[20091225]Android Porting Guide（4）vold

Andorid use vold to manage SD card and it is easy to use.

But I meet many troubles and finally find that the real problem is in the Linux Kernel.

Thanks to the Android Mail List.

Part I (kernel)

(1)make sure thus kernel configuration in MMC driver

CONFIG_MMC=y

# CONFIG_MMC_DEBUG is not set

CONFIG_MMC_UNSAFE_RESUME=y

# CONFIG_MMC_EMBEDDED_SDIO is not set

CONFIG_MMC_PARANOID_SD_INIT=y

#

# MMC/SD Card Drivers

#

CONFIG_MMC_BLOCK=y

CONFIG_MMC_BLOCK_BOUNCE=y

# CONFIG_MMC_BLOCK_PARANOID_RESUME is not set

# CONFIG_SDIO_UART is not set

# CONFIG_MMC_TEST is not set

#

# MMC/SD Host Controller Drivers

#

CONFIG_MMC_SDHCI=y

  

(2)Disable this option 

General Setup ->  Create deprecated sysfs layout for older userspace tools 

Before I did this,vold showed a lot of trouble.

And ,my media_path is not right 

media_path  /devices/platform/s3c-sdhci.0/mmc_host:mmc0<--my path before turn off that option

media_path  /devices/platform/s3c-sdhci.0/mmc_host/mmc0 <--this is the right one

Vold may be unhappy to accept my old path,and it didn't work.

D/vold    (   42): Accepted connection from framework

D/vold    (   42): dispatch_cmd(send_ums_status):

D/vold    (   42): dispatch_cmd(mount_volume:/sdcard):

E/vold    (   42): Cannot start volume '/sdcard' (volume is not bound)

D/MountListener(   59): handleEvent volume_nomedia:/sdcard

D/MountListener(   59): handleEvent ums_disabled

D/MountListener(   59): handleEvent ums_disconnected 

(3) rebuild your linux kernel

PART II(android system)

(1) creat a vold.conf in build/target/board/idea6410

## vold configuration file for idea6410

volume_sdcard {

    ## This is the direct uevent device path to the SD slot on the device

media_path  /devices/platform/s3c-sdhci.0/mmc_host/mmc0

    media_type     mmc

    mount_point    /sdcard

    ums_path       /devices/platform/usb_mass_storage/lun0

}

(2)add those below to AndroidBoard.mk

include $(CLEAR_VARS)

LOCAL_MODULE_CLASS := ETC

LOCAL_MODULE := vold.conf

LOCAL_SRC_FILES := $(LOCAL_MODULE)

include $(BUILD_PREBUILT)

(3)rebuild the system and check init.rc

service vold /system/bin/vold

    socket vold stream 0660 root mount

(4)enjoy

D/vold    (   42): Accepted connection from framework

D/vold    (   42): dispatch_cmd(send_ums_status):

D/vold    (   42): dispatch_cmd(mount_volume:/sdcard):

I/vold    (   42): Evaluating dev '/devices/platform/s3c-sdhci.0/mmc_host/mmc0/mmc0:e624/block/mmcblk0' for mountable filesystems for '/sdcard'

D/MountListener(   61): handleEvent volume_unmounted:/sdcard

D/MountListener(   61): handleEvent ums_disabled

D/MountListener(   61): handleEvent ums_disconnected

D/MountListener(   61): handleEvent volume_checking:/sdcard

Rockie Cheng

阿虚