On Tue, 23 Mar 2010 10:11:39 -0400 (EDT) Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > Host controller hardware can't handle scatter-gather transfers unless > the boundary between scatterlist elements occurs either at a packet > boundary or at a page boundary -- and in fact, the host controller > drivers don't handle the case where a page boundary isn't also a packet > boundary. > > Because of this restriction, and because high-speed bulk endpoints must > have a maxpacket length of 512, usb-storage (currently the only > scatter-gather USB driver) requires 512-byte alignment of the data > buffers. Any future driver using the scatter-gather library can be > expected to include the same requirement. Hence it is not possible for > 2 bytes to cross a page boundary. Hmm, that's an interesting chain of reasoning. I see no fault in it, so we just need to make sure we google it out when someone other than usb-storage somehow manages to submit a tricky buffer and crashes usbmon... I'm saving it locally too. -- Pete -- 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
