What DLLMain lpReserved parameter really mean?
dll, internals, winapi, windows
Solution
The quote in the question contains all the information that you are permitted to rely on:
If fdwReason is DLL_PROCESS_ATTACH, lpvReserved is NULL for dynamic loads and non-NULL for static loads.
All you are entitled to do is treat `lpvReserved` as a boolean that signals information about whether the load is dynamic or static (aka implicit).
It's perfectly plausible that there are versions of Windows for which `lpvReserved` carries more information that a plain boolean. However, that is a private implementation detail and you should not rely on that.
Problem
One of well-known DLLMain function parameters is LPVOID lpvReserved. From MSDN documentation: If fdwReason is DLL_PROCESS_ATTACH, lpvReserved is NULL for dynamic loads and non-NULL for static loads. But what lpReserved really mean? Is pointer to somenthing?