When performing KD(Kernel Debugging) in Windows with Windbg if you have to set a break point in a user mode process we should always use .process /i address; g; .reload /user. Lot of good content is written on the internet on this command, but nothing seemed to explain why this command should be used instead of the familiar .process /r /p address. I would like to shed some light on this. Before reading any further I would strongly encourage you to read about it from above link. In this article I assume some basic knowledge on how kernel debugging is done with Windbg. Also, I would like to start with the following question.
If the debugger has read/write access to the user mode process via .process /r /p why cannot it insert int 3 in user mode process when performing KD? Why do we have to make the user mode process the current process context by running .process /i ?