Survivor Guide to Develop on Windows

Guide written for Linux developers.

Useful tools

Configure newly installed Windows

  • Disable UAC
  • Disable Windows Firewall

Windows console

  • Kill a blocked command (harder than CTRL+c): CTRL + Scroll Lock key. (send a SIGBREAK signal)

Note: On my Lenovo T430 laptop, I have to use the “Fn” key:

  • Fn + B: Break
  • Fn + P: Pause
  • Fn + S: SysRq

Alternative terminals for Windows:

cmd.exe (Windows “shell”, Windows console, the MS-DOS black window)

  • Change prompt: set PROMPT=$P$G
  • Redirect stdout and stderr into the file outlog.log: command >output.log 2>&1
Windows command UNIX command Comment
set env Display all environment variables
type file.exe cat file.txt Display the content of file.txt
echo %PATH% echo $PATH Display the value of the PATH environment variable
RMDIR /S /Q dir rm -rf dir Remove a directory and its content
cmd > log cmd > log Redirect command stdout into a new log file
cmd >log 2>&1 cmd >log 2>&1 Redirect command stdout and stderr into a new log file
cmd >NUL cmd >/dev/null Ignore command stdout (redirect it to null)
echo %errorlevel% echo $? Display the exit code of the previous command
``set PROMPT=$$ `` export PS1='$ ' Change the command line prompt to ``$ ``
dir NAME /s /p find -name NAME Find a file by its name in subdirectories
shutdown /p /f sudo poweroff Turn off the computer
findstr PATTERN *.c grep PATTERN *.c Search PATTERN in files with name ending with .c
cd pwd Current directory

Get usage:

findstr /?

grep in subdirectories:

findstr /S PATTERN *.c

To emulate top on Windows, run powershell.exe and type:

while (1) { ps | sort -desc cpu | select -first 15; sleep -seconds 2; cls }

Press CTRL+c to stop it.

Configure vim on Windows

  • Right click on gvim: Run as administrator
  • Open /program files (x86)/vim/_vimrc
  • Comment the lines source $VIMRUNTIME/mswin.vim and behave mswin
  • Add custom config

Mount Windows directory on Linux

Command to mount the Widows “test” directory locally to ~/mnt, local files will be owned by the user haypo:haypo:

sudo mount.cifs '//192.168.0.14/test' ~/mnt -o 'user=USERNAME,pass=PASSWORD,uid=haypo,gid=haypo'

Visual Studio

Flavors:

  • Express
  • Professional: enough to build Python
  • Ultimate

Versions:

Visual Studio MSVC++ _MSC_VER
2017 14.1 1910
2015 14.0 1900
2013 12.0 1800
2012 11.0 1700
2010 10.0 1600
2008 9.0 1500
2005 8.0 1400
2003 7.1 1310
— 7.0 1300
— 6.0 1200
— 5.0 1100

Configure a shell to use the VS C compiler in 64-bit mode:

"%VS140COMNTOOLS%\..\..\VC"\vcvarsall.bat amd64

Argument:

  • x86: compile in 32-bit mode
  • amd64: compile in 64-bit mode
  • x86_amd64: cross-compile to 64-bit mode on a 32-bit system

Configuration

Git configuration file

Filename: C:\Users\haypo\.gitconfig. Run cmd.exe as administrator to be allowed to create symbolic links.

Windows console, cmd.exe

Right click on the title, Properties: set Buffer Size of Command History to 999 (default: 50).

Create a Windows VM on Linux to develop (VS)

Get Windows install ISO:

Get a Windows Product key:

Create a VM from the ISO with a disk of 70 GB.

Compared to Windows 10 and older, Windows 11 requires two things: a TPM device and SecureBoot. The Qemu Q35 machine type supports SecureBoot. A UEFI image is also needed for SecureBoot: on Linux, the OVMF image (port of Intel’s tianocore firmware) can be used for that,

Fedora: install OVMF image with: sudo dnf install edk2-ovmf.

Customize the VM:

  • Add device: TPM (emulated).

