VirtualBox

1. Terminology
2. Installation
3. Schema
4. Windows XP 32-bit VM
   1. Start VM with VRDE
   2. Manage VMs on Command Line
   3. Guest OS Configurations
   4. USB Supoort
   5. Host-only networking
   6. IDE Drive Port Limit
   7. Delete VM
5. Windows Embedded Standard 7 x86 VM
6. Android-x86 VM
7. Arch Linux x86_64 VM
   1. VirtualBox GuestAdditions
   2. VirtualBox sharedfolder
   3. Expand VDI Size
8. CentOS 8.2 Amd64
9. References

This post indroduces installing VirtualBox in Gentoo host.

Terminology

1. Host OS

   Operating system where VMM runs.

2. Guest OS

   Operating system runs over VirtualBox.

3. VirtualBox

   A virtual machine manager (VMM) owned by Orcale, also named as Base package.

   Once installed, it will insert VirtualBox kernel modules into the host OS, like vboxdrv.

4. Oracle VM VirtualBpx Extension Packs

   A proprietary bundle of packages that extends the functionality of the Base Package, like USB 3.0, VirtualBox Remote Desktop Protocol (VRDP), webcam etc.

   Extension Packs is optional. However, if you choose to install, then make sure it has the same version as the Base Package.

   Similar to the Base, Package, Extension Packs also presents as kernel modules on host OS, like vboxnetadp and vboxnetflt.

5. Oracle VM VirtualBox GuestAdditions

   Package to be installed inside the guest OS that optimizes performance and usability, like mouse pointer integration, shared folders, shared clipboard, seamless windows, time synchroniation with host OS etc.

   GuestAdditions also serve as kernel modules but in guest OS, like vboxsf, vboxvideo, and vboxguest.

6. Make sure relevant versions match.

   1. VirtualBox. Versions of Base Package, Extension Packs and GuestAdditions must match.
   2. Guest OS. Kernel modules are built against the current kernel. When VirtualBox is upgraded, kernel modules on host OS is re-built automatically. However, if guest OS kernel is changed, we should re-build the guest kernel modules manually (i.e. GuestAdditions).

Installation

1. VirtualBox depends on QT as GUI. But I would like a XFCE4 desktop without any QT packages. QT related USE flags are disabled in Gentoo make.conf.

   So I will emerge VirtualBox without GUI. To manage VMs, resort to CLI.

2. USEs

   root@tux / # echo "app-emulation/virtualbox headless additions extensions" > /etc/portage/package.use/virtualbox
   

   1. headless builds VirtualBox without any graphic frontend.

   2. attitions for Guest Addtitions.

      Since VirtualBox 5, this USE is removed. Emerge app-emulation/virtualbox-additions manually.

   3. extension for Extension Packs.

3. Build

   root@tux / # emerge -avt app-emulation/virtualbox
   root@tux / # emerge -avt app-emulation/virtualbox-additions (>=5)
   root@tux / # emerge -avt app-emulation/virtualbox-extpack-oracle (>=5)
   

   It reminds accepting PUEL licence. Refer to VirtualBox wiki.

   If fail to emerge VirtualBox, then probably you should bump to a newer version. Lastest Linux kernel usually requires lastest VirtualBox.

4. Group - vboxusers

   root@tux / # gpasswd -a <username> vboxusers
   

   Add current username to vboxusers group. Refer to in newgrp in Wireshark post.

5. Kernel modules

   root@tux / # modinfo vboxdrv vboxnetadp vboxnetflt vboxpci
   root@tux / # modprobe -v vboxdrv vboxnetadp vboxnetflt vboxpci
   

   1. If you launch VirtualBox frequently, add these modules to /etc/conf.d/modules for automatic loading on boot.
   2. vboxdrv is the core module for host OS and must always be present. vboxnetadp and vboxnetflt are required for any VM networking beyond the default NAT mode (i.e. host-only, bridged etc.).

   When booting into a new Linux kernel (i.e kernel upgrading), you could no longer load modules like vobxdrv.

   # modprobe vboxdrv
   modprobe: FATAL: Module vboxdrv not found.
   

   Read the first reference on Kernel driver not installed section. The solution is to rebuild VirtualBox external modules:

   # emerge -avt1 app-emulation/virtualbox-modules
   # -or-
   # emerge -avt1 @module-rebuild
   

   More details in Upgrade kernel to unstable 4.0.0.

