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<a href="https://gitlab.rtems.org/joel">Joel Sherrill</a> created an issue: <a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/issues/5558">#5558</a>
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<h2 id="user-content-summary" dir="auto" style="margin-top: 0; margin-bottom: 10px;" align="initial">Summary<a href="#summary" aria-label="Link to heading 'Summary'" data-heading-content="Summary" class="anchor" style="margin-top: 0;"></a>
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<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">A baud rate of 0 is valid per POSIX <a href="https://pubs.opengroup.org/onlinepubs/009696799/functions/tcsetattr.html" rel="nofollow noreferrer noopener" target="_blank" style="margin-top: 0;">tcsetattr()</a>. B0 is very old school UNIX and setting the baud rate to that indicates that the "the modem control lines shall no longer be asserted. Normally, this shall disconnect the line."</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">AFAIK no RTEMS UART drivers have support for modem control lines. If one did, it would have to explicitly check for B0.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">All uart/console drivers should have their set attributes function checked to ensure baud rate of 0 results in an error being returned rather than a divide by 0.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">I got caught by this while trying out <a href="https://flightsoftware.jhuapl.edu/files/_site/workshops/old_archive/2014/" rel="nofollow noreferrer noopener" target="_blank" style="margin-top: 0;">CodeSonar on RTEMS</a>. It was flagged as a missed divide by zero but is actually a feature not supported by the driver.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">See <a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/1216" title="bsp/arm/tms570: protect against baud rate divide-by-zero" class="gfm gfm-merge_request" data-original="MR 1216" data-link="true" data-link-reference="true" data-merge-request="2540" data-project="26" data-project-path="rtems/rtos/rtems" data-iid="1216" data-container="body" data-placement="top" data-reference-type="merge_request" style="margin-top: 0;">MR 1216</a> for one case of this being addressed.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">See <a href="https://gitlab.rtems.org/rtems/docs/rtems-docs/-/issues/144" title="BSP Guide 6.8 Console Set Attributes Should Discuss B0" class="gfm gfm-issue" data-original="this" data-link="true" data-link-reference="true" data-issue="29638" data-project="12" data-iid="144" data-namespace-path="rtems/docs/rtems-docs" data-project-path="rtems/docs/rtems-docs" data-issue-type="issue" data-container="body" data-placement="top" data-reference-type="issue" style="margin-top: 0;">this</a> documentation issue for updating to discuss this.</p>
<h2 id="user-content-steps-to-reproduce" dir="auto" style="margin-top: 20px; margin-bottom: 10px;" align="initial">Steps to reproduce<a href="#steps-to-reproduce" aria-label="Link to heading 'Steps to reproduce'" data-heading-content="Steps to reproduce" class="anchor" style="margin-top: 0;"></a>
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<p dir="auto" style="color: #3a383f; margin: 0;" align="initial">Code review.</p>
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