Ethernet upgrade

[Courtney3141]

This pull request is the result of concurrent work on different repositories over the course of 6-9 months.

The main updates include:

• Updates to the signalling protocol used by networking components to indicate to each other that processing is required on their ring buffers. The new protocol has been proved deadlock free using model checking verification software.
• Updates to the ring buffer data structure and enqueue/dequeue/init functions allowing ring buffers to take on different sizes depending on which protection domain they belong to, fixes to the ring buffer initialization process to avoid race conditions based on the order that protection domains are initializing, fixes to the enqueuing and dequeuing functions to avoid accessing stale ring buffer entries.
• Buffer descriptors now contain either offsets into the client's data region, or the physical address of the buffer. Never the virtual address.
• Various fixes to bugs in the preexisting code encountered during the development process.
• Optimisations to the ring buffer processing that the network components perform during their notified functions.
• Vastly improved documentation for the meson ethernet driver, as well as improvements to its performance and reliability (further work still needs to be done here).
• Unification of the printing mechanism for components. There is now one printf.h and printf.c. dprintf is also defined in printf.h allowing components to print only in debug mode. Depending on whether a component must print in release mode or only in debug, printf can be linked with a debug putchar utilising microkit_dbg_puts, or a serial putchar writing to the serial register directly. The serial putchar will instead notify the serial subsystem (serial mux_tx/uart driver) in future commits.
• Removal of unnecessary shared memory regions in the echo server system file which where only ever used as data for one protection domain.
• Reordering of clients channel numbers and memory regions so that the arp component is always the first client - since the arp component must always be a client, this reduces the number of changes required when decreasing or increasing the number of clients.
• The addition of an ethernet_config file which contains all the information that needs to be changed if a client is added or removed from the system, or configured differently (MAC address changed, ring buffer size changed, ...). This file is a temporary solution to the difficulties faced when altering a system file or network configuration, and is only intended to be used in the interim until an automatic header generator tool is created in the future.

[Ivan-Velickovic]

For VSpace cache operations, can you use the APIs:

• void microkit_arm_vspace_data_clean(uintptr_t start, uintptr_t end);
• void microkit_arm_vspace_data_invalidate(uintptr_t start, uintptr_t end);

I added them recently to the my fork of Microkit.

I will update the CI to use the latest Microkit SDK which should hopefully let the CI pass.

[Ivan-Velickovic]

Okay, added some fixes to get CI passing again.