LoGin bcf46ccaea fix(tty): implement TCXONC flow control (#2225)
* fix(tty): implement TCXONC flow control

Implement the four TCXONC actions in N_TTY with job-control checks, committed termios snapshots, atomic output state transitions, and a driver xchar hook with a generic fallback.

Teach serial8250 to pause ordinary output while prioritizing flow-control characters, keep TX interrupt decisions consistent across console and IRQ paths, and reset private flow state across the first-open/last-close lifecycle. Preserve PTY packet notifications and gate virtual-terminal writes on the shared stopped state.

Add dunitest coverage for action validation, blocked-writer wakeups, custom and disabled control characters, output-postprocessing bypass, and idempotent PTY packet notifications.

Validation:
- make fmt
- make kernel
- tty_termios: 20/20 passed in DragonOS
- tty_tcflush: 6/6 passed in DragonOS
- tty_pty_hangup: 36/36 passed in DragonOS
- Python Ctrl+C produced KeyboardInterrupt without a kernel panic

Signed-off-by: longjin <longjin@dragonos.org>

* fix(tty): address flow-control races

Serialize the xchar fallback snapshot behind the TTY write lock and track external flow-control transitions. Restore a temporary stop only when no concurrent start or stop request superseded it, and issue deferred write readiness after dropping all re-entrant locks when a racing start observed the temporary running state.

Match Linux tty_port_close_start semantics for serial8250 by discarding a TCO-stopped software TX queue before waiting for already-submitted hardware bytes. This prevents last close from waiting for the fixed 30-second close timeout on a queue that cannot drain.

Add a DragonOS dunitest regression that queues serial output under TCOOFF and verifies last close completes promptly.

Validation:
- make fmt
- make kernel
- tty_termios: 21/21 passed in DragonOS
- tty_tcflush: 6/6 passed in DragonOS
- tty_pty_hangup: 36/36 passed in DragonOS
- Python Ctrl+C twice produced KeyboardInterrupt without a kernel panic

Signed-off-by: longjin <longjin@dragonos.org>

---------

Signed-off-by: longjin <longjin@dragonos.org>
2026-08-30 17:14:57 +08:00
2022-01-16 22:58:21 +08:00

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Lightweight Cloud-Native Kernel

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DragonOS

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DragonOS is a 64-bit operating system with a completely independent kernel, designed for lightweight cloud computing scenarios, offering Linux binary compatibility. It aims to provide lightweight, high-performance solutions for containerized workloads. Developed using Rust for enhanced reliability.

The DragonOS open-source community was established in July 2022 and is entirely commercially neutral. We warmly welcome interested developers and enthusiasts to join us!

DragonOS features excellent and comprehensive architectural design. Compared to other systems of similar scale, DragonOS supports eBPF and virtualization. Currently, we are actively advancing container support, cloud platform compatibility, RISC-V support, as well as porting compilers and application software. Our goal is to achieve large-scale production environment deployment within five years.

DragonOS is rapidly evolving under community-driven development. Currently, DragonOS has implemented approximately 1/4 of Linux interfaces. In the future, we will provide 100% Linux compatibility along with new features.

🌟 Want to quickly experience DragonOS? Visit DragonOS Playground to launch DragonOS in the cloud with zero configuration and experience the latest nightly build!

📰 Community News

  • 2025-12-17: ☁️ DragonOS Playground is now live! Experience DragonOS with zero configuration on CNB platform, with daily nightly build updates! Try it now →
  • 2025-11-20: 🚀 DragonOS 0.3.0 has been released! Now supports running Go programs directly!
  • 2025-11-18: 📊 DragonOS CI Dashboard is now live! Check out DragonOS Linux compatibility data now!

How to Run?

Zero configuration, one-click launch! Experience DragonOS on the CNB cloud-native development platform - the simplest and fastest way, no local dependencies required!

Launch on CNB

Method 2: Local Build

If you prefer to build and run DragonOS locally, you can refer to the following documentation:

Want to Contribute?

Read the DragonOS Community Introduction Document carefully to understand how the community operates and how you can contribute!

If you'd like to join us, check out the issues and participate in discussions or share your ideas. You can also visit the DragonOS forum to stay updated on development progress and tasks: https://bbs.dragonos.org.cn

You can also bring your creativity and ideas to discuss with the community and contribute new features to DragonOS.

Sites

How to Connect with the Community?

Please read the Contributor Guide~

  • You can find contact details for members of various committees in the Community Management Team section.
  • You can also locate the contact information for leaders of specific community groups via the SIGs and WGs pages.

Contributor List

Contributors to DragonOS-Community/DragonOS · GitHub

Sponsorship

Sponsor this project

DragonOS is a non-profit open-source project, and its development relies on financial support. All sponsors will be publicly acknowledged. Every contribution you make will help advance DragonOS!

Where Will Sponsorship Funds Be Used?

We guarantee that all sponsorship funds and items will be used for:

  • Event organization, cloud service expenses, and any other purposes beneficial to the development and growth of the DragonOS community.

🌟 Sponsor List

Special thanks to these generous financial supporters (in reverse chronological order):

CDN Sponsor

This project's CDN acceleration and security protection are sponsored by Tencent EdgeOne.

腾讯EdgeOne CDN

Individual Sponsors List

See Supporters.md

Open Source License Notice

This project is open-sourced under the GPLv2 license. You are welcome to use the code in compliance with the open-source license!

If you encounter any violations of the open-source license, we encourage you to email pmc@dragonos.org to report them. Let's work together to build a trustworthy open-source community.


👩💻 Contributors

"Open source shines because of you!"

Thanks to all developers who submitted code, fixed issues, or reviewed PRs:

S
Description
使用Rust从0自研内核,具有Linux兼容性的操作系统,面向云计算Serverless场景而设计。DragonOS is an operating system developed from scratch using Rust, with Linux compatibility. It is designed for **Serverless** scenarios.
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