* initial virtual memory;

* initial integration;

* include the header file in cmake;

* implement allocation with virtual to logical address mapping;

* virtual memory for tsim_driver;

* implement the missing memory release function;

* readability improvement;

* readability improvement;

* address review comments;

* improved robustness in virtual memory allocation;

* remove VTA_TSIM_USE_VIRTUAL_MEMORY macro and use virtual memory for tsim by default;

* link tvm against vta library;

* merge with master

* build virtual memory system without linking tvm against vta;

* minor change;

* reuse VTA_PAGE_BYTES;

* using DRAM class from sim_driver as VirtualMemoryManager;

* satisfy linter;

* add comments in code;

* undo changes to Makefile

* undo changes to Makefile

* retrigger ci;

* retrigger ci;

* directly call into VirtualMemoryManager::Global()