On Thu, May 07, 2015 at 10:47:15AM +0200, David Borman wrote: > I just want to introduce myseld. Iam David from Germany and hope i can ask > some development specific questions and this is the right place.What is my > best starting point getting familar with the networking code and is there > any useful, technicall documentation out there? > > Iam espacially interrested in how QEMU handles/routes the incoming > networktraffic (from reaching physically the hosts ethernetc card, forwarded > into quemu networking and delegation to one of the running Guests OS > Instances.
That is largely not done in the QEMU codebase. Many users rely on the -netdev tap option and use the host kernel's network stack for bridging or NAT. There is a userspace NAT solution (hack?) in QEMU which parses TCP/UDP packets and performs equivalent socket system calls. This is useful when running QEMU without permissions for the tun/tap device driver. But it's not how most users do networking on production VMs. Also, the vhost_net.ko driver on Linux bypasses QEMU and performs virtio-net rx/tx in the host kernel. So from that perspective, you may need to study the Linux source code and poke at a live host where libvirt has set up networking for VMs to understand how things work together. Stefan
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