User`s guide

Porting the Android Kernel
i.MX53 System Development User’s Guide, Rev. 1
Freescale Semiconductor 12-5
12.4 Modifying the init.rc Partition Locations
The init.rc file mounts the three main partitions—system, cache, and data—on the image. By default, these
partitions are mounted from the SD/MMC controller.
If you have these partitions stored on another Flash source, modify the following lines to choose from the
specific NVM.
• To mount the /system directory:
mount ext3 /dev/block/mmcblk0p2 /system
mount ext3 /dev/block/mmcblk0p2 /system ro remount
• To mount the /data directory:
mount ext3 /dev/block/mmcblk0p5 /data nosuid nodev
• To mounts the /recovery directory:
mount ext3 /dev/block/mmcblk0p6 /cache nosuid nodev
You also can modify the partition number where the directories and files are stored.
12.5 Adding Android Enhancements
Most Android porting is performed on the kernel side, as shown in Figure 12-3.
Figure 12-3. Linux Kernel
Android adds enhancements to the Linux kernel in order to give upper layers services like interprocess
communication and power management policies. Table 12-1 shows the enhancements.
Table 12-1. Android Enhancements
Enhancement Purpose
Alarm Provide timers functionality to wake up and sleep the device
Ashmem Asynchronous shared memory share memory across process.
Binder Ipc binder driver for interprocess communication
Power Management New stack power management to increase performance
Low Memory Killer Provides the functionality for android memory management
Kernel Debugger Debug purposes
Logger Debug purposes