  • Edit the XML to configure SecureBoot, set machine type to pc-q35-6.2, load the UEFI image, enable SMM (Secure Management Mode) feature:

    <os>
    <type arch="x86_64" machine="pc-q35-6.2">hvm</type>
    <loader readonly='yes' secure='yes' type='pflash'>/usr/share/OVMF/OVMF_CODE.secboot.fd</loader>
</os>
<features>
    ...
    <smm state='on'/>
</features>

When I tried to use the q35 machine type, it became pc-q35-6.2.

Not tested, it seems like the following XML is enough to enable SecureBoot:

<os firmware='efi'>
  <loader secure='yes'/>
</os>

Command to get the OVMF image path:

$ rpm -ql edk2-ovmf | grep secboot
/usr/share/OVMF/OVMF_CODE.secboot.fd

Links:

Windows variants

To develop on CPython: get a “multi-version” of Windows 10 (no N, KN or VL variant) and use a “Pro - Retail” product key. Create of a VM with 60 GB of disk (prevously I used 40 GB, it was too small).

Flavors:

  • Family: basic feature set
  • Pro: more features
  • Entreprise: even more features

Variants:

  • “N”: Not with Media Player; for Europe.
  • “KN”: specially designed for Korean market and does not include Windows Media Player (WMP) and an instant messenger.
  • “VL”: Volume License, a single license key can be used to activate multiple installations of Windows 10. This is usually used by large enterprises.
  • “S”: “Windows 10 S can only run apps from the Windows Store”. Windows 10 S is designed to run well even on lower-end laptops. Windows 10 S is focused on speed, better battery life, and higher performance.

Some Windows error codes

  • 5: ERROR_ACCESS_DENIED: Access is denied.
  • 996: ERROR_IO_INCOMPLETE: Overlapped I/O event is not in a signaled state.
  • 10060: WSAETIMEDOUT

See the full list of Windows System Error Codes.

Windows exceptions

OpenSSH server

sshd_config

Config:

PubkeyAuthentication yes
PasswordAuthentication yes  # optional
#StrictModes yes

Copy your SSH key

Open C:\Users\vstinner\.ssh\authorized_keys file and put your public key there. Then fix file permissions:

icacls.exe "C:\Users\vstinner\.ssh\authorized_keys" /inheritance:r /grant "Administrators:F" /grant "SYSTEM:F"

If your user is an administrator, you should edit the file C:\ProgramData\ssh\administrators_authorized_keys instead. Again, you need to change the permissions:

icacls.exe "C:\ProgramData\ssh\administrators_authorized_keys" /inheritance:r /grant "Administrators:F" /grant "SYSTEM:F"

Documentation: OpenSSH key management.

Enable sshd server logs

  • As an administrator, edit C:\ProgramData\ssh\sshd_config
  • Add SyslogFacility LOCAL0.
  • Restart the sshd server: net stop sshd and then net start sshd (type these commands in an administrator terminal).

Enable sshd server

  • Go to Settings
  • Search for “Manage Optional Features”
  • Add an optional feature: “OpenSSH Server”
  • Install it.
  • Go to the Windows Start menu, search for Services.
  • In Services, search for the OpenSSH SSH Server.
  • Right click, properties:
    • Starting type: Automatic.
    • Click: OK
  • Right click: Start.

To use the OpenSSH server from Microsoft (the “Optional feature”), you need at least Windows 10 build 1803. Before, this flavor was unusable.

  • Go to settings, search for “Manage Optional Features”: enable OpenSSH

  • In my case, I had to run \Windows\System32\OpenSSH\ssh-keygen -A

  • The SSH private key is stored in %ProgramData%\ssh\ssh_host_ed25519_key. This file must be owned by SYSTEM and the only permission must be that SYSTEM is allowed to Read this file.

  • To allow incoming TCP connections to port 22 (SSH), run PowerShell as administrator and type:

    New-NetFirewallRule -Name sshd -DisplayName 'OpenSSH SSH Server' -Enabled True -Direction Inbound -Protocol TCP -Action Allow -LocalPort 22

  • Copy your SSH public key into C:\Users\vstinner\.ssh\authorized_keys (replace vstinner with your username!)