6. Up to now everyting related to VirtualBox VMM is prepared on host OS. Next is to create VM through CLI.

   On macOS, use brew cask to install virtualbox and virtualbox-extension-pack.

7. Remove quotes around sysmbol ~ and symbol $.

   # /etc/udev/rules.d
   
   # Correct /dev/{vboxdrv,vboxdrvu,vboxnetctl} permissions to 0600
   KERNEL=="vboxdrv", NAME="vboxdrv", OWNER="root", GROUP="vboxusers", MODE="0660"
   KERNEL=="vboxdrvu", NAME="vboxdrvu", OWNER="root", GROUP="vboxusers", MODE="0660"
   KERNEL=="vboxnetctl", NAME="vboxnetctl", OWNER="root",GROUP="vboxusers", MODE="0660"
   

   To load the new rule, execute udevadm trigger.

Schema

1. Avoid 64-bit guest OS. 64-bit OS occupies one third more resources (disk, memory) than the 32-bit version. What was worse, it seems VBoxGuestAddtions-amd64.exe makes no difference on the guest (double mouse, weird resolution etc.).
2. The less snapshots we create, the better is the performance.
3. Put VDI file on host's home partition for better performance.

Windows XP 32-bit VM

VM won't even start without QT GUI support. But VRDP helps! VRDP is a replacement of QT GUI!

1. First create VM with VirtualBox CLI;
2. Enable VRDP support for VM;
3. Connect to headless VM by VRDP client FreeRDP.

VBoxManage createvm:

user@tux ~ $ VBoxManage list ostypes
user@tux ~ $ VBoxManage createvm --name WinXP32 --ostype WindowsXP --register --basefolder ~/Documents/VirtualBox/Machines
user@tux ~ $ VboxManage list vms
user@tux ~ $ VBoxManage registervm ~/Documents/VirtualBox/Machines/WinXP32/WinXP32.vbox (opt); vboxmanage list vms
user@tux ~ $ VBoxManage modifyvm WinXP32 --memory 384 --acpi on --nic1 nat --nictype1 Am79C973 --audio alsa --audiocontroller ac97 --usb on --usbehci on --vrde on --vrdeaddress 127.0.0.1 --vrdeport 5001,5010-5012 --clipboard bidirectional
user@tux ~ $ VBoxManage createmedium --filename ~/Documents/VirtualBox/Machines/WinXP32/WinXP32.vdi --size 5000 (omitted)
user@tux ~ $ VBoxManage storagectl WinXP32 --name "IDE Controller" --add ide --controller PIIX4
user@tux ~ $ VBoxManage storageattach WinXP32 --storagectl "IDE Controller" --port 0 --device 0 --type hdd --medium ~/Documents/VirtualBox/Machines/WinXP32/WinXP32.vdi
user@tux ~ $ VBoxManage storageattach WinXP32 --storagectl "IDE Controller" --port 0 --device 1 --type hdd --medium /path/to/ISO (omitted)
user@tux ~ $ VBoxManage storageattach WinXP32 --storagectl "IDE Controller" --port 1 --device 0 --type dvddrive --medium /usr/share/virtualbox/VBoxGuestAdditions.iso (or --device 1 --medium additions)
user@tux ~ $ VBoxManage sharedfolder add WinXP32 --name WLshare --hostpath /media/Misc/VMs/WLshare

Here, I re-use an existing .vdi instead of guest installation ISO, thus avoiding guest OS installing process. Apparently, createmedium prodecure is omitted.

1. ostypes

   List supported OSes. I am going to install Windows XP 32-bit. The value is WindowsXP.

2. createvm
   • --name should be enclosed by double quotes in case of white spaces.
   • --register to register the VM instantly, or run VBoxManage registervm afterwards.
   • --basefoler can be used to specify this VM's files location (i.e. set to NTFS partition). If not set, it will default to ${HOME}/.VirtualBox/Machines which is different from VirtualBox confiuration file.

