Eureka

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概述(#14)

ARB_point_parameters允许用户设置点的扩展几何特征。这些点的几何特征主要用来渲染粒子或微小光源，通常被称为光点(Light Points).

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CUDA Samples

CUDA Samples是示范CUDA编程概念的软件包。自CUDA 4.1开始，CUDA Toolkit搭载了CUDA Samples安装包。CUDA Samples的目录结构如下：

  • 0_Simple
  • 1_Utilities
  • 2_Graphics
  • 3_Imaging
  • 4_Finance
  • 5_Simulations
  • 6_Advanced
  • 7_CUDALibraries
  • EULA.txt
  • Makefile
  • bin
  • common

Incompatible GCC Version

如果你安装的是CUDA Toolkit 9.0, 它所兼容的GCC Version最高到 gcc-6. 如果你的环境是Ubuntu 19.10，那么在编译CUDA Samples之前，你需要降级GCC Version到6或以下，方法如下：

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sudo apt install gcc-4.8
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 10

update-alternatives 更新/etc/alternatives目录下的gcc链接指向/usr/bin/gcc-4.8, 它的最后的参数10是指priority.

NOTE: 安装CUDA Toolkit时会进行GCC Compatibility检查，但是可以通过下面选项忽略这个检查：

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sudo sh cuda_9.0.176_384.81_linux.run --override

Build Samples

构建CUDA Samples可以在顶层目录构建所有Samples, 也可以到单个目录下构建一个Sample. 为了能够让可执行文件能够链接到GPGPU-Sim的libcudart.so,需要这样运行构建命令：

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make NVCCFLAGS="--cudart shared"

Run Samples

在 Run Samples 之前，需要配置GPGPU-Sim的仿真参数和libcudart.so的路径:

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cp /path/to/gpgpu-sim/configs/tested-cfgs/SM2_GTX480/* /path/to/executables
source /path/to/gpgpu-sim/setup_environment

现在可以让CUDA Samples运行在GPGPU-Sim仿真器上了。

Documents

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find /usr/local/cuda-9.0 -name '*.pdf' -printf '%f\n'

通过上面的命令可以找到介绍如何编写Samples以及相关的图形学原理的文档，亦包括CUDA编程的相关文档，可供初学者参考。

References:

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Visual Block Selection

  • 选择 {}(curly braces) 之间的行(包括 {})

    • v%

  • 选择 {}(curly braces) 之间的行(不包括 {})

    • vi{

注意：光标必须放在 { 或者 }

Copy & Paste

Copy to clipboard

  • Normal 模式
    • "+y

Paste from clipboard

X11 window system 有 3 个 selections:

  • PRIMARY 表示当前的可见 selection
  • SECONDARY
  • CLIPBOARD 通常所说的剪贴板，用来完成剪贴，复制和粘贴操作

Vim 有两个专门的寄存器分别与 PRIMARY selection 和 CLIPBOARD selection 对应

  • "* (quotestar) PRIMARY
  • "+ (quoteplus) CLIPBOARD

如果要在 Vim 内部剪贴，复制/粘贴就使用 quotestar, 如果要将内容剪贴，复制/粘贴到系统剪贴板，就使用 quoteplus

举个例子，在 WSL Ubuntu 里如果想粘贴 Windows 剪贴板里的内容到 vim (最好是 neovim, 因为 vim 可能未使能 clipboard)

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echo "Hello, world!" | clip.exe
  • Normal 模式
    • "+p

如果想粘贴 Ubuntu 剪贴板里的内容

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echo "Hello, world!" | xclip
  • Normal 模式
    • "*p

Copy from above or below

在 Insert 模式下

  • <ctrl-y> copies the character from the line above
  • <ctrl-e> copies the character from the line below (本行就是这样输入的)

Search & Replace

删除多行 C-style 注释

  • s;/\*\_.\{-}\*/;;

    • ; 因为要匹配 /, 为了省去转义 / 的麻烦，将 search 命令的分隔符由 / 改为 ;

