On Mon, 16 Apr 2012, Norman Diamond wrote: > Alan Stern wrote: > > On Fri, 13 Apr 2012, Norman Diamond wrote: > >> You THOUGHT you knew in advance that a particular bridge is known > >> to have the overreporting but, where in fact in some secret > >> revisions it doesn't and in some secret revisions we're not quite > >> sure, missing a log and missing a test sample for further > >> testing.� How can we be sure that other bridge manufacturers don't > >> also make secret revisions? > > > > In fact we don't know.� But that's not a good enough reason to risk > > breaking existing systems.� When we encounter bridges whose > > behavior has changed, we can update the quirk entries. > > That's not a good enough reason to cause known breakage in newer > existing systems, but I agree that updating the quirk entries helps > solve it. > > > (Even that isn't as cautious as I'd like.� If the device behavior > > has changed then maybe the old devices won't handle reading beyond > > the end of the drive.� But I can't think of anything safer.) > > Well, if the reported capacity isn't a multiple of 63 and if no > existing partition includes the last reported block then it seems > comparatively safe to decrement the reported size, but as you pointed > out, we can't really be sure what the existing partitions are > (non-DOS tables etc.). But a multiple of 63 still seems like a > relatively safe heuristic, comparatively speaking. But not always, > as you pointed out, and as I'll detail below. At this point I'm not sure what you want to do. Would you like the quirks entry for your bridge changed to CAPACITY_HEURISTICS instead of FIX_CAPACITY? That's the easiest thing to do quickly. 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
