--- title: Mainline Explicit Fencing | daily.dev description: An overview of the Android Sync Framework, the first out-of-tree explicit fencing implementation for the Linux Kernel. Covers the core primitives: Sync... canonical: https://daily.dev/posts/mainline-explicit-fencing-v3ytcpgmc twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Mainline Explicit Fencing | daily.dev og:description: An overview of the Android Sync Framework, the first out-of-tree explicit fencing implementation for the Linux Kernel. Covers the core primitives: Sync... og:url: https://daily.dev/posts/mainline-explicit-fencing-v3ytcpgmc og:image: https://api.daily.dev/og/posts/V3YtcpGmc.png og:image:alt: Mainline Explicit Fencing og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Mainline Explicit Fencing **[Collabora Blog](https://daily.dev/sources/collabora)** · 3 min read · 0 upvotes · 0 comments ## Summary An overview of the Android Sync Framework, the first out-of-tree explicit fencing implementation for the Linux Kernel. Covers the core primitives: Sync Timelines (monotonically increasing counters per driver context), Sync Points (fences tied to specific timeline values), and Sync Fences (file-descriptor-backed structs for passing sync information between kernel and userspace). Also explains fence merging — combining multiple Sync Fences into one that signals only when all contained Sync Points signal — and the three ioctl calls exposed to userspace for waiting, merging, and inspecting fences. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How does the Android Sync Framework implement explicit fencing in the Linux kernel? The Android Sync Framework uses three primitives: a Sync Timeline (a per-driver monotonically increasing counter), Sync Points (fences tied to a specific timeline value that transition from Active to Signaled when a job completes), and Sync Fences (Linux file structs associated with a file descriptor for passing sync info between kernel and userspace). Multiple Sync Fences can be merged into one that signals only when all contained Sync Points signal. _Kernel and graphics driver developers tracking explicit fencing developments share findings on daily.dev._ ### What ioctl calls does the Android Sync Framework expose to userspace? The Android Sync Framework exposes three ioctl calls: one to wait on a sync_fence to signal, one to merge two sync_fences into a new third sync_fence, and one to retrieve information about a sync_fence and all its sync_points. Sync fence file descriptors are passed to and from the kernel in calls to request buffer rendering or display. _Engineers working with GPU or display driver APIs find relevant kernel synchronization discussions on daily.dev._ ## Similar posts on daily.dev - [Qualcomm Proposes Synx For The Linux Kernel With "Significant" Power \+ Performance Benefits](https://daily.dev/posts/qualcomm-proposes-synx-for-the-linux-kernel-with-significant-power-performance-benefits-zeafm5e2v) · Phoronix · 0 upvotes · 0 comments - [Linux gaming is getting faster because Windows APIs are becoming Linux kernel features](https://daily.dev/posts/linux-gaming-is-getting-faster-because-windows-apis-are-becoming-linux-kernel-features-hwutw21m3) · XDA Developers · 1 upvotes · 0 comments - [Investigating Linux graphics](https://daily.dev/posts/investigating-linux-graphics-pt8vvc5hu) · Lobsters · 0 upvotes · 0 comments - [The Async Multiprocessing Has Sound Foundations in Linux, But Further Testing Is Needed](https://daily.dev/posts/the-async-multiprocessing-has-sound-foundations-in-linux-but-further-testing-is-needed-lpf8czcgo) · InfoQ · 0 upvotes · 0 comments --- Tags: [#linux](https://daily.dev/tags/linux) [View this post on daily.dev](https://daily.dev/posts/mainline-explicit-fencing-v3ytcpgmc) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Mainline Explicit Fencing","url":"https://daily.dev/posts/mainline-explicit-fencing-v3ytcpgmc","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/mainline-explicit-fencing-v3ytcpgmc"},"datePublished":"2026-08-11T08:57:00.551Z","dateModified":"2026-08-11T09:36:09.142Z","description":"An overview of the Android Sync Framework, the first out-of-tree explicit fencing implementation for the Linux Kernel. 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