3. registervm

   Bug: --register of createvm failed to register the VM though it reports negtive success. Possible solutions:

   1. Specifically add --basefolder to createvm –register.
   2. Pass full path of .vbox file to registervm on a separate shell command.
4. modifyvm
   • --nictype1 Am79C973 sets virtual Ethernet hardware to AMD PCNet FAST III (Am79C973). VirtualBox 5 now use Intel PRO/1000 T Server (82543GC) as default, which requires extra drivers installed.
   • --audio alsa could be pulse instead.
   • --vrde on is to enable VRDP support thus I can remotely connect to the VM by RDP client.
   • ` –usb on –usbehci on enables USB 1.0 and 2.0. To enable 3.0, use –usbxhci on`.
   • --vrdeaddress set to loopback address. If unset, it binds to all host network interfaces accepting both IPv4 and IPv6. Refer to 127.0.0.1 vs 0.0.0.0.
   • --draganddrop option is useful if you need it. However, it is vunerable to security issue.

5. storagectl

   Set disk controller for VM. Don't use SATA related controller for WindowsXP.

6. storageattach VDI

   WinXP32.vdi is copied from some guy in QQ group, getting rid of installing VM OS from scratch.

7. storageattach

   VBoxGuestAddiontions.iso supports file sharing, mouse switch etc between host and guest. WE will install this toolbox after entering WindowsXP VM.

8. sharedfolder

   Create a folder for share on host and mount it on guest.

   After entering VM, open Windows Explorer and look for it under "My Networking Places", "Entire Network", "VirtualBox Shared Folders", "\\Vboxsvr".

   By right-clicking on a shared folder and selecting "Map network drive" from the menu that pops up, you can assign a drive letter to that shared folder.

   If you don't assign a drive letter, each time to access the shared, we have to find it under "\\Vboxsvr".

   If you cannot locate the shared folder under Windows Explorer/Network, check if Network Discovery is turned on in Control Panel (default for Home networking type). You can also try CMD:

   net use z: \\vboxsvr\WLshare
   # or
   net use z: \\vboxsrv\WLshare
   

9. Up to now, the VM is prepared! We need a RDP client.

Start VM with VRDE

VirtualBox Remote Display Protocol (VRDP) is a backwards-compatible extension to Microsoft's Remote Desktop Protocol (RDP). VirtualBox Remote Desktop Extension (VRDE) is an Oracle VRDP implementation. Apart from TCP/Ports and TCP/Address, we have:

• --vrdemulticon on allows multiple simultaneous connections to the same VM, without which we can resort to --vrdereusecon on that can cut off the current connection for the new one.
• --vrdeauthtype external requires username and password of the host before connection.

Here is FreeRDP setup details:

1. Up to now, the VM is created! But VirtualBox does not have QT GUI. We need RDP client, i.e. FreeRDP.

   root@tux / # emerge -avt net-misc/freerdp
   

2. startvm

   user@tux ~ $ VBoxManage startvm "WinXP32" --type headless
   # or
   user@tux ~ $ VBoxHeadless --startvm WinXP32
   

   VBoxHeadless is a tool the launch VM as a server mode without GUI. If you buy a VPS, the OS mostly runs in a similar mode (maybe VNC browser). Now the VM is started, but not showing up! We need to use FreeRDP to get X.

   On MacOS host, the GUI mode may report error:

   You must specify a machine to start, using the command line.

   Please disable Audio is guest VM setting. You may also want to read VirtualBox crashes after upgrading to macOS Catalina.

3. FreeRDP

   The RDP TCP port is set to an optional list 5001,5010-5012 (default 3389).

   $ xfreerdp +clipboard /w:1024 /h:576 /v:127.0.0.1:5001
   

   1. The server IP is vrdeaddress, NOT IP of guest. Since I connect to VM locally, so it 127.0.0.1. xfreerdp can add many other parameters, like window size, audio, video etc.
   2. 'Ctrl + Alt + Enter' to toggle full screen.
   3. You might found there are two mouse pointers, one for host while another for guest. Also the screen resolution is not correctly set. Install VBoxGuestAdditions we've attached the Vm. Open file explorer, installer is located in partition (D:) VirtualBox GuestAdditions, VBoxWindowsAdditions.exe. Disable Direct3D component on a low end VM.

