Tag Archives: Arch Linux

KVM with vga passthrough in arch linux

I’ve once again switched from Proxmox to Arch Linux for my desktop machine. Both use KVM so it’s really just a matter of using the different VM manager syntax (virt-manager vs qm.) I used my notes from my previous stint with Arch, my article on GPU Passthrough in Proxmox as well as a thorough reading of the Arch wiki’s PCI Passthrough article.

Enable IOMMU

Configure GRUB to load the necessary iommu modules at boot. Append amd_iommu=on iommu=pt to the end of GRUB_CMDLINE_LINUX_DEFAULT (change accordingly if you have Intel instead of AMD)

sudo vim /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="loglevel=3 amd_iommu=on iommu=pt"

Run update-grub

sudo update-grub

Reserve GPU for VFIO

Reserve the GPU you wish to pass through to a VM for use with the vfio kernel driver (so the host OS doesn’t interfere with it)

  1. Determine the PCI address of your GPU
    1. Run lspci -v and look for your card. Mine was 01:00.0 & 01:00.1. You can omit the part after the decimal to include them both in one go – so in that case it would be 01:00
    2. Run lspci -n -s <PCI address from above> to obtain vendor IDs.
      Example :
      lspci -n -s 01:00
      01:00.0 0300: 10de:1b81 (rev a1)
      01:00.1 0403: 10de:10f0 (rev a1)
  2. Assign your GPU to vfio driver using the IDs obtained above.
    Example using above IDs:
    echo "options vfio-pci ids=10de:1b81,10de:10f0" >> /etc/modprobe.d/vfio.conf

Reboot the host to put the kernel / drivers into effect.

Configure virt-manager

Install virt-manager, dnsmasq & libvirtd:

pacman -Sy libvirtd virt-manager dnsmasq
sudo systemctl enable libvirtd
sudo systemctl start libvirtd

Configure Networking

Assuming you’re using network manager for your connections, create a bridge (thanks to ciberciti.biz & the arch wiki for information on how to do so.) Replace interface names with ones corresponding to your machine:

sudo nmcli connection add type bridge ifname br0 stp no
sudo nmcli connection add type bridge-slave ifname enp4s0 master br0 
sudo nmcli connection show
#Make note of the active connection name
sudo nmcli connection down "Wired connection 2" #from above
sudo nmcli connection up bridge-br

Create a second bridge bound to lo0 for host-only communication. Change IP as desired:

sudo nmcli connection add type bridge ifname br99 stp no ip4
sudo nmcli connection add type bridge-slave ifname lo master br99 
sudo nmcli connection up bridge-br99

Configure VM

Initial configuration

When creating the passthrough VM, make sure chipset is Q35.

Set the CPU model to host-passthrough (type it in, there is no dropdown for it.)

When adding disks / other devices, set the device model to virtio

Add your GPU by going to Add Hardware and finding it under PCI Host Device.

Windows 10 specific tweaks

If your passthrough VM is going to be windows based, some tweaks are required to get the GPU to work properly within the VM.

Ignore MSRs (blue screen fix)

Later versions of Windows 10 instantly bluescreen with kmode_exception_not_handled unless you pass an option to ignore MSRs. Add the kvm ignore_msrs=1 option in /etc/modprobe.d/kvm.conf to do so. Optionally add the report_ignored_msrs=0 option to squelch massive amounts of kernel messages every time an MSR was ignored.

echo "options kvm ignore_msrs=1" >> /etc/modprobe.d/kvm.conf
#Optional - ignore kernel messages from ignored MSRs
echo "options kvm report_ignored_msrs=0" >> /etc/modprobe.d/kvm.conf

Reboot to make those changes take effect.

NVIDIA Code 43 workaround

Use the virsh edit command to make some tweaks to the VM configuration. We need to hide the fact that this is a VM otherwise the GPU drivers will not load and will throw Error 43. We need to add a vendor_id in the hyperv section, and create a kvm section enabling hidden state, which hides certain CPU flags that the drivers use to detect if they’re in a VM or not.

sudo virsh edit <VM_NAME>

		<vendor_id state='on' value='1234567890ab'/>
	<hidden state='on'/>

Optimize CPU

If you operate on a multi-core system such as my AMD Ryzen Threadripper the you will want to optimize your CPU core configuration in the VM per the CPU Pinning section in the Arch Wiki

Determine your CPU topology by running lscpu -e. The important things to look for are the CPU number and core number. On my box, it looks like this:

