Android has been a variant of Linux for many years. The release of Linux 3.3 makes the two become one again.

Android has always been Linux, but it has been developing independently for many years, and its code has not been integrated into mainstream Linux. Linus Torvalds, the originator and chief developer of Linux, hopes that Android will officially return to Linux.

The dispute between Android and Linux originated in the autumn of 21, when Patrick Brady, a Google engineer, said that Android was not Linux. But this is not the case. In essence, Android is Linux.

Google has established a policy that Android is not compatible with the mainstream Linux kernel. Greg Kroah-Hartman, a Linux kernel maintenance engineer of the Linux Foundation and the head of the Linux Driver Project, said, "Android kernel code is not just some drivers in the drivers/staging/android directory. The normal operation of Android system needs the lock type newly developed by Google and the hook in the core system. To develop hardware drivers for Android, developers need to use the new lock and strange security mode correctly. In addition, Android also uses a completely different frame buffer driver interface. "

the differences between p>Android and Linux come from many aspects. One of them is that Google's Android development team solves the energy consumption problem in an autonomous way; Another factor is that the Android team is busy developing the details of Android devices, and it is not good enough to cooperate with the Linux core team.

There is a lot of debate in the developer community about how to properly handle Android-specific code in Linux. As a result of the debate, Torvalds excluded Android drivers from the Linux kernel at the end of 29.

despite the differences between the Android team and the Linux team, Android has never faced the risk of being sued by the Linux team for violating GPLv2. Torvalds once said that the statement that Android violates GPL is "completely wrong".

Torvalds said last autumn, "Although there is still a lot of work to be done, Android and Linux will eventually return to the same kernel, which will not be completed in 4-5 years." Crochmann also said at the time that one of the problems is that "Google's Android team has few staff, tight tasks and limited resources. In the long run, cooperation with us will help them reduce costs." Torvalds said, "We just went in different directions for a while, and in the long run, we will become one, so I have nothing to worry about."

the integration of p>Android and Linux is faster than expected. At the kernel summit last October, Linux kernel developers "agreed that the Android kernel code should be integrated into the mainstream kernel", and thus created the Android Mainlining Project.

Rokhman said in December last year, "When the version 3.3 kernel is released, most of the contents of the Android kernel will be integrated into the mainstream kernel, but there is still a lot of work to be done to better meet the needs of the kernel community, which will take longer."

At present, Android code can be compiled and run in Linux 3.3. But Dick Rokhman pointed out that WakeLocks of Android has not been integrated into the mainstream kernel.