The Android Virtual A/B system is called VAB for short, and I call it a virtual partition.
This series of articles is based on Android R (11) for analysis, unless otherwise specified, it is based on the code version android-11.0.0_r46
Friends who have purchased the "Android Virtual Partition" column, please add me wx to the "Virtual Partition Column VIP Q&A" group, as an additional service of this column, to answer your questions about virtual partitions.
0. Overview
So far, the first two virtual partitions:
"Detailed Explanation of Android Virtual Partition (1) Recommended Reference Materials"
"Detailed Explanation of Android Virtual Partition (2) Virtual Partition Layout"
Some reference materials and virtual partition layout analysis are recommended respectively.
In fact, in order to increase the understanding of the bottom layer of virtual partition snapshots, I wrote two more articles about the principles and practices of linux snapshot snapshots for reference.
This article is based on the official Android document Android_VirtualAB_Design_Performance_Caveats.pdf about the snapshot and merge process, trying to explain to you the state changes of the partition slots during the entire upgrade process.
If you are not familiar with the background of virtual partitions, it is recommended to read Part 1 first