0 0 0 0 0:0:0:0 yes 3400.0000 2200.0000
1 0 0 1 1:1:1:0 yes 3400.0000 2200.0000
2 0 0 2 2:2:2:0 yes 3400.0000 2200.0000
3 0 0 3 3:3:3:0 yes 3400.0000 2200.0000
4 0 0 4 4:4:4:1 yes 3400.0000 2200.0000
5 0 0 5 5:5:5:1 yes 3400.0000 2200.0000
6 0 0 6 6:6:6:1 yes 3400.0000 2200.0000
7 0 0 7 7:7:7:1 yes 3400.0000 2200.0000
8 0 0 8 8:8:8:2 yes 3400.0000 2200.0000
9 0 0 9 9:9:9:2 yes 3400.0000 2200.0000
10 0 0 10 10:10:10:2 yes 3400.0000 2200.0000
11 0 0 11 11:11:11:2 yes 3400.0000 2200.0000
12 0 0 12 12:12:12:3 yes 3400.0000 2200.0000
13 0 0 13 13:13:13:3 yes 3400.0000 2200.0000
14 0 0 14 14:14:14:3 yes 3400.0000 2200.0000
15 0 0 15 15:15:15:3 yes 3400.0000 2200.0000
16 0 0 0 0:0:0:0 yes 3400.0000 2200.0000
17 0 0 1 1:1:1:0 yes 3400.0000 2200.0000
18 0 0 2 2:2:2:0 yes 3400.0000 2200.0000
19 0 0 3 3:3:3:0 yes 3400.0000 2200.0000
20 0 0 4 4:4:4:1 yes 3400.0000 2200.0000
21 0 0 5 5:5:5:1 yes 3400.0000 2200.0000
22 0 0 6 6:6:6:1 yes 3400.0000 2200.0000
23 0 0 7 7:7:7:1 yes 3400.0000 2200.0000
24 0 0 8 8:8:8:2 yes 3400.0000 2200.0000
25 0 0 9 9:9:9:2 yes 3400.0000 2200.0000
26 0 0 10 10:10:10:2 yes 3400.0000 2200.0000
27 0 0 11 11:11:11:2 yes 3400.0000 2200.0000
28 0 0 12 12:12:12:3 yes 3400.0000 2200.0000
29 0 0 13 13:13:13:3 yes 3400.0000 2200.0000
30 0 0 14 14:14:14:3 yes 3400.0000 2200.0000
31 0 0 15 15:15:15:3 yes 3400.0000 2200.0000

From the above output I see my CPU core 0 is shared by CPUs 0 & 16, meaning CPU 0 and CPU 16 (as seen by the Linux kernel) are hyperthreaded to the same physical CPU core.

Especially for gaming, you want to keep all threads on the same CPU cores (for multithreading) and the same CPU die (on my threadripper, CPUs 0-7 reside on one physical die, and CPUs 8-15 reside on the other, within the same socket.)

In my case I want to dedicate one CPU die to my VM with its accompanying hyperthreads (CPUs 0-7 & hyperthreads 16-23) You can accomplish this using the virsh edit command and creating a cputune section (make sure you have a matching vcpu count for the number of cores you’re configuring.) Also edit CPU mode with the proper topology of 1 socket, 1 die, 8 cores with 2 threads.

sudo virsh edit <VM_NAME>

<domain type='kvm'>
  <vcpu placement='static'>16</vcpu>  
    <vcpupin vcpu='0' cpuset='0'/>
    <vcpupin vcpu='1' cpuset='16'/>
    <vcpupin vcpu='2' cpuset='1'/>
    <vcpupin vcpu='3' cpuset='17'/>
    <vcpupin vcpu='4' cpuset='2'/>
    <vcpupin vcpu='5' cpuset='18'/>
    <vcpupin vcpu='6' cpuset='3'/>
    <vcpupin vcpu='7' cpuset='19'/>
    <vcpupin vcpu='8' cpuset='4'/>
    <vcpupin vcpu='9' cpuset='20'/>
    <vcpupin vcpu='10' cpuset='5'/>
    <vcpupin vcpu='11' cpuset='21'/>
    <vcpupin vcpu='12' cpuset='6'/>
    <vcpupin vcpu='13' cpuset='22'/>
    <vcpupin vcpu='14' cpuset='7'/>
    <vcpupin vcpu='15' cpuset='23'/>
  <cpu mode='host-passthrough' check='none'>
    <topology sockets='1' dies='1' cores='8' threads='2'/>

I found here I’ve been doing the vcpupins wrong – apparently the better way to do it is to do primary CPU thread, then hyperthread CPU. I had been doing all the main CPUs first, then their hyperthreads. Once I change to the every-other configuration stuttering disappeared.