    • /\* 匹配开始的 /*

    • \_. 匹配任意字符，包括 \n, 所以常用在多行匹配

    • \{-} 指非贪婪 (non-greedy) 匹配，即匹配最短的字串，默认是贪婪匹配，匹配最长的字串

    • \*/ 匹配结尾的 */

    • ;; 指使用空替换匹配结果，即删除

    • 以下是 vim 中在单行中使用的通配符 (wildcard), 这些通配符一般不能匹配换行 \n

      • . 匹配除了 \n 的任意字符
      • ^ 行首，即锚点 (anchor)
      • $ 行尾，即锚点
      • \s 匹配 space, tab, 但不匹配 \n

    • 以上通配符加上 \_ 后可以在多行匹配中使用，即也可以匹配 \n

      • \_. 匹配任意字符，包括 \n
      • \_^ 多行中第一行行首
      • \_$ 多行中最后一行行尾
      • \_s 匹配 space, tab 和 \n

删除空白行

  • g/^\s*$/d

    • g 指所有行搜索，而不是默认的光标所在行
    • ^\s*$ 匹配行首到行尾之间任意个空白字符，即空白行
    • d 删除命令 (delete)

搜索不匹配某模式的行，即反向搜索

  • /^\(\(^# .*$\)\@!.\)*$

    • / 查找命令 (search) 的提示符
    • ^\(\(The_Regex\)\@!.\)*$ 反向查找的命令固定模式，本例中 The_Regex 是 ^# .*$ 即以 # 开头的行，所以整个表达式匹配的就是不以 # 开头的所有行

  • :v/^# .*$/p

    • 与上面的反向查找命令功能相同, 但会将匹配结果显示在 Visual 模式下

大小写转换

  • s/\(^# .*$\)/\L\1/

    • \(The_Regex\) 为了向前索引，即后面 \1 所指的部分，本例中 The_Regex 是 ^# .*$, 意思同上
    • \L\1 \L 指 Lowercase, 即将 \1 匹配的结果中的所有字母都换成小写

  • s/\(^# .*$\)/\U\1/

    • 与上面的表达式功能相反，即将 \1 匹配的结果中的所有字母都换成大写 (Uppercase)

expression register

假如你在 markdown 文件里编辑一个 Table, table 的第1列是 find 的输出：一个很长的文件列表，且文件名长短不一(假如最长的文件名是 100 个字符)，你如何在 100 列插入 vertical bar (|)?

  • N,Ms/.*/\=printf('%-101s|', submatch(0))/

    • N,M 指定替换的范围
    • \= 表示使用 expression register, 这里相当于把 printf() 函数的输出导入到这里

TOhtml

vim 有一个内置的扩展 TOhtml, 可以将 vim 的 buffer 自动转成 html 文件，这个功能对于 vimdiff 时尤其有用。

  1. :[range]TOhtml range 没有时默认是整个 buffer (vimdiff 时包括左右两个 window 哦)
  2. :wqa 生成的 html 默认保存为 Diff.html
  3. 可以将生成的 html 内容直接粘贴到 jsbin.com, 然后就可以分享给他人

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X11 is designed as client-server mode. The communication between the X client and server complies with TCP protocol. Recently I have a Windows X server VcXsrv installed on my Windows 10 and I debug an OpenGL demo glxgears on the WSL2 with tcpdump.

Environment

WSL2 is equipped with its own networking interface like a virtual machine.

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$ ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.28.233.193  netmask 255.255.240.0  broadcast 172.28.239.255
        inet6 fe80::215:5dff:fe27:9562  prefixlen 64  scopeid 0x20<link>
        ether 00:15:5d:27:95:62  txqueuelen 1000  (Ethernet)
        RX packets 221579  bytes 15160108 (15.1 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 306691  bytes 15714800233 (15.7 GB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 392  bytes 43340 (43.3 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 392  bytes 43340 (43.3 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

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$ /mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe -C "ipconfig"

Windows IP Configuration


Ethernet adapter vEthernet (WSL):

   Connection-specific DNS Suffix  . : 
   Link-local IPv6 Address . . . . . : fe80::412b:ad3:5548:67ba%38
   IPv4 Address. . . . . . . . . . . : 172.28.224.1
   Subnet Mask . . . . . . . . . . . : 255.255.240.0
   Default Gateway . . . . . . . . . : 

