It seems that the api vm.get__totalmem_sys() is just used in boot_check.py, and the all_memory testcase doesn't claim a constant value for the size of the memory using in the case, when the assertion about system memory and the parameter memory is used, this case must fail.
Maybe I need the reference for vm object array to decide how to make the assertion works for all these memory cases.
Despite this, lgtm.

RFR