How to run Android in Virtualbox on Linux?
I was able to install Android-x86 on my Debian 9 box with no real problem.   Following are my system details, the articles I followed, commands I used and lastly the settings info of the VM itself. 

System:


Chassis: desktop
Desktop Environment: Gnome 3.22.2
Operating System: Debian GNU/Linux 9.1 (stretch)
Kernel: Linux 4.9.0-3-amd64
Architecture: x86-64
Processor: Intel Core i5-4570S CPU @ 2.90GHz × 4
Processor supports HW virtualization: yes   
Processor supports PAE: yes   
Processor supports long mode: yes
Processor supports nested paging: yes
Memory: 15.4 GiB   Graphics: Intel® Haswell Desktop
Disk: 1.1 TB


First I installed VirtualBox 5.1:


$ cd /etc/apt/sources.list.d
$ sudo touch virtualbox.list
$ sudo nano virtualbox.list


In nano I typed:
 deb http://download.virtualbox.org/virtualbox/debian stretch contrib

Then to save and exit nano editor:

ctrl+o
ctrl+x

Then to get keys, update repos and install VB.

$ cd ~/Keys
$ curl -O https://www.virtualbox.org/download/oracle_vbox_2016.asc
$ sudo apt-key add oracle_vbox_2016.asc
$ sudo apt-get update
$ sudo apt-get install virtualbox-5.1


Then I set about installing Android-x86:

First I downloaded Android-x86 6.0-r3 (the third stable release of marshmallow-x86) from here. Then I followed this article: "How to Install Android in VirtualBox"
by Cameron Summerson, dated June 29th, 2017.  The only snag I ran into was for mouse support.

The suggestion here didn't work for me but it might work for someone else.

So then I tried the discussion here which instructed to turn off VM which in my case is  "Android" and try the command:

$ VBoxManage modifyvm Android --mouse ps2

After turning Android VM back on, I had mouse support.

These are the VM's settings info as retrieved by CLI command:


$ VBoxManage showvminfo Android --details


Name:            Android
Groups:          /
Guest OS:        Linux 2.6 / 3.x / 4.x (64-bit)
UUID:            a8a28a18-2d9a-4aff-872c-890d72ec9e8f
Config file:     /home/shine/VirtualBox VMs/Android/Android.vbox
Snapshot folder: /home/shine/VirtualBox VMs/Android/Snapshots
Log folder:      /home/shine/VirtualBox VMs/Android/Logs
Hardware UUID:   a8a28a18-2d9a-4aff-872c-890d72ec9e8f
Memory size:     6020MB
Page Fusion:     off
VRAM size:       48MB
CPU exec cap:    100%
HPET:            off
Chipset:         piix3
Firmware:        BIOS
Number of CPUs:  4
PAE:             off
Long Mode:       on
Triple Fault Reset: off
APIC:            on
X2APIC:          on
CPUID Portability Level: 0
CPUID overrides: None
Boot menu mode:  message and menu
Boot Device (1): Floppy
Boot Device (2): DVD
Boot Device (3): HardDisk
Boot Device (4): Not Assigned
ACPI:            on
IOAPIC:          on
BIOS APIC mode:  APIC
Time offset:     0ms
RTC:             UTC
Hardw. virt.ext: on
Nested Paging:   on
Large Pages:     off
VT-x VPID:       on
VT-x unr. exec.: on
Paravirt. Provider: Default
Effective Paravirt. Provider: KVM
State:           running (since 2017-08-04T02:01:58.782000000)
Monitor count:   1
3D Acceleration: on
2D Video Acceleration: off
Teleporter Enabled: off
Teleporter Port: 0
Teleporter Address: 
Teleporter Password: 
Tracing Enabled: off
Allow Tracing to Access VM: off
Tracing Configuration: 
Autostart Enabled: off
Autostart Delay: 0
Default Frontend: 
Storage Controller Name (0):            IDE
Storage Controller Type (0):            PIIX4
Storage Controller Instance Number (0): 0
Storage Controller Max Port Count (0):  2
Storage Controller Port Count (0):      2
Storage Controller Bootable (0):        on
Storage Controller Name (1):            SATA
Storage Controller Type (1):            IntelAhci
Storage Controller Instance Number (1): 0
Storage Controller Max Port Count (1):  30
Storage Controller Port Count (1):      1
Storage Controller Bootable (1):        on
IDE (1, 0): Empty
SATA (0, 0): /home/shine/VirtualBox VMs/Android/Android.vdi (UUID: a111cb34-b24f-4b38-ac32-bc33428f8b55)
NIC 1:           MAC: 080027D5FAC2, Attachment: NAT, Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none
NIC 1 Settings:  MTU: 0, Socket (send: 64, receive: 64), TCP Window (send:64, receive: 64)
NIC 2:           disabled
NIC 3:           disabled
NIC 4:           disabled
NIC 5:           disabled
NIC 6:           disabled
NIC 7:           disabled
NIC 8:           disabled
Pointing Device: PS/2 Mouse
Keyboard Device: PS/2 Keyboard
UART 1:          disabled
UART 2:          disabled
UART 3:          disabled
UART 4:          disabled
LPT 1:           disabled
LPT 2:           disabled
Audio:           enabled (Driver: PulseAudio, Controller: AC97, Codec: AD1980)
Clipboard Mode:  disabled
Drag and drop Mode: disabled
Session name:    GUI/Qt
Video mode:      1024x768x32 at 0,0 enabled
VRDE:            disabled
USB:             enabled
EHCI:            disabled
XHCI:            disabled
USB Device Filters:

Available remote USB devices:

Currently Attached USB Devices:

Bandwidth groups:  
Shared folders:  
Name: 'shine', Host path: '/home/shine' (machine mapping), writable
VRDE Connection:    not active
Clients so far:     0
Video capturing:    not active
Capture screens:    0
Capture file:       /home/shine/VirtualBox VMs/Android/Android.webm
Capture dimensions: 1024x768
Capture rate:       512 kbps
Capture FPS:        25
Guest:
Configured memory balloon size:      0 MB
OS type:                             Linux26_64
Additions run level:                 0
Guest Facilities:
No active facilities.