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Innovations and Strengthening Platforms Reliability Through Open Source

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KashanK
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Nov 18, 2025

Microsoft’s Open-Source Contributions for Platforms Reliability and Performance.

The Linux Systems Group (LSG) at Microsoft is the team building OS innovations in Azure enabling secure and high-performance platforms that power millions of workloads worldwide. From providing the OS for Boost, optimizing Linux kernels for hyperscale environments or contributing to open-source projects like Rust-VMM and Cloud Hypervisor, LSG ensures customers get the best of Linux on Azure. Our work spans performance tuning, security hardening, and feature enablement for new silicon enablement and cutting-edge technologies, such as Confidential Computing, ARM64 and Nvidia Grace Blackwell all while strengthening the global open-source ecosystem. Our philosophy is simple: we develop in the open and upstream first, integrating improvements into our products after they’ve been accepted by the community.

At Ignite we like to highlight a few open-source key contributions in 2025 that are the foundations for many product offerings and innovations you will see during the whole week. We helped bring seamless kernel update features (Kexec HandOver) to the Linux kernel, improved networking paths for AI platforms, strengthened container orchestration and security efforts, and shared engineering insights with global communities and conferences. This work reflects Microsoft’s long-standing commitment to open source, grounded in active upstream participation and close collaboration with partners across the ecosystem. Our engineers work side-by-side with maintainers, Linux distro partners, and silicon providers to ensure contributions land where they help the most, from kernel updates to improvements that support new silicon platforms.

Linux Kernel Contributions

Enabling Seamless Kernel Updates: Persistent uptime for critical services is a top priority. This year, Microsoft engineer Mike Rapoport successfully merged Kexec HandOver (KHO) into Linux 6.16 1 . KHO is a kernel mechanism that preserves memory state across a reboot (kexec), allowing systems to carry over important data when loading a new kernel. In practice, this means Microsoft can apply security patches or kernel updates to Azure platform and customers VMs without rebooting or with significantly reduced downtime. It’s a technical achievement with real impact: cloud providers and enterprises can update Linux on the fly, enhancing security and reliability for services that demand continuous availability.

Optimizing Network Drivers for AI Scale: Massive AI models require massive bandwidth. Working closely with our partners deploying large AI workloads on Azure, LSG engineers delivered a breakthrough in Linux networking performance. LSG team rearchitected the receive path of the MANA network driver (used by our smart NICs) to eliminate wasted memory and enable recycling of buffers.

  • 2x higher effective network throughput on 64 KB page systems
  • 35% better memory efficiency for RX buffers
  • 15% higher throughput and roughly half the memory use even on standard x86_64 VMs

References

Improving Reliability for Cloud Networking: In addition to raw performance, reliability got a boost. One critical fix addressed a race condition in the Hyper-V hv_netvsc driver that sometimes caused packet loss when a VM’s network channel initialized. By patching this upstream, we improved network stability for all Linux guests running on Hyper-V keeping customer VMs running smoothly during dynamic operations like scale-out or live migrations. Our engineers also upstreamed numerous improvements to Hyper-V device drivers (covering storage, memory, and general virtualization).We fixed interrupt handling bugs, eliminated outdated patches, and resolved issues affecting ARM64 architectures. Each of these fixes was contributed to the mainline kernel, ensuring that any Linux distribution running on Hyper-V or Azure benefits from the enhanced stability and performance.

References

  • Upstream fix: hv_netvsc race on early receive events: kernel.org commit referenced by Ubuntu bug Launchpad
  • Ubuntu Azure backport write-up: Bug 2127705 – hv_netvsc: fix loss of early receive events from host during channel open Launchpad
  • Older background on hv_netvsc packet-loss issues: kernel.org bug 81061

Strengthening Core Linux Infrastructure: Several of our contributions targeted fundamental kernel subsystems that all Linux users rely on. For example, we  led significant enhancements to the Virtual File System (VFS) layer  reworking how Linux handles process core dumps and expanding file management capabilities. These changes improve how Linux handles files and memory under the hood, benefiting scenarios from large-scale cloud storage to local development. We also continued upstream efforts to support advanced virtualization features.Our team is actively upstreaming the mshv_vtl driver (for managing secure partitions on Hyper-V) and improving Linux’s compatibility with nested virtualization on Azure’s Microsoft Hypervisor (MSHV). All this low-level work adds up to a more robust and feature-rich kernel for everyone.

