An open source OS makes debugging applications so much easier. Instead of firing up IDA and going through opcodes, you can simply read the code and sometimes even find comments. However, searching through millions of lines of code can be a daunting task. Operation systems usually have a huge codebase and even the simple task of looking for one function can take a few good minutes. After reading that function, you usually want to search for functions it calls or functions that call it to better understand the flow. Those extra searches take time too. A good IDE would solve this issue but it requires downloading and indexing the massive source code first.

LXR was created for this exact reason. It allows hosting a fully indexed copy of the source code. It even makes it easy to publish an index of multiple versions of the source code. Want to compare a certain function between two versions of the Linux kernel? No problem. Want to know which functions use a certain function? Easy. LXR is awesome and fast.

Setting up LXR on your own, however, does take some time and effort. That is why I was happy to find AndroidXref.com while trying to hunt down a bug in one of my Android applications. It indexes both Android and patched Linux kernel sources for all major versions of Android. It is an invaluable resource every Android developer should know.

I originally had a question about this topic open on StackOverflow with AndroidXref as the accepted answer. It was recently deleted, probably because it didn’t have anything to do with C operator precedence. This is my AndroidXref.SEO++.