Console over Ethernet

While console support is one of the most mundane portions of an operating system, console access is critical, especially during system debugging and for some low-level system-administration operations. As a result, densely packed servers and server appliances have either keyboard/video/mouse (KVM) cabling and KVM switches or serial ports, cabling, and concentrators. Further increases in the density of server appliances and blades require eliminating these items. We did so in the design of a prototype dense-server-blade system that includes none of the standard external ports for console devices. Since the standard means for console accesss, KVM or serial, were not possible, we developed low-level software to redirect console activity to the Ethernet interface. This paper describes the console support over the network interface that we developed for both our LinuxBIOS-based boot-time firmware and the Linux operating system. We refer to this code as console over Ethernet or etherconsole. We found it invaluable in debugging and evaluating our prototype server blades. We also describe ways of extending our work to make it more transparent to existing firmware and operating systems.