4. Shutdown

    $ VBoxManage controlvm WinXP32 savestate/acpipowerbutton/poweroff/pause
   

   1. pause: temporarily puts a virtual machine on hold, without changing its state for good. The VM window will be painted in gray to indicate that the VM is currently paused.
   2. poweroff: has the same effect on a virtual machine as pulling the power cable on a real computer. Again, the state of the VM is not saved beforehand, and data may be lost. (This is equivalent to selecting the "Close" item in the "Machine" menu of the GUI or pressing the window's close button, and then selecting "Power off the machine" in the dialog.)
   3. savestate: saves the current state of the VM to disk and then stop the VM. (This is equivalent to selecting the "Close" item in the "Machine" menu of the GUI or pressing the window's close button, and then selecting "Save the machine state" in the dialog.) We can think savestate as suspend to disk (hibernate).
   4. acpipowerbuttion: simulates long press the PC's power buttion to shutdown directly without saving.

   Which to use, depens on:

   1. If jobs in VM is not yet finished (like editing a file), use savestate;
   2. If every jobs completed, use acpipoweroff (as long as ACPI is enabled for VM) or poweroff;
   3. If still want to leave the VM running remotely, just close the RDP window.

5. Remove guest addtions ISO

    user@tux ~ $ VBoxManage storageattach WinXP32 --storagectl "IDE Controller" --port 1 --device 0 --type dvddrive --medium emptydrive / none
   

   Detach ISO file after VBoxGuestAddtions is installed.

Manage VMs on Command Line

1. Load kernel modules.

   #!/bin/bash
   for m in vbox{drv,netadp,netflt,pci}; do modprobe -v $m; done
   echo 'VirtualBox modules loaded!'
   

2. Startup script.

   #!/usr/bin/env bash
   
   PS3='Please enter your choice on VM WinXP32: '
   options=("startvm" "rdp" "poweroff" "acpipowerbutton" "savestate" "quit")
   select opt in "${options[@]}"
   do
       case $opt in
       "startvm")
           echo "you choose to launch WinXP32"
           VBoxHeadless --startvm WinXP32
           break
           ;;
       "rdp")
           echo "you choose to connect WinXP32"
           xfreerdp +clipboard /sound /f /v:127.0.0.1:5001
           break
           ;;
       "acpipowerbutton")
           echo "you chose to acpipowerbuttion WinXP32"
           VBoxManage controlvm WinXP32 poweroff
           break
           ;;
       "savestate")
           echo "you chose to save WinXP32state"
           VBoxManage controlvm WinXP32 savestate
           break
           ;;
       "poweroff")
           echo "you chose to poweroff WinXP32"
           VBoxManage controlvm WinXP32 poweroff
           break
           ;;
       "quit")
           break
           ;;
       *) echo 'invalid option'
          ;;
       esac
   

Guest OS Configurations

After getting into the Windows XP system, we can adjust some system configurations to minimize resource consumption:

1. For English OS, then set non-Unicode language to Chinese and set the Regional Options values.
2. Disable soundman etc. with msconfig.
3. Set Wireless Zero Configuration, Windows Audio, Windows Themes etc. services to Disabled or Manual. Refer to Windows XP 终极优化.
4. If installed '迅雷', then set XLServicePlatform to Manual.
5. My Computer, Properties, Advanced, Performance, Settings, Adjust for best performance.

USB Supoort

Attach plugged in USB device to VM. First set the USB version to 1.0, 2.0 or 3.0 for VM.

user@tux ~ $ vboxmanage list usbhost
user@tux ~ $ vboxmanage controlvm WinXP32 usbattach USB-UUID
user@tux ~ $ vboxmanage list usbhost
user@tux ~ $ vboxmanage controlvm WinXP32 usbdetach USB-UUID

1. Find the USB device UUID by checking the Manufacture and Product field. Make sure the Current State field is Available.
2. Attach the USB to VM.
3. The Current State field becomes Captured (by VM).
4. Detach from VM.
5. Get UUID from vboxmanage list usbhost instead of blkid.

We can also make this attachment permanent by creating a usbfilter.

