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Appendix A BSP User Guide
28
Appendix A
Storage Partitions
The layout of the MMC/SD card or eMMC for Android system is showed below.
• [Partition type/index] is defined in the MBR.
• [Name] is only meaningful in android, you can ignore it when creating these partitions.
• [Start Offset] shows where partition is started, unit in MBytes.
The SYSTEM partition is used to put the established android system image. The DATA is used
to put application’s unpacked codes/data, the database of system configurations, etc. In the
normal boot mode, the root file system is mounted from uRamdisk. In the recovery mode, the
root file system is mounted from the REOVERY partition.
Partition
Type/Index
Name
Start Offset
Size
File System
Content
N/A
BOOT
0
10MB
N/A
bootloader/kernel/
uramdisk images
Primary 1
MEDIA
10MB
User
Defined
VFAT. Mount as/
sdcards
Media file storage
Primary 2
SYSTEM
follow MEDIA
≥
200MB
EXT4. Mount as/
system (with read
only)
Android system bin/
libs (system.img)
Logic 5
(Extended 3)
DATA
follow SYSTEM > 200MB EXT4. Mount as/
data
Android data
(e.g. installed app)
Logic 6
(Extended 3)
CACHE
follow DATA
> 10MB
EXT4. Mount as/
cache
Android cache
Primary 4
RECOVERY follow CACHE
> 20MB
EXT4. Mount as/
in recovery mode
Root file system
for recovery mode
(recovery.img)
To create these partitions, you can simply use the MFG tool described in the next section, or
use the fdisk utility on Linux PC.
After creating the partition by fdisk, please format each file system via the following
commands:
# mkfs.vfat /dev/sdx1
# mkfs.ext4 /dev/sdx2 -O ^extent -L system
# mkfs.ext4 /dev/sdx4 -O ^extent -L recovery
# mkfs.ext4 /dev/sdx5 -O ^extent -L data
# mkfs.ext4 /dev/sdx6 -O ^extent -L cache
Note:
/dev/sdxN, the x is the disk index from ‘a’ to ‘z’, that may be different from each
Linux PC.
