On Fri, Dec 12, 2008 at 12:17:58PM -0600, Anthony Liguori wrote: > You assume that anything using bdrv_aio_readv/writev will be going through > a DMA API. This isn't a safe assumption.
Well it's obviously a safe assumption right now... ;) I've an hard time seeing any 'metadata' (because _data_ will be guaranteed to always pass through the dma api if it wants to be vectored) being physically contiguous on disk but not contiguous on ram. > Furthermore, you need some way to communicate the fact that you cannot > handle iovcnt > 1 iovecs in a performant/safe way. assert(iovcnt == 1) will work fine. If somebody changes some backend like qcow2 to call bdrv_aio_readv/writev they'll get an assert and they'll ask for a compatibility layer. I don't see any urgency to add it immediately and I think assert(iovcnt==1) is more preferable until any user emerges asking for bdrv_aio_readv/writev as it'll function as a debug trap to be sure all works right. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
