嵌入式内对齐及相关位运算

Posted on 2021-07-28 Edited on 2023-07-05 In C , Memory
Symbols count in article: 1.5k Reading time ≈ 1 mins.

嵌入式内存对齐及位运算解析

Linux Debugging Tools

Posted on 2021-07-22 Edited on 2023-07-05
Symbols count in article: 384 Reading time ≈ 1 mins.

Linux 调试工具

优化 c 程序可执行文件大小

Posted on 2021-07-13 Edited on 2023-07-05 In C , GCC
Symbols count in article: 2.2k Reading time ≈ 2 mins.

优化 elf 大小的各种方式

eCos3.0-dlmalloc

Posted on 2021-07-13 Edited on 2023-07-05
Symbols count in article: 247 Reading time ≈ 1 mins.

Ref

ubuntu 20.04 GitBook 升级

Posted on 2021-07-12 Edited on 2023-07-05 In ubuntu
Symbols count in article: 1.2k Reading time ≈ 1 mins.

ubuntu 20.04 下 GitBook 运行出现错误

$ gitbook serve
Live reload server started on port: 35729
Press CTRL+C to quit ...

/usr/local/lib/node_modules/gitbook-cli/node_modules/npm/node_modules/graceful-fs/polyfills.js:287
      if (cb) cb.apply(this, arguments)
                 ^

TypeError: cb.apply is not a function
    at /usr/local/lib/node_modules/gitbook-cli/node_modules/npm/node_modules/graceful-fs/polyfills.js:287:18
    at FSReqCallback.oncomplete (fs.js:184:5)

ubuntu20.04 ssl 导致 svn update失败

Posted on 2021-06-07 Edited on 2023-07-05 In ubuntu
Symbols count in article: 1.7k Reading time ≈ 2 mins.

升级 ubuntu 20.04 后 svn update 失败

svn: E170013: Unable to connect to a repository at URL 'https://svn.xxx.com
svn: E120171: Error running context: An error occurred during SSL communication

DVB PSI/SI 组成

Posted on 2021-06-03 Edited on 2023-07-05 In DVB
Symbols count in article: 1.8k Reading time ≈ 2 mins.

DVB PSI 基础知识

强制删除未完全安装包

Posted on 2021-04-20 Edited on 2023-07-05 In ubuntu
Symbols count in article: 555 Reading time ≈ 1 mins.

ubuntu 20.04 安装 touchpad-indicator.deb 因为依赖问题导致安装失败，卸载时出现如下问题

$ sudo apt remove touchpad-indicator
/usr/sbin/deluser: The user `backup' is not a member of group `input'.
dpkg: error processing package touchpad-indicator (--remove):
 installed touchpad-indicator package post-removal script subprocess returned error exit status 6

$ sudo dpkg -l "touchpad-indicator"
rH xxx xxx

touchpad-indicator 的 BUG，需要将 backup 加入 input 组，但是卸载时会将用户删除，不可行

强制卸载如下：

$ sudo mv /var/lib/dpkg/info/ /var/lib/dpkg/info_old/
$ sudo mkdir /var/lib/dpkg/info/
$ sudo apt-get update

进一步可以清除 info_old 中 touchpad-indicator.* 并将 info_old 还原

jenkins-shell-echo-off

Posted on 2021-04-19 Edited on 2023-07-05 In Tools , CI
Symbols count in article: 240 Reading time ≈ 1 mins.

Problem:

# jenkins shell
08:06:57 + export KEYPWD=secretPwd
08:06:57 + KEYPWD=secretPwd

原因：

By default, Jenkins launches Execute Shell script with set -x. This causes all commands to be echoed

$ man bash
    -x        Print commands and their arguments as they are executed.

解决方案：

#!/bin/bash +x

tcp 性能优化

Posted on 2021-03-30 Edited on 2023-07-05 In Linux , Socket , Network , TCP
Symbols count in article: 5.2k Reading time ≈ 5 mins.

Packet Size ,Window Size and Socket Buffer In TCP
Nagel and Delayed Ack
SO_SNDBUF and SO_RCVBUF
TCP Window FULL
TCP Window ZERO
sack
BDP(bandwidth-delay product) and RTT(round trip time)
重传超时时间(RTO)
Interactive Data Flow and Bulk Data Flow
RWND and CWND

tcp 选项 SO_REUSEADDR

Posted on 2021-03-29 Edited on 2023-07-05 In Linux , Socket , Network , TCP
Symbols count in article: 454 Reading time ≈ 1 mins.

SO_REUSEADDR 用于调整解决地址复用问题

ssh 升级导致 git clone 失败

Posted on 2021-03-18 Edited on 2023-07-05 In ubuntu
Symbols count in article: 435 Reading time ≈ 1 mins.

错误信息

Unable to negotiate with 192.168.110.254 port 29418: no matching key exchange method found. Their offer: diffie-hellman-group14-sha1,diffie-hellman-group1-sha1