References

 Bolstering Linux Security in the Cloud: Security has been a major thread across our upstream contributions. One focus area is making container workloads easier to verify and control. Microsoft engineers proposed an approach for code integrity in containers built on containerd’s EROFS snapshotter, shared as an open RFC in the containerd project -GitHub. The idea is to use read-only images plus integrity metadata so that container file systems can be measured and checked against policy before they run.

We also engaged deeply with industry partners on kernel vulnerability handling. Through the Cloud-LTS Linux CVE workgroup, cloud providers and vendors collaborate in the open on a shared analysis of Linux CVEs. The group maintains a public repository that records how each CVE affects various kernels and configurations, which helps reduce duplicated triage work and speeds up security responses.

On the platform side, our engineers contributed fixes to the OP-TEE secure OS used in trusted execution and secure-boot scenarios, making sure that the cryptographic primitives required by Azure’s Linux boot flows behave correctly across supported devices. These changes help ensure that Linux verified boot chains remain reliable on Azure hardware.

References

Developer Tools & Experience

Smoother OS Management with Systemd: Ensuring Linux works seamlessly on Azure scale. The core init system systemd saw important improvements from our team this year. LSG contributed and merged upstream support for disk quota controls in systemd services. With new directives (like StateDirectoryQuota and CacheDirectoryQuota), administrators can easily enforce storage limits for service data, which is especially useful in scenarios like IoT devices with eMMC storage on Azure’s custom SoCs. In addition, Sea-Team added an auto-reload feature to systemd-journald, allowing log configuration changes to apply at runtime without restarting the logging service . These improvements, now part of upstream systemd, help Azure and other Linux environments perform updates or maintenance with minimal disruption to running services. These improvements help Azure and other environments roll out configuration updates with less impact on running workloads.

References

 Empowering Linux Quality at Scale: Running Linux on Azure at global scale requires extensive, repeatable testing. Microsoft continues to invest in LISA (Linux Integration Services Automation), an open-source framework that validates Linux kernels and distributions on Azure and other Hyper-V–based environments.

Over the past year we expanded LISA with:

  • New stress tests for rapid reboot sequences to catch elusive timing bugs
  • Better failure diagnostics to make complex issues easier to root-cause
  • Extended coverage for ARM64 scenarios and technologies like InfiniBand networking
  • Integration of Azure VM SKU metadata and policy checks so that image validation can automatically confirm conformance to Azure requirements

These changes help us qualify new kernels, distributions, and VM SKUs before they are shipped to customers. Because LISA is open source, partners and Linux vendors can run the same tests and share results, which raises quality across the ecosystem.

References

Community Engagement and Leadership

Sharing Knowledge Globally: Open-source contribution is not just about code - it’s about people and knowledge exchange. Our team members took active roles in community events worldwide, reflecting Microsoft’s growing leadership in the Linux community. We were proud to be a Platinum Sponsor of the inaugural Open Source Summit India 2025 in Hyderabad, where LSG engineers served on the program committee and hosted technical sessions. At Linux Security Summit Europe 2025, Microsoft’s security experts shaped the agenda as program committee members, delivered talks (such as “The State of SELinux”), and even led panel discussions alongside colleagues from Intel, Arm, and others. And in Paris at Kernel Recipes 2025, our own SMEs shared kernel insights with fellow developers. By engaging in these events, Microsoft not only contributes code but also helps guide the conversation on the future of Linux. These relationships and public interactions build mutual trust and ensure that we remain closely aligned with community priorities.

References

Closing Thoughts

Microsoft’s long-term commitment to open source remains strong, and the Linux Systems Group will continue contributing upstream, collaborating across the industry, and supporting the upstream communities that shape the technologies we rely on. Our work begins in upstream projects such as the Linux kernel, Kubernetes, and systemd, where improvements are shared openly before they reach Azure. The progress highlighted in this blog was made possible by the wider Linux community whose feedback, reviews, and shared ideas help refine every contribution. As we move ahead, we welcome maintainers, developers, and enterprise teams to engage with our projects, offer input, and collaborate with us. We will continue contributing code, sharing knowledge, and supporting the open-source technologies that power modern computing, working with the community to strengthen the foundation and shape a future that benefits everyone.

References & Resources:

Updated Nov 18, 2025
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