How do "new" and "delete" work without OS?

[Chen Bill-R63518 <R63518@xxxxxxxxxxxxx>]

Dear all,
I am using arm-none-elf-g++ to compile cpp files. Then I will use arm-none-elf-ld link the objects with libstdc++.a. The output codes will run without any OS. And in the c++ source code some "new" and "delete" operations are called, ie. there are some dynamic memory allocation.

Here are my questions:
How do the operator "new" and "delete" in the c++ lib work to manage the memory without OS? Should I override the "new" and "delete" operator myself to implement dynamic memory allocation?

Thanks and best regards!
Bill