<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html lang="en" style='--code-editor-font: var(--default-mono-font, "GitLab Mono"), JetBrains Mono, Menlo, DejaVu Sans Mono, Liberation Mono, Consolas, Ubuntu Mono, Courier New, andale mono, lucida console, monospace;'>
<head>
<meta content="text/html; charset=US-ASCII" http-equiv="Content-Type">
<title>
GitLab
</title>
<style data-premailer="ignore" type="text/css">
a { color: #1068bf; }
</style>
<style>img {
max-width: 100%; height: auto;
}
body {
font-size: .875rem;
}
body {
-webkit-text-shadow: rgba(255,255,255,.01) 0 0 1px;
}
body {
font-family: "GitLab Sans",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Noto Sans",Ubuntu,Cantarell,"Helvetica Neue",sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol","Noto Color Emoji"; font-size: inherit;
}
</style>
</head>
<body style='font-size: inherit; -webkit-text-shadow: rgba(255,255,255,.01) 0 0 1px; font-family: "GitLab Sans",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Noto Sans",Ubuntu,Cantarell,"Helvetica Neue",sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol","Noto Color Emoji";'>
<div class="content">
<p class="details" style="font-style: italic; color: #737278;">
<a href="https://gitlab.rtems.org/matteo.concas">Matteo Concas</a> created a merge request: <a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/538">!538</a>
</p>
<div class="branch">
Project:Branches: matteo.concas/rtems-gaisler:matteo/add-Smdbltrp-compat to rtems/rtos/rtems:main
</div>
<div class="author">
Author: Matteo Concas
</div>
<div class="assignee">
Assignees:
</div>
<div class="reviewer">
Reviewers:
</div>
<div class="approvers">
</div>
<div class="md gl-mt-5" style="position: relative; z-index: 1; color: #28272d; word-wrap: break-word; margin-top: 1rem;">
<h2 dir="auto" style="font-size: 1.5em; font-weight: 600; padding-bottom: .3em; border-bottom-width: 1px; border-bottom-color: #bfbfc3; border-bottom-style: solid; color: #28272d; margin: 0 0 16px;" align="initial">
<a href="#summary" aria-hidden="true" class="anchor" id="user-content-summary" style="margin-top: 0; float: left; margin-left: -20px; text-decoration: none; outline: none;"></a>Summary</h2>
<p dir="auto" style="color: #28272d; margin: 0 0 16px;" align="initial">cpu/riscv: Add Smdbltrp extension compatibility</p>
<p dir="auto" style="color: #28272d; margin: 0 0 16px;" align="initial">If the Double Trap Extension is implemented, the MDT bit of the mstatus (or mstatush in RV32) register will be set when a trap is to be taken.</p>
<p dir="auto" style="color: #28272d; margin: 0 0 16px;" align="initial">The MIE (Machine Interrupt Enable) bit can only be set to 1 if the MDT bit is zero.</p>
<p dir="auto" style="color: #28272d; margin: 0 0 16px;" align="initial">Thus, we need to clear MDT first if we want to enable interrupts when dispatching a thread.</p>
<p dir="auto" style="color: #28272d; margin: 0 0 16px;" align="initial">MDT is also cleared in register <code style='font-size: 90%; color: #18171d; word-wrap: break-word; background-color: #ececef; border-radius: .25rem; margin-top: 0; font-weight: inherit; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; vertical-align: bottom; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 2px 4px;'>a1</code> before restoring the interrupt frame as writing 1 to MDT will cause MIE to be set to 0. In RV64 this happens regardless of the value written to MIE in the same write.</p>
<p dir="auto" style="color: #28272d; margin: 0 0 16px;" align="initial">In RV32, MDT is in mstatush so we do not need to clear during restore as this register is not restored.</p>
<p dir="auto" style="color: #28272d; margin: 0 0 16px;" align="initial">With this change all 60 SMP tests pass (compared to 20/60 before the fix). The tests have been run on hardware using two RV64 CPUs that implement the double trap extension.</p>
<p dir="auto" style="color: #28272d; margin: 0;" align="initial">Update <a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/issues/5274" data-reference-type="issue" data-original="#5274" data-link="false" data-link-reference="false" data-issue="29104" data-project="26" data-iid="5274" data-namespace-path="rtems/rtos/rtems" data-project-path="rtems/rtos/rtems" data-issue-type="issue" data-container="body" data-placement="top" title="RISC-V implementation does not support Smdbltrp extension" class="gfm gfm-issue" style="margin-top: 0;">#5274</a></p>
</div>
</div>
<div class="footer" style="margin-top: 10px;">
<p style="font-size: small; color: #737278;">
—
<br>
<a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/538">View it on GitLab</a>.
<br>
You're receiving this email because of your account on <a target="_blank" rel="noopener noreferrer" href="https://gitlab.rtems.org">gitlab.rtems.org</a>. <a href="https://gitlab.rtems.org/-/sent_notifications/6b3e5c8f3ed7fec30c37cfa2039e3417/unsubscribe" target="_blank" rel="noopener noreferrer">Unsubscribe</a> from this thread · <a href="https://gitlab.rtems.org/-/profile/notifications" target="_blank" rel="noopener noreferrer" class="mng-notif-link">Manage all notifications</a> · <a href="https://gitlab.rtems.org/help" target="_blank" rel="noopener noreferrer" class="help-link">Help</a>
<script type="application/ld+json">{"@context":"http://schema.org","@type":"EmailMessage","action":{"@type":"ViewAction","name":"View Merge request","url":"https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/538"}}</script>
</p>
</div>
</body>
</html>