On Mon, 2011-07-04 at 13:27 +0300, Avi Kivity wrote: > On 07/03/2011 08:44 PM, Sasha Levin wrote: > > On Sun, 2011-07-03 at 20:16 +0300, Avi Kivity wrote: > > > On 07/03/2011 08:04 PM, Sasha Levin wrote: > > > > > > > > - eventfd_signal(p->eventfd, 1); > > > > + if (p->pipe) > > > > + kernel_write(p->pipe, val, len, 0); > > > > > > You're writing potentially variable length data. > > > > > > We need a protocol containing address, data, length, and supporting read > > > accesses as well. > > > > > > > This can't be variable length. > > > > The user defines an ioeventfd as an address+length (with length being up > > to 8 bytes). The only time an ioeventfd is signaled is when the write to > > the guest memory is exactly at the specified address with exactly the > > specified length. > > > > It can be variable length if multiple ioeventfds reference the same pipe. > > > ioeventfds can be extended to handle more than 8 bytes, variable address > > offset and reads now that pipe support is added, but I'd rather do it in > > follow-up patches once basic pipe support is in. > > In general incremental development is great, but I don't want to > fragment the ABI. I'd like to be able to forward an entire PCI BAR over > a pipe. That means sending the address/data/length tuple, and both read > and write support. Would this mean that for sockets we want to remove the 8 byte limit? What about eventfds? We can remove the limit there and assume that if the user asked for more than 8 bytes he knows what he's doing? -- Sasha. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
