\documentclass{article}
\input{6828-preamble}

\begin{document}
\psetnum{22}
\date{2004/11/29}

\begin{pset}
  \begin{problem}
    User processes would be able to access locations in physical
    memory without regard for page permissions via the
    \texttt{sys\_cputs} and \texttt{sys\_cgetc} syscalls if we did not
    use the \texttt{TRUP} macro.
  \end{problem}

  \begin{problem}
    We can achieve this goal by executing the calculator program in
    some sort of restricted-capability environment. In an exokernel
    system like JOS, the capability that would need to be restricted
    would generally be the capability to send IPC messages to other
    processes. So we would require a way for a parent process to place
    restrictions on which processes a child process can communicate
    with via IPC.
  \end{problem}
\end{pset}

\end{document}
