Analysis of Ota update and restart on Ti Platform

These days I have been wondering how the adroid system restarts from the main system to the recovery. Different hardware platforms may have different practices. Most of the practices mentioned on the Internet are writing MISC partition BCB. However, I found that my mobile phone is not. First, I will introduce my platform version:

Hardware Platform:Ti omap4460

Android:The native ecology 4.0.3 of the ndroid system.

After I enter the recovery mode, manually write the reboot to the recovery command to the MISC partition, power off, read the MISC partition, and confirm that the write is correct,

Restart the phone and find that the phone has not entered the recovery mode. Is it swollen?

There is only one way: view the source code. I found that every restart from main sytem to recovery is a hot start, and uboot will view a system's internal RAM
Public_sar_ram_1_free. If the system Ram contains the "recovery" string, the system enters the recovery mode. Finally, find the cause. I don't know how other platforms are implemented.