Host-only networking

Take Android-x86 for example, the very first step is to create a hostonlyif interface, as follows:

user@tux ~ $ VBoxManage hostonlyif create/remove vboxnet0
user@tux ~ $ ip link; VBoxManage list hostonlyifs
user@tux ~ $ VBoxManage hostonlyif ipconfig vboxnet0 --ip 192.168.56.1 # '--dhcp' is not supported currently
user@tux ~ $ VBoxManage modifyvm Android51 --nic2 hostonly --hostonlyadapter2 vboxnet0
user@tux ~ $ VBoxManage dhcpserver add/modify --ifname vboxnet0 (--netname HostInterfaceNetworking-vboxnet0) --ip 192.168.56.1 --netmask 255.255.255.0 --lowerip 192.168.56.100 --upperip 192.168.56.110 --enable
user@tux ~ $ VBoxManage list dhcpservers
user@tux ~ $ ip address
# boot Android51
user@tux ~ # netcfg eth1 dhcp

1. Check iptables and/or firewall.

   user@tux ~ # iptables -I INPUT 4 -i vboxnet0 -s 192.168.56.0/24 -j ACCEPT
   user@tux ~ # iptables -I OUTPUT 4 -o vboxnet0 -s 192.168.56.0/24 -j ACCEPT
   

2. Apart from NAT/bridged networking, we can use iptables redirect to let vboxnet0 traffic go outside.

3. Especially, guest VM can share host's proxy as long as it's listening on local network (i.e. 0.0.0.0). You may want to prohibit LAN devices connection to proxy.

   user@tux ~ # iptables -I INPUT 4 -i vboxnet0 -d 192.168.56.0/24 -p tcp -m tcp --dport 1080 -j DROP
   user@tux ~ # iptables -I INPUT 4 -i vboxnet0 -d 192.168.56.0/24 -p udp -m udp --dport 1080 -j DROP (opt)
   

4. Share host proxy

   Alternatively, iptables redirect vboxnet0 traffic to 127.0.0.1 like:

   user@tux ~ # iptables -t nat -A PREROUTING [ -s 192.168.56.101 ] -d 192.168.56.100 -i vboxnet0 -p tcp -m tcp --dports 1080,9050 -j DNAT --to-destination 127.0.0.1
   user@tux ~ # sysctl -w net.ipv4.conf.vboxnet0.route_localnet=0 (runtime)
   # or 
   user@tux ~ # sysctl -p /etc/sysctl.d/15-route_localnet.conf
   #
   net.ipv4.conf.vboxnet0.route_localnet = 1 (better)
   net.ipv4.conf.all.route_localnet = 1 (dangerous)
   

   By default, kernel refuses to route from source or to destination loopback addresses (i.e. 127.0.0.1). vboxnet0 interface would not be created before VirtualBox launches. So 15-route_localnet.conf does not apply accross boot.

   A more general method is enabling net.ipv4.ip_forward:

   user@tux ~ # sysctl -w net.ipv4.ip_forward=1
   user@tux ~ # iptables -A FORWARD -i vboxnet0 -o vboxnet0 -j ACCEPT
   

5. On MacOS, the vboxnet0 interface is not created automatically, we need to create manually like that of Android-x86 above.

6. IF the host OS or the guest OS is Windows system, then Host-only refuses connection.

   Either turn on network discovery' or use security policy *secpol.msc to set Unidentified network as Private.

IDE Drive Port Limit

Windows XP --port 2 --device 0 refuses to attach extra ISO:

VBoxManage: error: No drive attached to device slot 0 on port 2 of controller 'IDE Controller'

Windows XP guest uses IDE PIIX4 disk drive that supports at most 2 ports. Each port supports two devices , namely (0, 0), (0, 1), (1, 0) and (1, 1). If you have a strong reason to use port 2, then create SATA disk drive like Win 7 guest.

Especially, each port of SATA disk drive only supports one device, namely (0, 0), (1, 0), (2, 0) etc.

Delete VM

user@tux ~ $ vboxmanage list vms
user@tux ~ $ vboxmanage unregistervm WinXP32 --delete

Amost everything related to the VM is deleted, especially the virtual disk image file (.vdi), snapshots, saved state files, VM xml file etc.