  • Go to Windows Menu>search for “Services”. In Services, search for “OpenSSH Server”: click on Start.

  • If OpenSSH server doesn’t work, look into %ProgramData%\ssh\Logs\sshd.log

  • If the server works, you can change the Service start from Manual to Automatic.

To debug, you can install psexec, open a shell as SYSTEM with psexec -i -s -d cmd.exe and then type: C:\Windows\System32\OpenSSH\sshd.exe to run the SSH server in foreground.

Files and directories:

  • C:\Windows\System32\OpenSSH\sshd.exe: the SSH server program
  • C:\ProgramData\ssh\ssh_host_ed25519_key: SSH server private key
  • C:\ProgramData\ssh\sshd_config: SSH server configuration file
  • C:\ProgramData\ssh\Logs\sshd.log: SSH server logs

Misc

  • Get system load:: wmic cpu get loadpercentage

Disable Windows Defender Realtime protection

On an idle Windows VM, the VM uses between more than 150% of the CPU. If I move the mouse cursor, the CPU usage goes to 50%. It is the msmpeng.exe process which uses the CPU. “ps” in PowerShell and the Task Manager don’t agree on the CPU usage: 50% according to ps, 2% according to the Task Manager…

If I disable Real Time protection in Windows Defender, the feature is enabled again at next reboot…

I had to add a key into registry to ensure that Windows doesn’t reenable Real Time protection after reboot:

  • run regedit.exe
  • Go to HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftWindows Defender
  • Create a “DWORD (32-bit)” key called “DisableAntiSpyware”, set its value to 1.
  • Done.

Maximum path length

Application manifest to opt-in for “long path”:

<application xmlns="urn:schemas-microsoft-com:asm.v3">
  <windowsSettings>
    <longPathAware xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">true</longPathAware>
  </windowsSettings>
</application>

An application only supports long if the system supports long path and the application opts in for long path.

C languages: Windows types

Windows Data Types:

  • LPCTSTR: CONST WCHAR * if UNICODE defined, CONST CHAR * otherwise
  • UINT:: unsigned int

C Runtime library (CRT)

Visual Studio provides a C Runtime library (CRT). Its source code can be found in: “%ProgramFiles(x86)%Windows Kits10Source10.0.[version]ucrtenv”.

Debug Windows Update failure

  • Google the error code
  • Open cmd.exe as an adminitrator and run: sfc /scannow (SFC fixes system files integrity)
  • Open cmd.exe as an adminitrator and run: DISM /Online /Cleanup-Image /RestoreHealth (repair corrupted files of installed packages)

Not tested: CHKDSK C: /F /R (/F repairs errors, /R checks for bad sectors).

Time

Kernel ticks:

  • The kernel uses an interruption at 64 Hz: 15.625 ms per tick
  • NtQueryTimerResolution() gives the min/max and current resolution of the tick

Wait:

  • WaitForSingleObject(): resolution of 1 tick
  • Sleep(): resolution of 1 tick

System clock:

  • GetSystemTimeAsFileTime(): resolution of 1 tick
  • GetSystemTimePreciseAsFileTime() (Windows 8 and newer)

Monotonic clock:

  • GetTickCount64(): resolution of 1 tick

Performance counter:

  • QueryPerformanceCounter(): resolution of 1 / frequency (100 ns on Windows 10)
  • QueryPerformanceFrequency(): 10 MHz on Windows 10

Timer:

  • CreateWaitableTimer()
  • SetWaitableTimer(): resolution of 100 ns

Multimedia API, winmm.lib and timeapi.h:

  • Frequency up to 1 kHz: 1 ms per tick
  • timeBeginPeriod()
    • “Setting a higher resolution can improve the accuracy of time-out intervals in wait functions. However, it can also reduce overall system performance, because the thread scheduler switches tasks more often. High resolutions can also prevent the CPU power management system from entering power-saving modes. Setting a higher resolution does not improve the accuracy of the high-resolution performance counter.”

See also:

Chocolatery

Package manager for Windows prodiving free softwares: https://chocolatey.org/

Packages:

  • firefox
  • git
  • vim

Run cmd as an administrator and type:

choco update all