Wireless LAN adapter ±¾µØÁ¬½Ó* 1:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . : 

Wireless LAN adapter ±¾µØÁ¬½Ó* 10:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . : 

Wireless LAN adapter WLAN:

   Connection-specific DNS Suffix  . : DHCP HOST
   Link-local IPv6 Address . . . . . : fe80::954b:e66f:4065:20af%20
   IPv4 Address. . . . . . . . . . . : 192.168.2.100
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.2.1

After starting up the X server VcXsrv, you need to export the environmnet variable DISPLAY on the WSL. In case of the vEthernet configuration changed after rebooting you’d better do it like this:

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export DISPLAY=$(grep 'nameserver' /etc/resolv.conf | awk '{print $2}'):0

NOTE: The Firewall between the host and WSL2 must be disabled or your X client can not connect VcXsrv.

Debugging

I trace the demo glxgears using gdb and tcpdump at the same time.

  • gdb
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gdb -q -tui glxgears
  • tcpdump
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sudo tcpdump -vvX not icmp and not arp and not udp and portrange 37900-37999 -w x110224.pcap
  • vv: verboser than -v
  • X: show the packet’s content
  • not icmp: filter out icmp packets
  • not arp: filter out arp packets
  • not udp: filter out udp packets
  • portrange 37900-37999: listening on the ports from 37900 to 37999
  • w x110224.pcap: save the packet captures into the file
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tcpdump -X -r x110224.pcap
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reading from file /home/luc/github/x110224.pcap, link-type EN10MB (Ethernet)
09:11:56.659816 IP 172.28.233.193.37950 > 172.28.224.1.x11: Flags [P.], seq 2796598646:2796598658, ack 1053772981, win 259, length 12
	0x0000:  4500 0034 1d84 4000 4006 fb43 ac1c e9c1  E..4..@.@..C....
	0x0010:  ac1c e001 943e 1770 a6b0 b576 3ecf 4cb5  .....>.p...v>.L.
	0x0020:  5018 0103 2223 0000 6200 0300 0400 0000  P..."#..b.......
	0x0030:  4452 4932                                DRI2
09:11:56.660218 IP 172.28.224.1.x11 > 172.28.233.193.37950: Flags [P.], seq 1:33, ack 12, win 8211, length 32
	0x0000:  4500 0048 d9d7 4000 8006 fedb ac1c e001  E..H..@.........
	0x0010:  ac1c e9c1 1770 943e 3ecf 4cb5 a6b0 b582  .....p.>>.L.....
	0x0020:  5018 2013 cf36 0000 0100 0a00 0000 0000  P....6..........
	0x0030:  0000 0000 0000 0000 0000 0000 0000 0000  ................
	0x0040:  0000 0000 0000 0000                      ........
09:11:56.660232 IP 172.28.233.193.37950 > 172.28.224.1.x11: Flags [.], ack 33, win 259, length 0
	0x0000:  4500 0028 1d85 4000 4006 fb4e ac1c e9c1  E..(..@.@..N....
	0x0010:  ac1c e001 943e 1770 a6b0 b582 3ecf 4cd5  .....>.p....>.L.
	0x0020:  5010 0103 2217 0000                      P..."...

what codes sends and receives these packets? The first two twenty-byted segments are IP header (20 bytes without option) and TCP header (20 bytes without option) separately in these packets.

The source code snippet:

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Bool
XQueryExtension(
    register Display *dpy,
    _Xconst char *name,
    int *major_opcode,  /* RETURN */
    int *first_event,   /* RETURN */
    int *first_error)	/* RETURN */
{
    xQueryExtensionReply rep;
    register xQueryExtensionReq *req;

    LockDisplay(dpy);
    GetReq(QueryExtension, req);
    req->nbytes = name ? strlen(name) : 0;
    req->length += (req->nbytes+(unsigned)3)>>2;
    _XSend(dpy, name, (long)req->nbytes);
    (void) _XReply (dpy, (xReply *)&rep, 0, xTrue);
    *major_opcode = rep.major_opcode;
    *first_event = rep.first_event;
    *first_error = rep.first_error;
    UnlockDisplay(dpy);
    SyncHandle();
    return (rep.present);
}