Windows Embedded Standard 7 x86 VM

~ $ VBoxManage list ostypes (Windows7)
~ $ VBoxManage createvm --name WES7x86 --ostype Windows7 --register --basefolder ~/Documents/VirtualBox/Machines
~ $ VBoxManage registervm ~/Documents/VirtualBox/Machines/WES7x86/WES7x86.vbox (opt)
~ $ VBoxManage modifyvm WES7x86 --memory 700 --audio alsa --audiocontroller hda --acpi on --vrde on --vrdeproperty "TCP/Ports=5001,5010-5012" --vrdeproperty "TCP/Address=127.0.0.1" --clipboard bidirectional (--draganddrop bidirectional --usb on --usbehci on, --nic1 bridged --bridgeadapter1 wlp3s0, --nic1 nat, --boot1 dvd --boot2 disk --boot3 none --boot4 none)
~ $ VBoxManage createmedium --filename ~/Documents/VirtualBox/Machines/WES7x86/WES7x86.vdi --size 7000 (createhd)
~ $ VBoxManage storagectl WES7x86 --name "SATA Controller" --add sata --controller IntelAHCI --portcount 3 (SATA and Intel AHCI)
~ $ VBoxManage storageattach WES7x86 --storagectl "SATA Controller" --port 0 --device 0 --type hdd --medium ~/Documents/VirtualBox/Machines/WES7x86/WES7x86.vdi
~ $ VBoxManage storageattach WES7x86 --storagectl "SATA Controller" --port 1 --device 0 --type dvddrive --medium /media/Misc/WLshare/en_windows_embedded_standard_7_runtime_x86_dvd_521803.iso
~ $ VBoxManage storageattach WES7x86 --storagectl "SATA Controller" --port 2 --device 0 --type dvddrive --medium /usr/share/virtualbox/VBoxGuestAdditions.iso
~ $ VBoxManage sharedfolder add WES7x86 --name WLshare --hostpath /media/Misc/WLshare
# Installation processing ...
~ $ VBoxManage storageattach WES7x86 --storagectl "SATA Controller" --port 1 --device 0 --type dvddrive --medium emptydrive
~ $ VBoxManage storageattach WES7x86 --storagectl "SATA Controller" --port 2 --device 0 --type dvddrive --medium none

For details on choosing template and components during installation, read the Windows post.

Since the ISO image is till attached to SATA Controller, booting will be directed to installation process again. Either update VM boot order or F12 at early phase.

There is no sound in WES7x86 guest. Please change --audiocontroller to Intel hda instead of default ac97.

Android-x86 VM

~ $ VBoxManage createvm --name Android51 --ostype Linux26 --register --basefolder /media/Misc/VirtualBox/Machines
~ $ VBoxManage modifyvm Android51 --memory 700 --acpi on --mouse usbtablet --usb on --usbehci on --vrde on --vrdeproperty "TCP/Ports=5001,5010-5012" --vrdeproperty "TCP/Address=127.0.0.1" --clipboard bidirectional
~ $ VBoxManage createmedium --filename /media/Misc/VirtualBox/Machines/Android51/Android51.vdi --size 4000
~ $ VBoxManage storagectl Android51  --name "IDE Controller" --add ide --controller PIIX4
~ $ VBoxManage storageattach Android51 --storagectl "IDE Controller" --port 0 --device 0 --type hdd --medium /media/Misc/VirtualBox/Machines/Android51/Android51.vdi
~ $ VBoxManage storageattach Android51 --storagectl "IDE Controller" --port 1 --device 0 --type dvddrive --medium ~/Downloads/cm-x86-13.0-r1.iso
~ $ VBoxManage list vms

1. Installation - Install Android-x86 to harddisk.
2. Create/Modify partitions.
3. Do you want to use GPT? No!
4. New - Primary - Bootable - Write - yes - Quit.
5. sda1 unkown VBOX HARDDISK.
6. ext3/ext4.
7. Format sda1 to ext4? Yes.
8. Do you want to install boot loader GRUB? Yes.
9. Do you want to install /system directory as read-write? Yes.
10. Run Android-x86.

If you choose GPT at 3rd step, then install EFI and GRUB2 instead of GRUB.

First boot takes several minutes to initialize system preparation.

