Linux is equipped with KVM, which is another hypervisor at the same level of VMWare and VirtualBox. However, it has the great capability for GPU pass through, which grant the guest system to access GPU natively.

The function is great, but the setup is a bit complicated because it involves low level configuration of Linux to mask the GPU away from kernel, which allow the guest to use it exclusively.

To do so, we need to do the following steps.
1. Install the KVM as followed

sudo apt-get install qemu-kvm libvirt-bin virtinst bridge-utils cpu-checker virt-manager ovmf

2. Rebuild the initramfs for the kernel, so that it can load before proper Radeon or AMDGPU load.

jimmy@jimmy-home:~$ cat /etc/modules
# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.
pci_stub
vfio
vfio_iommu_type1
vfio_pci
vfio_virqfd
jimmy@jimmy-home:~$ 

jimmy@jimmy-home:~$ cat /etc/initramfs-tools/modules 
# List of modules that you want to include in your initramfs.
# They will be loaded at boot time in the order below.
#
# Syntax:  module_name [args ...]
#
# You must run update-initramfs(8) to effect this change.
#
# Examples:
#
# raid1
# sd_mod
pci_stub ids=1002:683d,1002:aab0
vfio
vfio_iommu_type1
vfio_pci
vfio_virqfd 
jimmy@jimmy-home:~$ 
jimmy@jimmy-home:~$ sudo update-initramfs -u

3. Config the kernel to load vfio-pci before loading any GPU driver, also blacklist the GPU hardware ID which look up in “lspci -nnk”. Furthermore, you can verify the status with “lspci -nnk” make sure the driver for GPU is vfio-pci rather than radeon

jimmy@jimmy-home:~$ vi /etc/modprobe.d/vfio.conf 
softdep radeon pre: vfio-pci
softdep amdgpu pre: vfio-pci
options vfio-pci ids=1002:683d,1002:aab0 disable_vga=1

01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Cape Verde XT [Radeon HD 7770/8760 / R7 250X] [1002:683d]
	Subsystem: PC Partner Limited / Sapphire Technology Cape Verde XT [Radeon HD 7770/8760 / R7 250X] [174b:e244]
	Kernel driver in use: vfio-pci
	Kernel modules: radeon, amdgpu
01:00.1 Audio device [0403]: Advanced Micro Devices, Inc. [AMD/ATI] Cape Verde/Pitcairn HDMI Audio [Radeon HD 7700/7800 Series] [1002:aab0]
	Subsystem: PC Partner Limited / Sapphire Technology Cape Verde/Pitcairn HDMI Audio [Radeon HD 7700/7800 Series] [174b:aab0]
	Kernel driver in use: vfio-pci
	Kernel modules: snd_hda_intel

4. It is not a good practice to run libvirtd with root, but it is a quick way to let libvirtd to access an attachable storage.

Changing /etc/libvirt/qemu.conf to make things work.
Uncomment user/group to work as root.
Then restart libvirtd

The following are the reference I checked

https://bbs.archlinux.org/viewtopic.php?id=162768
https://wiki.archlinux.org/index.php/PCI_passthrough_via_OVMF#Using_vfio-pci
https://pve.proxmox.com/wiki/Pci_passthrough
https://ycnrg.org/vga-passthrough-with-ovmf-vfio/

First, install the Multi Disk Admin tools

sudo apt-get install initramfs-tools mdadm 

Next, set the Partition Type to “fd Linux raid auto”

sudo fdisk /dev/sdb
sudo fdisk /dev/sdc

Create the MD(md0)

sudo mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1

Format the partition with Ext4

sudo mkfs.ext4 /dev/md0

Command to check RAID status

sudo mdadm --query /dev/md0
sudo mdadm --detail /dev/md0

I am playing around JHipster recently, one of the goal for it is the Micro services architecture.

Under such assumption, a reverse proxy is inevitable. Apart from HAProxy, I try to use Nginx as the reverse proxy. Here is the config I use.

##
# You should look at the following URL's in order to grasp a solid understanding
# of Nginx configuration files in order to fully unleash the power of Nginx.
# http://wiki.nginx.org/Pitfalls
# http://wiki.nginx.org/QuickStart
# http://wiki.nginx.org/Configuration
#
# Generally, you will want to move this file somewhere, and start with a clean
# file but keep this around for reference. Or just disable in sites-enabled.
#
# Please see /usr/share/doc/nginx-doc/examples/ for more detailed examples.
##

#### JHipster SPECIFIC ROUTE ####
upstream jhipster {
	server localhost:8080 weight=10 max_fails=3 fail_timeout=30s;
	server localhost:18080 weight=10 max_fails=3 fail_timeout=30s;
	server localhost:28080 weight=10 max_fails=3 fail_timeout=30s;
}
#### JHipster SPECIFIC ROUTE ####

# Default server configuration
#
server {
	listen 80 default_server;
	listen [::]:80 default_server;

	# SSL configuration
	#
	# listen 443 ssl default_server;
	# listen [::]:443 ssl default_server;
	#
	# Note: You should disable gzip for SSL traffic.
	# See: https://bugs.debian.org/773332
	#
	# Read up on ssl_ciphers to ensure a secure configuration.
	# See: https://bugs.debian.org/765782
	#
	# Self signed certs generated by the ssl-cert package
	# Don't use them in a production server!
	#
	# include snippets/snakeoil.conf;

	root /var/www/html;

	# Add index.php to the list if you are using PHP
	index index.html index.htm index.nginx-debian.html;

	server_name _;

#	location / {
#		# First attempt to serve request as file, then
#		# as directory, then fall back to displaying a 404.
#		try_files $uri $uri/ =404;
#	}

	location / {  
		proxy_pass http://jhipster;  
		proxy_http_version 1.1;  
		proxy_set_header Host $host;  
		proxy_set_header Upgrade $http_upgrade;  
		proxy_set_header Connection 'upgrade';  
		proxy_set_header X-Real-IP $remote_addr;
        	proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
	        proxy_set_header X-Forwarded-Proto $scheme;
		proxy_cache_bypass $http_upgrade;  
	}

	# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
	#
	#location ~ \.php$ {
	#	include snippets/fastcgi-php.conf;
	#
	#	# With php7.0-cgi alone:
	#	fastcgi_pass 127.0.0.1:9000;
	#	# With php7.0-fpm:
	#	fastcgi_pass unix:/run/php/php7.0-fpm.sock;
	#}

	# deny access to .htaccess files, if Apache's document root
	# concurs with nginx's one
	#
	#location ~ /\.ht {
	#	deny all;
	#}
}


# Virtual Host configuration for example.com
#
# You can move that to a different file under sites-available/ and symlink that
# to sites-enabled/ to enable it.
#
#server {
#	listen 80;
#	listen [::]:80;
#
#	server_name example.com;
#
#	root /var/www/example.com;
#	index index.html;
#
#	location / {
#		try_files $uri $uri/ =404;
#	}
#}

I have recently get a bad experience on blowing up my home Ubuntu desktop by adding jimmy as the user again. Jimmy is no longer belongs to the sudoer group and I fail to add anyone back to the sudoer group. I need to use the linux single user mode / recovery mode to get back my account.

The sequence is as followed.

1. In GRUB, select recovery
2. I will be prompted with a root shell. However, the root FS is just mount as read only.

mount -o rw,remount /

3. Add back sudoer to jimmy

useradd jimmy -G sudo