12
- exec /system/bin/sh -c "/system/bin/ext4check.sh PERSIST /dev/block/mmcblk0p10"
- mount ext4 /dev/block/mmcblk0p10 /persist nosuid nodev barrier=1
- #
- wait /dev/block/mmcblk0p13
- exec /system/bin/sh -c "/system/bin/ext4check.sh CACHE /dev/block/mmcblk0p21"
- mount ext4 /dev/block/mmcblk0p21 /cache nosuid nodev barrier=1
- action_for_each_trigger("init", action_add_queue_tail);
- action_for_each_trigger("early-fs", action_add_queue_tail);
- action_for_each_trigger("fs", action_add_queue_tail);
- action_for_each_trigger("post-fs", action_add_queue_tail);
- action_for_each_trigger("init", action_add_queue_tail);
- action_for_each_trigger("early-fs", action_add_queue_tail);
- action_for_each_trigger("emmc-fs", action_add_queue_tail);
- action_for_each_trigger("post-fs", action_add_queue_tail);
另外还有一个小问题,/data/目录有时候会写不进去东西导致dalvik虚拟机不能把cache放进去一直启动不成功,在init.rc中把 mount rootfs rootfs / ro remount 这句从on post-fs的开始移动到init.rc的最后,这样就能保证先把/data分区里面必须的目录都建立好了再锁住。
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