泰晓资讯·08月 / 第三期 / 2019

Wang Chen 创作于 2019/08/16

“泰晓资讯”，广泛报道 “Linux/开源” 业界资讯。欢迎广大读者投递相关资讯来源和素材，本站将进一步收集整理后发布给大家。

Beta 6 现已发布，Android Q 正式版即将面世！

News of the final Android Q beta means the official Android Q release isn’t far away. In fact, Google says more details regarding the full-fledged release will be “coming soon.” According to Google’s own Android Q timeline, we should expect the final Android Q build to land before the end of September.

Android Q 正式版很快就要与大家见面啦！目前，项目团队正在对平台进行最后的优化与调试。Beta 6 更新中包含供 Pixel 及 Android 模拟器使用的最新 Android Q 系统映像、官方 API 29 SDK 以及升级版的 Android Studio 工具。最终版系统平台涵盖的所有特性、系统行为以及面向开发者的 API，全部都可以在 Beta 6 中找到。您可以利用这些更新，进一步打磨您的应用，确保它们做好万全准备。

关键词: Android

开发高级视频设备的新工具 - libcamera

Laurent Pinchart began his Open Source Summit Japan 2019 talk with a statement that, once upon a time, camera devices were simple pipelines that produced a sequence of video frames. Applications could control cameras using the Video4Linux (V4L) API by way of a single device node; there were “lots of knobs”, but the overall task was straightforward. That situation has changed over the years, and application developers need more help; that is where the libcamera project comes in.

摄像头设备机制复杂，需要大量硬件级别的图像处理操作。为此一些专业摄像头设备中经常会嵌入专用的 MCU 来实现处理图像的高级算法。但是在嵌入式系统中，为了节省成本，往往会采用一些便宜的摄像头（自然不含专用 MCU），为此用户不得不将原先由硬件实现的处理算法转移到 CPU 上以软件方式实现，由于摄像头设备型号繁多，这些处理程序往往需要定制，这给整体解决方案带来了不小的压力。为了解决这个问题，Linux 的媒体社区（Linux media community）最近开始与业界合作开发一个开源的，方便使用的摄像头软件开发库。这就是在今年日本开源峰会（Open Source Summit Japan 2019）上由 Laurent Pinchart 给大家带来的 libcamera 库，该软件库将为基于 Linux 的系统提供对现代摄像头的支持，这些 Linux 系统包括传统的 Linux 发行版，ChromeOS 和 Android。

关键词: Linux, camera, libcamera

Red Hat 正式宣布加入 RISC-V 基金会

While we’re still likely years away from seeing any serious RISC-V powered servers at least that can deliver meaningful performance, Red Hat has been active in promoting RISC-V as an open-source processor instruction set architecture and one of the most promising libre architectures we have seen over the years. Red Hat developers have already helped in working on Fedora’s RISC-V support and now the IBM-owned company is helping out more and showing their commitment by joining the RISC-V Foundation. Red Hat joins the likes of Google, NVIDIA, Qualcomm, SiFive, Western Digital, IBM, and Samsung as among the many RISC-V members.

虽然目前我们还无法看到实际商用化的 RISC-V 服务器，但 “红帽子（Red Hat）” 一直在积极地推动业界采用 RISC-V 这款开源的处理器指令集体系架构，并看好其成为最有前景的自由架构之一。红帽子公司的开发人员已经为 Fedora 添加了对 RISC-V 的支持，现在这家新晋为 IBM 旗下的公司正在通过加入 RISC-V 基金会来为其做出更多的贡献，从而进一步向社区展示他们的承诺。目前加入 RISC-V 基金会的成员还包括像谷歌，NVIDIA，高通，SiFive，西部数据，IBM 和三星等众多公司。

关键词: Red Hat, RISC-V

内核进程管理新接口 pidfd 即将就绪

Over the last few kernel releases, the kernel has gained the concept of a “pidfd” — a file descriptor that represents a process. What started as a way of sending signals to processes without race conditions has evolved into a more complete process-management interface. Now one of the last pieces is being put into place: the ability to wait for processes using pidfds. But, naturally, that API has had to go through some revisions first.

最近 Christian Brauner 正在为内核提交和 “pidfd” 有关的剩下的几个重要的补丁，其中之一是 “pidfd: waiting on processes through pidfds”。一旦所有的相关补丁就绪，我们将迎来一个全新的进程管理接口，我们将不再依赖传统的 pid，而将是 pidfd。据了解， Android 系统将首先采用该机制对系统进程进行管理。感兴趣的读者可以在 LWN 内核文章列表中搜索关键字 “pidfd” 以了解更多内容。

关键词: Linux, 进程管理, pidfd

好消息，以后我们将能在 Linux 上直接运行为 Mac 编译的二进制程序

There is an increasingly active development effort, known as Darling, that is aiming to provide a translation layer for macOS software on Linux; it is inspired in part by Wine. While Darling isn’t nearly as mature as Wine, contributors are continuing to build out capabilities that could make the project more useful to a wider group of users in the future.

目前有个名叫 Darling 的项目其活跃度正在不断提升，这个项目的目标是希望能在 Linux 上提供一个面向 macOS 软件的 translation layer（翻译层），这有点类似 Wine 所做的工作。Darling 比起 Wine 来说，成熟度差得尚远，希望最终能获得像 Wine 那样的成功，这样大量的 macOS application 都能在 Linux 上跑起来。Wine 花了很多年才稳定下来，并且一直在持续开发来提供对更多 application 的支持。对 Darling 来说估计也是类似的策略。可以确定的是，目前已经有不少开发者对此深表兴趣并且正全力为此而努力。

关键词: Linux, Mac, Darling

期待已久的新特性 - 支持 BPF 中的循环操作 - 将随内核 5.3 版本正式合入主线

BPF programs have gained significantly in capabilities over the last few years and can now perform many useful operations. That said, BPF developers have had to work around an annoying limitation until recently: they could not use loops. This restriction was recently lifted by a patch set from Alexei Starovoitov that was merged for Linux 5.3. In addition to adding support for loops, it also greatly decreases the load time of most BPF programs.

BPF program 在过去几年中性能已经大大提升，目前能支持不少很实用的操作了。但就在不久以前，BPF 的开发者还需要面对一个很讨厌的限制：即无法在 BPF 应用中使用循环，为此大家不得不一直采用一些 work around。但近期 Alexei Starovoitov 提交了一组补丁终于能够解决这个问题了。该组补丁已经合入内核的 5.3 版本，除了增加循环功能支持以外，针对大多数 BPF program 还能够大大降低加载所需要的时间。

关键词: Linux, BPF