Hi all, I've been passively following seL4 for several years. I've been reading the documentation, tutorials, watching YouTube videos.
The concepts behind capabilities and other types of kernel objects are starting to sink in but there's one piece of understanding that's eluding me.
If I just haven't stumbled across it yet in the documentation, then pointing me in the right direction would be greatly appreciated.
Given:
* An ethernet driver named "e1000" and 2 devices "eth0" and "eth1" controlled by that driver.
* A "tcp" service that would implement that network protocol.
* A higher level service named "network" that implemented some kind of networking abstraction for us.
How would:
1) the "network" service advertise its services as available via IPC?
2) an application locate this "network" service to be able to IPC with it?
I assume the mechanisms here would also apply to interactions between services as well. I picked the "network" service in this example only because it would be the boundary between application and OS services.
I'm guessing that maybe this is purely an OS design decision and not the purvue of the kernel itself. Perhaps init could launch a "service manager" process that would be responsible for starting up services and drivers for example and this "service manager" could provide an IPC endpoint back to init (or whomever) to use for IPC discovery. Then, whenever a new process is started, it is provided with the IPC discovery endpoint information that it is to inherit.
If my assumptions are correct or close, or even dead wrong, would someone be willing to share some pseudo-code on what this could/should look like in seL4?
If a central service manager is needed to glue the core OS together, does it represent a single point of failure and how would the OS recover if it crashes and loses it's database of available services without having to rebuild and restart all drivers and services? (I'm not saying that's a bad thing, just trying to wrap my head around how this particular part of seL4 works)
Thanks,
Royce Mitchell, IT Consultant ITAS Solutions royce3@itas-solutions.com
There are three hard problems in computer science: naming things, and off-by-one errors.