On Tue, Nov 17, 2015 at 02:07:58PM -0500, Alan Stern wrote: > If we really want to do zerocopy I/O then we should not use a bounce > buffer. But the only way to avoid bounce buffers may be to give user > programs a way of allocating memory pages below 4 GB, because lots of > USB hardware can only do 32-bit DMA.
But any system worth it's money these days has an IOMMU. > Is there an API for allocating user memory below 4 GB? Would a new > MMAP flag be acceptable? You'll have to ask the MM folks. But I doubt they will be excited about it. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