The gdb log:

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Starting program: /mnt/c/Users/lulu/Documents/github/demos/src/xdemos/glxgears 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Breakpoint 1, XextAddDisplay (extinfo=0x7ffff7e77380 <_dri2Info_data>, dpy=0x55555555d2a0, 
    ext_name=0x7ffff7e76780 <dri2ExtensionName> "DRI2", hooks=0x7ffff7e767a0 <dri2ExtensionHooks>, nevents=0, data=0x0)
    at extutil.c:103
XInitExtension (dpy=dpy@entry=0x55555555d2a0, name=name@entry=0x7ffff7e76780 <dri2ExtensionName> "DRI2")
    at InitExt.c:44
XQueryExtension (dpy=dpy@entry=0x55555555d2a0, name=name@entry=0x7ffff7e76780 <dri2ExtensionName> "DRI2", 
    major_opcode=major_opcode@entry=0x7fffffffd984, first_event=first_event@entry=0x7fffffffd988, 
    first_error=first_error@entry=0x7fffffffd98c) at QuExt.c:39
$2 = {
  reqType = 0x62, 
  pad = 0x0, 
  length = 0x3, 
  nbytes = 0x4, 
  pad1 = 0x0, 
  pad2 = 0x0
}
$3 = {
  type = 0x1, 
  pad1 = 0x0, 
  sequenceNumber = 0xa, 
  length = 0x0, 
  present = 0x0, 
  major_opcode = 0x0, 
  first_event = 0x0, 
  first_error = 0x0, 
  pad3 = 0x0, 
  pad4 = 0x0, 
  pad5 = 0x0, 
  pad6 = 0x0, 
  pad7 = 0x0
}

$2 is Request packet content to VcXsrv, $3 is Reply packet content from VcXsrv. Even that we can notice the three-way handshake of TCP from the zero-lengthed packet in x110224.pcap.

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Overview

Mesa 包含了各种 GPU/CPU 的 OpenGL, OpenCL, Vulkan 实现(Usermode Driver), 也包括 GLX, EGL, GBM 等协议的实现。

  • Vulkan 驱动
codename directories platforms
anv src/intel/vulkan, src/intel/vulkan_hasvk Alder Lake-P
asahi src/asahi/vulkan Apple M1, M2
lpv src/gallium/drivers/llvmpipe CPU
panvk src/panfrost/vulkan RK3399
v3dv src/broadcom/vulkan Raspberry Pi

Build

Build Dependencies (since mesa-25.0.0)

dep apt-get version required yet another install
/usr/bin/glslangValidator glslang-tools https://github.com/KhronosGroup/glslang
/usr/bin/rustc rustc 1.78.0 or newer `curl --proto ‘=https’ --tlsv1.2 -sSf https://sh.rustup.rs
bindgen (rust package) cargo 0.65 or newer cargo install bindgen-cli
libclc-dev libclc-17-dev not required if -Dmesa-clc=auto
+ libdrm libdrm-dev 2.4.121(120 ok2.0) https://gitlab.freedesktop.org/mesa/drm
llvm llvm-17-dev (17.0.6 ok2.0) https://github.com/llvm/llvm-project
libLLVMSPIRVLib.so.17 llvm-spirv-17 (17.0.0 ok2.0) https://github.com/KhronosGroup/SPIRV-LLVM-Translator
+ LLVMSPIRVLib.h llvmspirvlib-17-dev (absent ok2.0) https://github.com/KhronosGroup/SPIRV-LLVM-Translator
clang-cpp libclang-cpp17-dev (17.0.6 ok2.0) not required if -Dmesa-clc=auto
* clang-dev libclang-17-dev Debian package issue
xshmfence libxshmfence-dev (1.3 ok2.0) required if -Dplatforms=x11
xxf86vm libxxf86vm-dev (1.1.4 ok2.0) required since -Dglx-direct=true by default
xrandr libxrandr-dev (1.5.2 ok2.0) required since -Dxlib-lease=true
cbindgen (rust package) cargo 0.28.0 cargo install cbindgen; required if -Dgallium-drivers=nouveau

