Question about OS calls in RISCV BSP

Hi,

I'm the confused about the list of functions to be implemented in a BSP.
Newlib documentation explains 19 syscalls listed here is the "complete set
of system definitions <https://sourceware.org/newlib/libc.html#Syscalls>".
But when I look at RISC-V BSP
<https://github.com/riscv/riscv-newlib/tree/riscv-newlib-3.1.0/libgloss/riscv>,
I see lot more extra routines implemented such as getcwd, chown, chdir etc.
What is the exact list of subroutines a BSP has to implement?

Also, any reason why is fcntl missing in the Newlib documentation's list?
It seems one of the syscalls required by this list
<https://github.com/eblot/newlib/tree/master/newlib/libc/syscalls>.

Thanks you,
Bandhav