Arch Linux x86_64 VM

~ $ VBoxManage list ostypes (ArchLinux_64)
~ $ VBoxManage createvm --name archlinux_64 --ostype ArchLinux_64 --register --basefolder /media/Misc/VirtualBox/Machines
~ $ VBoxManage modifyvm archlinux_64 --memory 512 --acpi on --vrde on --vrdeproperty "TCP/Ports=5001,5010-5012" --vrdeproperty "TCP/Address=127.0.0.1" --clipboard bidirectional
~ $ VBoxManage createmedium --filename /media/Misc/VirtualBox/Machines/archlinux_64/archlinux_64.vdi --size 4000
~ $ VBoxManage modifymedium /media/Misc/VirtualBox/Machines/archlinux_64/archlinux_64.vdi --resize 5000
~ $ VBoxManage storagectl archlinux_64 --name "SATA Controller" --add sata --controller IntelAHCI --portcount 3
~ $ VBoxManage storageattach archlinux_64 --storagectl "SATA Controller" --port 0 --device 0 --type hdd --medium /media/Misc/VirtualBox/Machines/archlinux_64/archlinux_64.vdi
~ $ VBoxManage storageattach archlinux_64 --storagectl "SATA Controller" --port 1 --device 0 --type dvddrive --medium ~/Downloads/archlinux-2017.11.01-x86_64.iso
~ $ VBoxManage sharedfolder add archlinux_64 --name WLshare --hostpath /media/Misc/WLshare
# starvm
~ $ VBoxManage startvm archlinux_64 --type headless

1. The VDI file is resized after creation.

   Then follow the Arch Linux post.

2. VBoxGuestAdditions in Linux guest requires extra effors. Details refer to Arch Linux post.

VirtualBox GuestAdditions

VirtualBox GuestAdditions consists of device drivers and system applications that optimize the guest operating system for better performance and usability.

1. Some Linux guest OSes (i.e. Gentoo, Arch Linux) already come with all or part of the VirtualBox GuestAdditions.

   Just install the corresponding package. For example:

   [root@host ~]# emerge -avt app-emulation/virtualbox-guest-additions # Gentoo
   [root@host ~]# pacman -S virtualbox-guest-utils/virtualbox-guest-utils-nox # archlinux
   

   This method is always preferred!

2. Alternatively, we can mount the ISO of GuestAdditions and invoke the relevant installation script manually.

   Firstly, make sure development tools like gcc, make, kernel-headers, kernel-devel etc. are present on guest OS. Also confirm the guest OS kernel version matches that of package kernel-headers and package kernel-devel.

   Then, we can obtain the ISO from host by vboxmanage storageattach.

   [root@host ~]# lsblk -f
   

   We can also get ISO file from guest OS (Arch Linux) package repository:

   [root@host ~]# pacman -S virtualbox-guest-iso
   [root@host ~]# ls /usr/lib/virtualbox/additions/VBoxGuestAdditions.iso
   

   Another method, is to download the ISO from VirtualBox official website. Whatever methods you choose to get the ISO, make sure it has the same version as VirtualBox VMM on host OS.

   Once the ISO is obtained, we mount the ISO:

   [root@host ~]# ll /dev/cdrom
   [root@host ~]# mkdir -p /mnt/vbox
   [root@host ~]# mount -o loop /dev/cdrom /mnt/vbox
   [root@host ~]# ll /mnt/vbox
   

   Lastly, install GuestAdditions:

   [root@host ~]# sh /mnt/vbox/VBoxLinuxAdditions.run
   

   Restart guest OS before VirtualBox guest additions take effect.

3. A real pactice on Arch guest

   1. Gentoo host: kernel-4.12.5, VirtualBox 5.1.26.
   2. Arch guest: kernel-4.13.12, VirtualBox 5.2.2.

   Gentoo is relatively conservative on package rolling update compared to Arch Linux. So installing GuestAdditions directly from Arch repository is beffer.

   [root@host ~]# pacman -S virtualbox-guest-utils (X Window)
   # or
   [root@host ~]# pacman -S virtualbox-guest-utils-nox (no X)
   

   Enable vboxservice unit service to load vboxguest, vboxsf, and vboxvideo kernel modules.

   [root@host ~]# systemctl enable vboxservice
   

   VBoxClient (or the VBoxClient-all wrapper) is another unit service from the GuestAdditions. It manages clipboard, seamless window display, etc. The associated /etc/xdg/autostart/vboxclient.desktop launches VBoxClient-all on logon. VBoxClient-all script launches VBoxClient as:

   [user@host ~]$ VBoxClient --clipboard --draganddrop --seamless --display --checkhostversion
   

   Check Autostart section above on how to launch VBoxclient alongside with awesome.

