<!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=UTF-8" 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">
<div style="color: #333333; border-bottom-width: 8px; border-bottom-color: #ededed; border-bottom-style: solid; font-weight: bold; line-height: 1.4; padding: 20px 0;">
Merge request <a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/1193">!1193</a> was reviewed by <a href="https://gitlab.rtems.org/wmthornton-dev">Wayne Thornton</a>
</div>
<p style="color: #777777;">
<a href="https://gitlab.rtems.org/wmthornton-dev">Wayne Thornton</a>
commented on a
discussion on <a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/1193#note_150423">cpukit/include/rtems/dhrl.h</a>:
</p>
<table class="code gl-mb-5" style="border-spacing: 0; margin-bottom: 1rem; border-collapse: collapse; width: auto; font-family: monospace; font-size: 90%;" bgcolor="#ffffff" width="100%" cellpadding="0" cellspacing="0">
<tr class="line_holder new" style="line-height: 1.6;">
<td class="old_line diff-line-num new" data-linenumber="1" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
</td>
<td class="new_line diff-line-num new" data-linenumber="6" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
6
</td>
<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style="display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;">+<span class="line" data-lang="c"><span class="cm" style="color: #999988; font-style: italic;"> * @brief Deterministic Hedged Read Library (DHRL) Public API</span></span>
</pre></td>
</tr>
<tr class="line_holder new" style="line-height: 1.6;">
<td class="old_line diff-line-num new" data-linenumber="1" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
</td>
<td class="new_line diff-line-num new" data-linenumber="7" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
7
</td>
<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style="display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;">+<span class="line" data-lang="c"><span class="cm" style="color: #999988; font-style: italic;"> *</span></span>
</pre></td>
</tr>
<tr class="line_holder new" style="line-height: 1.6;">
<td class="old_line diff-line-num new" data-linenumber="1" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
</td>
<td class="new_line diff-line-num new" data-linenumber="8" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
8
</td>
<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style="display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;">+<span class="line" data-lang="c"><span class="cm" style="color: #999988; font-style: italic;"> * @note This library is explicitly constrained to x86_64/amd64 architectures.</span></span>
</pre></td>
</tr>
</table>
<div class="md" style="border-bottom-width: 4px; border-bottom-color: #ededed; border-bottom-style: solid; padding-bottom: 1em; position: relative; z-index: 1; color: #3a383f; word-wrap: break-word;">
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">Hi <a href="https://gitlab.rtems.org/gedare" title="Gedare Bloom" class="gfm gfm-project_member js-user-link" data-user="8" data-original="@gedare" data-container="body" data-placement="top" data-reference-type="user" style="color: #284779; background-color: #cbe2f9; border-radius: .25rem; margin-top: 0; padding: 0 2px;">@gedare</a>, thanks for the review.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">You are correct, the current limitation is due to the inline assembly required for cache invalidation (clflush) and cycle timing (pause/rdtsc), which are currently hardcoded.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">I agree that this shouldn't bottleneck the cpukit level. I will refactor the implementation to abstract those hardware-specific instructions behind architecture hooks in score/cpu/, keeping the core API clean.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">However, I do want to flag a broader architectural concern. While the API will be portable, the actual efficacy of DHRL relies heavily on strict SMP core affinity and predictable memory controller behavior. On architectures with weakly ordered memory models or non-deterministic bus arbitration, a functional port might not be physically viable at the hardware level.</p>
<p dir="auto" style="color: #3a383f; margin: 0;" align="initial">My plan is to define the hooks so that unsupported architectures can safely stub them out and return RTEMS_UNSATISFIED (or simply compile to a no-op fallback) to prevent unexpected hardware behavior on non-x86 targets. Thoughts?</p>
</div>
</div>
<div class="footer" style="margin-top: 10px;">
<p style="font-size: small; color: #626168;">
—
<br>
<a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/1193">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/3-5l906q4uu02do4cxh25bs7x5y/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>
<span style="color: transparent; font-size: 0; display: none; overflow: hidden; opacity: 0; width: 0; height: 0; max-width: 0; max-height: 0;">
Notification message regarding https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/1193 at 1779109483
</span>
<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/1193"}}</script>
</p>
</div>
</body>
</html>