Update 6/28/20: Additional tuning since I was having some stuttering and framerate issues

Dedicate CPUs to the VM (host will not use them) – append isolcups, nohzZ_full & rcu_nocbs kernel parameters into /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT=... isolcpus=0-7,16-23 nohz_full=0-7,16-23 rcu_nocbs=0-7,16-23

Update grub:

sudo grub-mkconfig -o /boot/grub/grub.cfg

Reboot, then check if it worked:

cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-linux root=/dev/mapper/arch-root rw loglevel=3 amd_iommu=on iommu=pt isolcpus=0-7,16-23 nohz_full=0-7,16-23 rcu_nocbs=0-7,16-23
taskset -cp 1
pid 1's current affinity list: 8-15,24-31

You can still tell programs to use the CPUs the VM has manually with the taskset command:

chrt -r 1 taskset -c <cores to use> <name of program/process>

Change CPU frequency setting to use performance mode:

sudo pacman -S cpupower
sudo cpupower frequency-set -g performance


I’m very pleased with my current setup. It works well!

arch install notes 2020-06

My install notes to get Arch Linux set up just the way I like it, June 2020 edition. Reference: https://wiki.archlinux.org/index.php/Installation_guide

Change to dvorak layout:
loadkeys dvorak

Sync NTP time:
timedatectl set-ntp true

Configure disk:
#create separate efi partition, LVM root & swap
pvcreate <dev>
vgcreate arch <dev>
lvcreate -L+2G arch -n swap
lvcreate -l100%FREE -n root arch

Initialize swap:
mkswap /dev/arch/swap
swapon /dev/arch/swap

Format & Mount root:
mkfs.ext4 /dev/arch/root
mount /dev/arch/root /mnt

Create EFI partition
mkdosfs -F32 <partition 1>
mkdir /mnt/efi
mount <partition 1> /mnt/efi

Make mirrorlist use only xmission
sed -i 's/^Server/#Server/g;s/#Server\(.*xmission.*\)/Server\1/g' /etc/pacman.d/mirrorlist

Install base system plus extra packages:
pacstrap /mnt base linux linux-firmware lvm2 efibootmgr samba vim htop networkmanager inetutils man-db man-pages texinfo openssh grub

Generate fstab
genfstab -U /mnt >> /mnt/etc/fstab

Enter new environment chroot
arch-chroot /mnt

Set timezone
ln -sf /usr/share/zoneinfo/America/Boise /etc/localtime

Configure en_US locales
sed -i 's/^#en_US\(.*\)/en_US\1/g' /etc/locale.gen

Make dvorak layout permanent
echo "KEYMAP=dvorak" > /etc/vconsole.conf

Set hostname
echo "_HOSTNAME_" > /etc/hostname
echo " _HOSTNAME_._DOMAIN_ _HOSTNAME_" >> /etc/hosts

Enable lvm2 hook for initial ramdisk (boot)
sed -i 's/HOOKS=(.*\<block\>/& lvm2/' /etc/mkinitcpio.conf

Generate initial ramdisk
mkinitcpio -P

Set password for root user:

Install Grub (EFI)
grub-install --target=x86_64-efi --efi-directory=/efi --bootloader-id=GRUB
grub-mkconfig -o /boot/grub/grub.cfg

Enable networking & SSH on bootup:
systemctl enable NetworkManager sshd

Exit chroot & reboot

Gaming VM with graphics passthrough in Arch Linux

At one point I had KVM with GPU passthrough running in Arch Linux. I have since moved away from it back to ProxMox. Here are my notes I jotted down when I did this in Arch. Sorry these are just rough notes, I didn’t end up using Arch for long enough to turn this into a polished article.

pacman -Sy qemu netctl ovmf virt-manager

When creating VM, make sure chipset is Q35

CPU model host-passthrough (write it in)

Create VirtIO SCSI controller and attach drives to it

NIC device model: virtio

—- networking —-

Create bridge:


Copy /etc/netctl/examples/bridge to /etc/netctl/bridge

Description="Example Bridge connection"

#Optional - give your system another IP for host-only networking
ExecUpPost="ip addr add dev br0"
sudo netctl reenable bridge
sudo netctl restart bridge

In the VM add another network interface, also assign to br0. Manually specify IP in guest VM to match subnet specified above in ExecUpPost


