https://csci1670.github.io/docs/project4/Recent content in Project 4: Privilege Separation and System Calls on CS 1670: Operating SystemsHugoen-ushttps://csci1670.github.io/docs/project4/debug/Mon, 01 Jan 0001 00:00:00 +0000https://csci1670.github.io/docs/project4/debug/<style> section { margin-bottom: 2rem; padding: 0em 1em; padding-bottom: 1em; border-radius: 4px; background-color: #f7f7f7; border: 1px solid #ccc; } center { text-align: center; } summary { font-weight: bolder; } summary:hover { text-decoration: underline } </style> <h1 id="appendix-a-debugging-the-userkernel-boundary"> Appendix A: Debugging the User/Kernel Boundary <a class="anchor" aria-hidden="true" href="#appendix-a-debugging-the-userkernel-boundary"></a> </h1> <p>Everything in the debugging appendices of <a href="https://csci1670.github.io/docs/project2/debug/">Project 2</a> and <a href="https://csci1670.github.io/docs/project3/debug/">Project 3</a> still applies, and so do the <code>CHECK()</code> and <code>DEBUG()</code> macros from <a href="https://csci1670.github.io/docs/project2/assertions/">Project 2&rsquo;s Appendix D</a>. This project adds one new category of wrong: <strong>the CPU is at a different exception level, or on a different stack, than you think.</strong> Most of the bugs in this project show up as an exception in an unexpected place, and almost all of them can be diagnosed from three numbers: the exception class in <code>ESR_EL1</code>, the address in <code>ELR_EL1</code>, and the mode bits of the saved <code>SPSR_EL1</code>.</p>