According to embodiments of the invention, methods, computer system, and apparatus for virtual channel management and bus multiplexing are disclosed. The method may include establishing a virtual channel from a first device to a second device via a bus, the bus having a first bus capacity and a second bus capacity, the second bus capacity having greater capacity than the first bus capacity, determining whether a store command is issued for the first bus capacity, determining whether the first bus capacity is available, and allocating the second bus capacity and marking the second bus capacity as unavailable in response to the store command if the first bus capacity is unavailable.