System service calls

OK, so now I am working on the ability of controls written in VHDL to access services from "parent" controls. This is what will pass for a generic system call type interface. Here goes: Each control which wants to make use of a parent control's services will need to port itself into a system-wide ethernet bus and then make a DHCP request, which will provide an IP address within a subnet managed by the parent control. A messaging port on a gateway managed by the parent control will allow the child control(s) to communicate service requests to the parent, or even route the service requests further upstream to a parent network for handling, depending on the type of service requested.

As an example of this, the initial parent-child relationship to be designed and tested will be a simple console-print service, wherein a listener process will accept TCP request packets on a specific port to specify a string to output on the system console. Further types of services to be developed will include hierarchical process scheduling, interprocess communication, memory allocation, access to low-level device interfaces, and in general any other type of resource-allocation task you might find in a typical operating system.

All of this will require a native interface to network services such as TUN/TAP (for running a local net in userspace), DHCP (for allocating subnets), iptables (for managing NAT between the subnets), etc etc. Of course, most of this code will need to be replaced with VHDL equivalents at some point in order to be able to synthesize a "real" circuit with all of these capabilities, but for now it is a relief to be able to wrap the above-mentioned features with VHPI and get on with the rest of the Controlix design.