> I remember the mill architecture[1] also claims to have that capability, I think they called these calls "Portals".
The Mill's "Portals" are more intended for inter-process calls than for compartmentalisation within a process. The Mill can have fine-grained protection of memory temporarily given to a callee because protection ranges are separate from paging. I believe there have been several research OS:es that did pass full pages back and forth over IPC, but at the cost of setting these up and restricting them to that purpose.
Because Portals are so cheap they could probably be useful for compartmentalising larger complex applications such as a modern-day web browser into smaller chunks than today.
BTW, Goddard has told that the Mill team once considered a capability-oriented architecture but they chose not to because the model they had in mind broke C's pointer semantics in some way. They have chosen to prioritise compliance with the C spec, so as to be able to market the architecture.
The Mill's "Portals" are more intended for inter-process calls than for compartmentalisation within a process. The Mill can have fine-grained protection of memory temporarily given to a callee because protection ranges are separate from paging. I believe there have been several research OS:es that did pass full pages back and forth over IPC, but at the cost of setting these up and restricting them to that purpose.
Because Portals are so cheap they could probably be useful for compartmentalising larger complex applications such as a modern-day web browser into smaller chunks than today.
BTW, Goddard has told that the Mill team once considered a capability-oriented architecture but they chose not to because the model they had in mind broke C's pointer semantics in some way. They have chosen to prioritise compliance with the C spec, so as to be able to market the architecture.