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In this article Xiaobian for you to introduce in detail "how to achieve rom migration in Android", the content is detailed, the steps are clear, the details are handled properly, I hope this "how to achieve rom migration in Android" article can help you solve your doubts, the following follow the editor's ideas slowly in depth, together to learn new knowledge.

1 ROM contains two basic image, one is boot.image, this image is mainly kernel and something under the file system / directory. I won't talk about kernel. / the directory is mainly init and related configuration files.

System.image is the core of the userpace of the android system, including something under / system/bin,system/lib,system/app.

2 mobile phones, different mobile phones, their internal use of chips, configuration and so on are different. In addition, the android source code does not contain hardware-related code. In other words, it's okay to just run on the simulator with the standard source code.

Get the real machine, run may be able to run, but also use the mobile phone as a simulator, the phone, audio,wifi and other hardware-related can not be used. There is no reason for this. The hardware-related driver is the manufacturer's closed source code.

It's absolutely impossible to let it out. However, the binary HAL layer so that comes with some htc/sumsing in android is also copied into system.image when compiling the corresponding device.

Therefore, based on the above understanding, brothers do not want to use the standard source code to make a serious rom. In addition, mobile phones can be divided into AP/BP, and the code of BP is another set, which is equivalent to another OS for

Modem communicates. Even if you can handle AP,BP, don't think about it.

3. How did CM come out? CM is not an immortal. I estimate that its work can be divided into the following:

1 boot.image, it is possible to be directly based on the manufacturer. For example, in the HTC G7 migration, G7 official ROM is used directly.

In 2 system,image, hardware-independent (that is, non-HAL layer code) can be changed as much as you like.

3 system.image, related to hardware, first get the official so through adb pull, and then put it into your own ROM. The work here is difficult, but in theory it is possible to be binary compatible.

As can be seen from the above, if the official does not provide 4. 0 ROM,CM, it will be closed. (I personally think that we can actually use so of 2.3 in 4.0. the method can be loaded by dlopen, with a layer of isolation in the middle. But if

If the dependent header file changes, the workload will be heavy.)

4 MIUI, dim sum OS, is the secondary development on top of CM. Chinese borrowlism has created companies such as MIUI and dim sum that are clamoring to be ROM.

To sum up, brothers, don't think about building an awesome ROM on your own, it's unnecessary and meaningless.

For those who want to engage in rom, it is recommended to do secondary development on the basis of CM, and do not move anything related to hardware.

2 if you want to change the ui, you can also change the picture based on the existing system.image, and then package it into image.

Read here, this "how to achieve rom migration in Android" article has been introduced, want to master the knowledge of this article also need to practice and use to understand, if you want to know more about the article, welcome to follow the industry information channel.

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