ForwardCom: Proposal for forward compatible instruction set architecture (2018)

> In current architectures VM is flat and continuous

Looking at /proc/$PID/maps for firefox, it contains well over 100 noncontiguous map ranges. The address 0x11b000000000, for example, is not mapped to anything, but addresses above and below it are.

You can handle the heap growing by just allocating a new page for it somewhere in free memory. Your heap doesn't have to be contiguous.

My understanding is that there's still VM, but it uses a separate buffer (on-chip memory map) containing a list of segments that map each part of the process' memory to a physical address (virt->physical offset + length), rather than a multi-tiered paging structure. The advantage is quick virtual -> physical address translation and less space used for them vs page tables, but the downside, as you point out, is what to do when a process exceeds it's initial heap or stack segment.

In this case, I think the Forwardcom solution is to add another entry in the memory map for the next 2*n bytes of heap space.