Gamma LUT property

Gamma LUT (Look-Up Table) is a property that is used to correct the color and brightness of an image or video. Gamma LUT is basically a table of values that is used to map input values to output values, for example, it may map low input values to higher output values to brighten the image.

Gamma LUT is used to adjust the gamma curve of an image or video, which means it can be used to correct the brightness and contrast of an image. This property is commonly used in image and video processing applications, such as photo editing software, video editing software, and color grading tools.

Gamma LUT can also be used to correct color shifts caused by different lighting conditions or camera settings. By adjusting the gamma curve of an image or video, it is possible to create a more natural and accurate representation of the original scene.

Linux 内核的 patch 是以纯文本的邮件形式进行提交和代码走查的，而且 patch 是先到内核子系统 maintainer 维护的 git tree, 再到 Linus Torvalds 的 main tree。本文主要是以一个 patch 提交的实例来记录一下整个过程中的一些具体操作要点，至于 kernel patch 提交的规范和操作细节内核文档 和各种博客文章有很多，这里不再赘述。

来自 ChatGPT 的解释

What is Vulkan ICD?

Vulkan ICD (Installable Client Driver) is a software component that enables the Vulkan API (Application Programming Interface) to interact with the hardware of a computer system. Vulkan is a low-level graphics API developed by the Khronos Group, which provides developers with more control over hardware resources, leading to improved performance and efficiency in graphics-intensive applications such as video games. The Vulkan ICD is responsible for managing the communication between the Vulkan API and the graphics hardware of a system. It is typically provided by the manufacturer of the graphics card as a driver for the system.

Light Display Manager 是一个轻量级的跨桌面环境的 Display Manager, 可以支持多种显示技术，如 X11, Mir, Wayland.

Build

Dependencies

• 开发包依赖

  • libpam0g-dev
  • libgcrypt20-dev
  • libglib2.0-dev
  • libxklavier-dev

• 构建工具依赖

  • intltool
  • yelp-tools
  • gtk-doc-tools

• 安装

Lightdm 可执行程序路径 /usr/sbin/lightdm, 日志默认路径 /var/log/lightdm/lightdm.log. 所以构建时可以使用

• --prefix 指定安装路径 (默认 /usr/local)
• --localstatedir 指定日志路径 (默认 $prefix/var/log/lightdm)
• --sysconfdir 指定 lightdm.conf 路径 （默认 $prefix/etc/lightdm)

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2
3

./autogen.sh --prefix=/usr --localstatedir=/var --sysconfdir=/etc --disable-tests
make -j $JOBS
sudo make install

Graphics Boot-up

flowchart TD
    A["systemd"]
    B["/usr/sbin/lightdm"]
    C["`[Seat:*]
        # Dump core
        xserver-command=X -core`"]
    D["`X
        Symbolic link to Xorg`"]

    A -- lightdm.service --> B -- /usr/share/lightdm/lightdm.conf.d/50-xserver-command.conf --> C --> D

P.S. lightdm --show-config 可以显示与 lightdm 相关的配置

《程序员的自我修养–链接，装载与库》这本书是在读研时才看的，印象很深，现在想想这本书讲的都是程序员，尤其是从事系统编程需要的知识。这里我将平时使用的跟编译，链接和构建应用程序及库相关的知识记录下来，希望以后能温故知新。

Glossary

• PoC: Proof of Concept, 概念验证
• Chisel: tExtended on Scala
• GDSII: 版图
• RTL: Register-Transfer Level, RTL 语言包括 SystemVerilog, Verilog, VHDL等
• FIRRTL: Chisel 的“翻译器”, Chisel -> Verilog
• shift left: 把验证和调试放在 tape in 阶段
• GEM5: C Simulator for GPU
• PPA: Power, Performance, Area, used in deciding how to optimize semiconductor designs

LLVM & llvm-project

LLVM 是 Low-Level Virtual Machine 的简写，但事实上它与虚拟机关系不大。我们更熟悉它是一套工具链，包括 clang /'klæŋ/, lld, lldb 等等。接触 LLVM 是因为 Mesa llvmpipe 使用 LLVM, 还有 AMDGPU 和 Radeon 的编译器后端都使用 LLVM IR，所以要编译 Mesa 的 -Dgallium-drivers=llvmpipe,radeonsi 都依赖于 LLVM 的诸多组件, 构建 Linux 内核的 eBPF 程序也依赖 LLVM, 构建 perfetto 也依赖 LLVM。这里主要记录 LLVM 的构建和使用的一些问题。

Choice of CLion

Reminiscence