VirtualBox sharedfolder

Make sure vboxservice is enabled and started.

Add shared folder:

user@host ~ $ VBoxManage sharedfolder add archlinux --name share_name --hostpath /path/to/host/folder [--automount]

Arch Linux guest can mount the shared folder manually (mount -t vboxsf), automatically (vboxmanage --automount), or by fstab. If --automount provided, then by default, the folder is mounted for root:vboxsf. For other accounts to read and write, do usermod -aG vboxsf <username>.

Alternatively, use fstab to flexibly control mount options:

# /etc/fstab

wlshare        /media/wlshare        vboxsf        nodev,nosuid,noexec,uid=root,gid=vboxsf,rw,iocharset=utf8,dmode=0770,fmode=0660        0 0

wlshare        /media/wlshare        vboxsf        nodev,nosuid,noexec,noauto,uid=root,gid=vboxsf,rw,iocharset=utf8,dmode=0770,fmode=0660,x-systemd.automount        0 0

1. The noauto option is to avoid service racing on booting. For example, GuestAdditions are not loaded yet while fstab tries to mount it.
2. The x-systemd.automount will create media-wlshare unit upon systemctl daemon-reload.
3. Only root is allowed to mount vboxsf device. So the user option is not permissible.
4. Read Why nodev,nosuid,noexe are important?.

Expand VDI Size

Occasionally, the guest OS warns running out of disk space when you should resize the VM disk and parition thereof.

1. Firstly, make sure the guest does not have snapshots. If there exist any, delete all of them.
2. Resizing does not work if the guest VM resides on fix-sized VDI.
3. Currently, only expansion is supported. You cannot decrease any VDI or partitions.

Here, I will show an example of expanding archlinux_64 VM above. On the host:

user@tux ~ $ VBoxManage list hdds
user@tux ~ $ VBoxManage modifymedium /media/Misc/VirtualBox/Machines/archlinux_64/archlinux_64.vdi --resize 10000
user@tux ~ $ VBoxManage list hdds

The VDI is increasing from 5GiB to 10GiB. Next, we should let the VM known the expansion. Basically, we attach to the VM a live booting media containing parted or gparted tool. GParted live CD and Arch Linux ISO are such examples. On the host:

user@tux ~ $ VBoxManage showvminfo archlinux_64
user@tux ~ $ VBoxManage storageattach archlinux_64 --storagectl "SATA Controller" --port 1 --device 0 --type dvddrive --medium ~/Downloads/archlinux-2018.01.01-x86_64.iso
user@tux ~ $ VBoxManage showvminfo archlinux_64

Please make sure boot the VM on the attached ISO instead of VDI. In the live system, suppose /dev/sda represents VDI:

[root@archiso / #] fdisk/blkid/lsblk/findmnt
[root@archiso / #] parted -a optimal /dev/sda
(parted) help
(parted) print free
The backup GPT table is not at the end of the disk, as it should be. This might mean that another operating system believes the disk is smaller. Fix, by moving the backup to the end (and removing the old backup)? Fix/Ignore/Cancel?
(parted) Fix
(parted) print free
(parted) resizepart 1 100%

parted detects the VDI expanded and reminds Fix. The key is resizepart (or resize depending on parted version) epxanding (100%) the root partition to include newly added space. That's all!

1. Some posts write resizepart can be done on guest OS directly as long as swap partition/file is turned off.
2. For Windows guest, use enclosed disk management to finish the job.

CentOS 8.2 Amd64

This section describes procedures to manage CentOS 8.2 VM:

1. Start the VM.

   Enable the Host-only interface /etc/sysconfig/network-scripts/ifcfg-enp0s8.

2. Start the VM in headless mode either on command line or by GUI.

   SSH into the VM.

3. Configure repository mirror.

   dnf group install 'Development Tools'.

4. Insert GuestAdditions CD; mount sr0; install GuestAdditions.

   1. Add shared folder.
   2. Add clipboard.

References

1. gentoo wiki
2. install_virtualbox_in_gentoo
3. createVBoxVM.sh
4. how-to-attach-a-virtual-hard-disk-using-vboxmanage
5. Remote virtual machines
6. headless vm
7. guestadditions in headless
8. vbox create headless vm
9. VBoxManage createvm manully