On Mon, Jan 28, 2008 at 02:02:45PM -0700, M. Warner Losh wrote: > : this specific interaction of ABI and processor architecture then it was > : probably found not to implement such a special read because it is messy > : in more than one way. > > When 64-bit operations are enabled, you get all 64-bits. When they > aren't, only the lower 32-bits of the counter are provided (with sign > extension). So when operating in 32-bit mode, saving the upper 32 > bits are not necessary (or even possible). The architecture manual doesn't make a difference between 32-bit and 64-bit for rdhwr. My reading is the entire 64-bit would have to be transfered. Ralf
