2011-04-06

32 bit apps, Windows x64 and the System32 directory

While adding a hidden magic key feature to Zadig, that deletes the libusb-1.0 DLLs that are installed by the libusbK driver in System32\ and SysWOW64\ (when you are developing for both libwdi and libusb, the multiplication of libusb DLLs becomes a major issue), I found that a 32 bit Zadig application running on x64 Windows would not see the libusb-1.0.dll residing in System32\.

The reason for that is that, from a 32 bit app perspective, Windows maps SysWOW64\ (the directory that, as its name does NOT indicate, contains 32 bit binaries) to System32\, and therefore trying to access the actual System32\ (the directory that contains 64 bit binaries) using %WINDIR%\System32.

If for any reason you want to access the actual System32\ directory from a 32 bit application running on Windows x64, you have to use Sysnative (eg: C:\Windows\Sysnative).

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