I wonder, is it safe to import WinAPI functions by their ordinals? AFAIK Micro$oft don’t guarantee that this method will work in their future OS’es, but what about existing OS’es that belong to win32 family? Will ordinals for some functions exported by KERNEL32.DLL and USER32.DLL in Windows XP SP2 be the same ordinals exported by the same DLL’s in, let’s say, Windows 98?

Probably, since the C lib's use ordinals (as far as I could tell.)

UCM: can you give some examples?

Well, I looked at the import section of an executable I had linked from an OBJ (from FASM), and there were no human-readable names there.

wasn't it that you linked to LIBCDLL.DLL with ordinals? not to kernel32.dll etc? and LIBCDLL.DLL uses strings, not ordinals...

I did not link to the C library, only to the system DLL's (kernel32 and user32.)

Whether it is safe? Here there is only one way - most to check up To take DLL from, say, WinXP and Win98, and to look ordinals on interesting you API. But anyway, if MicroSoft speaks, that such support will not be conducted, to mean so it and will be. So it is better to not experiment, that then it was not need to rewrite a code.

It's not safe. See http://blogs.msdn.com/oldnewthing/archive/2006/07/18/669668.aspx

Also read http://blogs.msdn.com/oldnewthing/archive/2006/07/28/681473.aspx about efficiency of ordinal-based imports. BTW, FASM does not set a look-up hint, while Microsoft's linker (in MASM or VC++) sets it.

So there is no way to use FASM with ordinals ?

No, the way is. Manual loading API by means of GetProcAddress.

...or using object module output, and link against import libraries with ordinals.

The "import" macro is capable of importing functions by ordinal (see Win32 headers docs). However the "export" macro currently doesn't allow you to set up the fixed ordinals in your own DLL.