Modern architecture research relies heavily on applicationlevel detailed pipeline simulation. A time consuming part of building a simulator is correctly emulating the operating system effects, which is required even if the goal is to simulate just the application code, in order to achieve functional correctness of the application’s execution. Existing applicationlevel simulators require manually hand coding the emulation of each and every possible system effect (e.g., system call, interrupt, DMA transfer) that can impact the application’s execution. Developing such an emulator for a given operating system is a tedious exercise, and can also be costly to maintain it to support newer versions of that operating system. Furthermore, porting the emulator to a completely differ operating system might involve building it all together from scratch. In this paper, we describe a tool that can automatically log operating system effects to guide architecture simulation of application code...