NOTE:

  • (*) 表示本来不需要的依赖

  • (+) 在 OpenKylin 2.0 的源里没有，需要源码构建

  • Ubuntu 22.04

书到用时方恨少，包要装时不好找

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sudo apt install -y cmake ninja-build bison flex g++ git pkg-config python3-setuptools python3-lz4 \
    python3-jinja2 libssl-dev libelf-dev libboost-dev libglm-dev libtinyobjloader-dev libstb-dev \
    libpng-dev wayland-protocols libwayland-dev libdecor-0-dev freeglut3-dev libglfw3-dev libexpat1-dev libglvnd-dev \
    libx11-dev libxext-dev libxshmfence-dev libxrandr-dev libxxf86vm-dev libxfixes-dev libx11-xcb-dev \
    libxcb1-dev libxcb-randr0-dev libxcb-glx0-dev libxcb-shm0-dev libxcb-dri3-dev libxcb-dri2-0-dev libxcb-present-dev \
    libselinux1-dev libvulkan-dev vulkan-tools mesa-utils
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meson build -Dprefix=/usr/local -Dlibdir=lib/x86_64-linux-gnu -Dplatforms=x11 -Dgallium-drivers=nouveau
  • -Dprefix=/usr/local 避免覆盖系统原来的 libGL*
  • -Dlibdir=lib/x86_64-linux-gnu 设置库的安装路径为 /etc/ld.so.conf.d/x86_64-linux-gnu.conf 中搜索第一顺位的路径
  • 其他默认就好， 出现的依赖在 OpenKylin 2.0 上 apt-get 基本都能解决
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Build targets in project: 437
WARNING: Project specifies a minimum meson_version '>= 1.1.0' but uses features which were added in newer versions:
 * 1.3.0: {'rust.proc_macro', 'rust_abi arg in static_library'}

mesa 25.0.0-devel

  Directories
    prefix                       : /usr/local
    libdir                       : lib/x86_64-linux-gnu
    includedir                   : include

  Common C and C++ arguments
    c_cpp_args                   : -mtls-dialect=gnu2

  OpenGL
    OpenGL                       : YES
    ES1                          : YES
    ES2                          : YES
    Shared glapi                 : YES
    GLVND                        : YES

  DRI
    Platform                     : drm
    Driver dir                   : /usr/local/lib/x86_64-linux-gnu/dri

  GLX
    Enabled                      : YES
    Provider                     : dri

  EGL
    Enabled                      : YES
    Drivers                      : builtin:egl_dri2 builtin:egl_dri3
    Platforms                    : x11 surfaceless drm xcb

  GBM
    Enabled                      : YES
    Backends path                : /usr/local/lib/x86_64-linux-gnu/gbm

  Vulkan
    Drivers                      : amd intel intel_hasvk nouveau swrast
    Platforms                    : x11 surfaceless drm xcb
    ICD dir                      : share/vulkan/icd.d
    Intel Ray tracing            : YES

  Video
    Codecs                       : av1dec av1enc vp9dec
    APIs                         : vulkan xa

  LLVM
    Enabled                      : YES
    Version                      : 17.0.6

  Gallium
    Enabled                      : YES
    Drivers                      : nouveau
    Platforms                    : x11 surfaceless drm xcb
    Frontends                    : mesa xa
    Off-screen rendering (OSMesa): NO
    HUD lm-sensors               : NO

  Perfetto
    Enabled                      : NO

  Teflon (TensorFlow Lite delegate)
    Enabled                      : NO

  Subprojects
    paste                        : YES
    proc-macro2                  : YES (from syn => quote)
    quote                        : YES (from syn)
    syn                          : YES
    unicode-ident                : YES (from syn)

  User defined options
    libdir                       : lib/x86_64-linux-gnu
    prefix                       : /usr/local
    gallium-drivers              : nouveau
    platforms                    : x11

Found ninja-1.11.1 at /usr/bin/ninja
WARNING: Running the setup command as `meson [options]` instead of `meson setup [options]` is ambiguous and deprecated.
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