On Mon, 20 Jun 2011, Nicolas Pitre wrote: > On Mon, 20 Jun 2011, Alan Stern wrote: > > > On Mon, 20 Jun 2011, Nicolas Pitre wrote: > > > > > > As far as I can tell, the other structures in ehci.h have > > > > ((aligned(32)) simply in order to save space, since there can be large > > > > numbers of these structures allocated. > > > > > > How can increasing the alignment to 32 bytes save space? > > > > No, no -- the alignment is _decreased_ to 32 bits. Without the > > attribute the alignment would have been 64 bits. > > The aligned attribute requires a byte value not a bit value. > Maybe what you meant is ((aligned(4)) ? Ah, very good point! No, I meant ((aligned(32))). Do "grep aligned drivers/usb/host/ehci.h" and you'll see. So my understanding was wrong; these structure really are being forced to a strict alignment. And indeed, now that I go back and look at the EHCI spec, it turns out that this alignment is required by the hardware. Okay, so this digression was irrelevant to our discussion. Forget I mentioned it... Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
