64 bit compilation in visual studio

Question

I am compiling a DLL that uses ATL to house a com object and targeting X64. Everything seems to be fine but the DLL wont run on the 64 bit machine. I ran depends on it on the target machine and it seems to be dependant on the x86 versions of countless system libraries (kernel32 etc.). Anyone know what i am missing?

Answer 1

Need more details to be able to help, What are the errors you are getting?

The name of a DLL does not indicate if it's 64 bit or not, in windows there are versions of most system dlls on both 32 & 64 bits and they are named the same but placed in different folders.

Answer 2

The results you got from depends are troubling. Are you sure your DLL is indeed 64 bit? If it is, and it is linked to 32 bit DLLs, it will never work. Go back to your dev env and change those dependencies. If your DLL happens to actually be 32 bit, look for the 64 bit one...

You don't specify how exactly the DLL won't run (does regsvr32 work? if so, what error does creating an instance return?). In case you can indeed register it and you're trying to use it from a 32 bit client, make sure you specify the activation bitness correctly (see CLSCTX_ACTIVATE_32_BIT_SERVER and CLSCTX_ACTIVATE_64_BIT_SERVER). If this is the case, the dependency thing was a red herring, of course.

Answer 3

I am guessing you are running the x86 version of Dependency Walker, which when analyzing a 64 bit DLL will show that it depends upon several x86 system libraries. You need to download and run the x64 version of Dependency Walker to see what is really causing the problem with your DLL.

http://www.dependencywalker.com