Smart Pointer
smart pointer是C++11引入的，被包含在C++标准库中。smart pointer是为了管理对象的所属(object ownership)而设计的，smart pointer对象负责自动地销毁所关联对象。常见的smart pointer有:
ARB_texture_storage
ARB_texture_swizzle
ARB_shader_ballot
ARB_texture_view
vim 速查手册
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)
1 | echo "Hello, world!" | clip.exe |
- Normal 模式
"+p
如果想粘贴 Ubuntu 剪贴板里的内容
1 | 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*$/dg指所有行搜索，而不是默认的光标所在行^\s*$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)
- 与上面的表达式功能相反，即将
Debugging X11 with tcpdump
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.
1 | $ ifconfig |
1 | $ /mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe -C "ipconfig" |
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:
1 | 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
1 | gdb -q -tui glxgears |
- tcpdump
1 | 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
1 | tcpdump -X -r x110224.pcap |
1 | reading from file /home/luc/github/x110224.pcap, link-type EN10MB (Ethernet) |
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:1
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24Bool
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:1
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35Starting 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.
Notes for Mesa
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 | sh` | |
| 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
1 | 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
1 | Build targets in project: 437 |