Can I use a Single Linux OS to schedule two DSU cluster?

I'm not a kernel developer, but given what you've said I suspect it will be an uphill battle.  

Taking the GIC first, an OS is typically going to expect one GIC shared by all the cores running the same instance of the OS.  That's the assumption most standard drivers I've seen operate on.  I think you could work around it, but it could be quite complicated.  One example of why, in GIC an interrupt can only be Acknowledged by the core it is targeted to, but it can Deactivated from any core.  Things like threaded interrupt handlers make use of that property - but it won't work if the Ack'ing core and Deactivating core are connected to different GICs.  SW would have to know that was a possibility, test for it, and then deal with it in an SoC-specific way.

The memory system also sounds like it's going to be challenging.  If I've understood you correctly, most of the memory each core can see is not visible to the other cluster.  It's only a small portion of memory which is visible to both.  You could limit the allocator to just using the shared memory, but as it's only 1MB that's not very useful.  Using the non-shared memory is going to be a real challenge, as the kernel would need to know where the process was running to decide which memory to allocate.  Something like that can happen already, but that's usually for performance reasons not functional reasons.

I'm not a kernel developer, but given what you've said I suspect it will be an uphill battle.  

Taking the GIC first, an OS is typically going to expect one GIC shared by all the cores running the same instance of the OS.  That's the assumption most standard drivers I've seen operate on.  I think you could work around it, but it could be quite complicated.  One example of why, in GIC an interrupt can only be Acknowledged by the core it is targeted to, but it can Deactivated from any core.  Things like threaded interrupt handlers make use of that property - but it won't work if the Ack'ing core and Deactivating core are connected to different GICs.  SW would have to know that was a possibility, test for it, and then deal with it in an SoC-specific way.

The memory system also sounds like it's going to be challenging.  If I've understood you correctly, most of the memory each core can see is not visible to the other cluster.  It's only a small portion of memory which is visible to both.  You could limit the allocator to just using the shared memory, but as it's only 1MB that's not very useful.  Using the non-shared memory is going to be a real challenge, as the kernel would need to know where the process was running to decide which memory to allocate.  Something like that can happen already, but that's usually for performance reasons not functional reasons.