More specifically, it turns out that the 64-bit version of this system call is no longer the same name as the 32-bit version on Python 2.5...or at least, that's what I gathered from Bug 86685.
More specifically, it turns out that the 64-bit version of this system call is no longer the same name as the 32-bit version on Python 2.5...or at least, that's what I gathered from Bug 86685.