Am Mittwoch, 7. April 2010 16:59:47 schrieb Alan Stern: > > The fix is to use usb_buffer_alloc() for that purpose which ensures > > memory that is suitable for DMA. And on x86_64, this also means that the > > upper 32 bits of the address returned are all 0's. > > That is not a good fix. usb_buffer_alloc() provides coherent memory, > which is not what we want. I believe the correct fix is to specify the > GFP_DMA32 flag in the kzalloc() call. > > Of course, some EHCI hardware is capable of using 64-bit addresses. > But not all, and other controller types aren't. In principle we could > create a new allocation routine, which would take a pointer to the USB > bus as an additional argument and use it to decide whether the memory > needs to lie below 4 GB. I'm not sure adding this extra complexity > would be worthwhile. What about XHCI? Do you really want to limit it to 32bits? Regards Oliver -- 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
