* [utest/mm] add testcase for create/init
format codes of create/init in components/mm
* [libcpu/aarch64] fix user stack check routine
* [kservice] export API for utest
* [utest/mm] testcase for aspace_map
format & modify the files under components/mm related with aspace_map
* [lwp/user_mm] add user_map_varea for mmap feature
* [mm] rename rt_mm_fault_try_fix to rt_aspace_fault_try_fix
* [utest/mm] testcase for synchronization
* [mm] modify unmap api to improve throughput
* [utest/mm] testcases for cache and varea map
* [format] remove extra space
* [utest/mm] fix testcase problem in header
* [lwp] extend map_user_varea with a flag
* [utest/mm] testcase for lwp_map_user_varea
* [libcpu/arm/cortex-a] fix kernel space layout
* [utest/mm] adjust for armv7 arch
* [mm] mmu operations should be wrapped by _aspace_bst_insert & _aspace_bst_remove to avoid competition on page table
* [lwp] may not return null on failed
* Synchronize the code of the rt mart branch to the master branch.
* TTY device
* Add lwP code from rt-smart
* Add vnode in DFS, but DFS will be re-write for rt-smart
* There are three libcpu for rt-smart:
* arm/cortex-a, arm/aarch64
* riscv64
Co-authored-by: Rbb666 <zhangbingru@rt-thread.com>
Co-authored-by: zhkag <zhkag@foxmail.com>
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