Is it possible to install a 32 bit OS on a 64 bit machine ... then access the 64 bit registers while in 32-bit land?
No.
...But the 64-bit OS does support native 32-bit modules, correct? Probably at an abstraction layer or something.
Yes.
:)
Quote from: Mark Jones on October 22, 2007, 03:34:27 PM
...But the 64-bit OS does support native 32-bit modules, correct? Probably at an abstraction layer or something.
Microsoft calls its abstraction layer Windows On Windows (WOW64)
I do not believe that a 32-bit program running under WOW64 can load and call 64-bit DLL's .. can anyone confirm?
Thomas,
It would be good to access the 64-bit registers in the 32-bit environment for optimization purposes but probably that's not possible.
No probably about it - the x86-64 registers are not addressible while in 32-bit mode .. this includes the extended SSE register set (xmm8 .. xmm15)