Allow UEFI bios: https://wiki.archlinux.org/index.php/libvirt#UEFI_Support

sudo vim /etc/libvirt/qemu.conf

nvram = [

sudo systemctl restart libvirtd

Edit VM hardware:

CLI: sudo virsh edit <vm name>

GUI: double click on VM, then click second icon fnom the left (little i bubble)  Add GPU this way

Nvidia GPU: need to do x otherwise code 43

		<vendor_id state='on' value='whatever'/>
	<hidden state='on'/>

Hot add CD:

sudo virsh attach-disk <VM_NAME> <ISO LOCATION>  hdb –type cdrom

Add second NIC: https://jamielinux.com/docs/libvirt-networking-handbook/bridged-network.html

sudo virsh edit win10

<interface type="bridge">
   <source bridge="br1"/>

CPU configuration

Current Allocation 16

Topology / manually set CPU topology

1 socket, 16 cores, 1 thread

<vcpupin vcpu=’0′ cpuset=’16’/>
<vcpupin vcpu=’1′ cpuset=’17’/>
<vcpupin vcpu=’2′ cpuset=’18’/>
<vcpupin vcpu=’3′ cpuset=’19’/>
<vcpupin vcpu=’4′ cpuset=’20’/>
<vcpupin vcpu=’5′ cpuset=’21’/>
<vcpupin vcpu=’6′ cpuset=’22’/>
<vcpupin vcpu=’7′ cpuset=’23’/>
<vcpupin vcpu=’8′ cpuset=’24’/>
<vcpupin vcpu=’9′ cpuset=’25’/>
<vcpupin vcpu=’10’ cpuset=’26’/>
<vcpupin vcpu=’11’ cpuset=’27’/>
<vcpupin vcpu=’12’ cpuset=’28’/>
<vcpupin vcpu=’13’ cpuset=’29’/>
<vcpupin vcpu=’14’ cpuset=’30’/>
<vcpupin vcpu=’15’ cpuset=’31’/>

Running Windows 10 on Linux using KVM with VGA Passthrough



--machine q35 \
--host-device 4b:00.0 --host-device 4b:00.1 \



add usb ports. Doesn’t work if nothing’s in the port?

virsh edit win10

<hostdev mode=’subsystem’ type=’usb’ managed=’yes’>
<address bus=’3′ device=’2’/>
<address type=’usb’ bus=’0′ port=’2’/>

Remove Tablet input device to get 4th USB passthrough option





internal error: Unknown PCI header type '127'


Threadripper PCI Reset bug: https://www.reddit.com/r/Amd/comments/7gp1z7/threadripper_kvm_gpu_passthru_testers_needed/

Error 43:

		<vendor_id state='on' value='whatever'/>
	<hidden state='on'/>

Audio cuts out whenever microphone is used

I had a very odd issue where all sound disappeared in my Windows VM if the microphone was used. Even simply opening up audio properties and going to the Recording tab triggered this issue. Disabling / re-enabled Special Effects for the playback device brought it back until the microphone was accessed again.

I’m using USB sound card passed through to the VM for audio. It stems from the VM’s USB controller. When I had it set to USB3 the issue would occur. When set to USB2 the issue went away. Bizarre.

Fix no sound in Wine

Lately I’ve been doing 100% of my gaming in Linux. The latest versions of wine in Arch Linux have been fantastic (for the most part.) I recently installed a game called Gauntlet (a windows-only steam game.) For some reason I had no sound. Sound worked fine in other Wine games, just not this one.

After much digging I found this post on the Arch Linux forums which fixed my issue. The issue was not having the proper 32bit sound libraries installed. The fix was as simple as:

sudo pacman -Sy lib32-alsa-plugins lib32-libpulse lib32-openal


Heroes of the Storm in Linux with Wine

I’ve been wanting to get some of my games to play properly in Linux with Wine. Recently I’ve been able to get Heroes of the Storm working pretty well in Arch Linux. This is what I did to get it working with my NVIDIA GeForce GTX 1070.

Update 4/22/2017: Even more changes with wine 2.4-staging. This site is very helpful:

For Wine Staging release 2.3 and later

  • Change Windows Version to Windows XP
    • Open Wine configuration (winecfg) and change setting at the bottom
  • Install Visual C++ 2015 libraries (needed to update games)
    • winetricks vcrun2015
  • If you get errors about not being able to connect / login:
  • Install lib32-libldap and lib32-gnutls
Installer login Workaround:
 - Create a clean 32-bit wineprefix
 - Run the Battle.net installer with default options
  * It crashes at the very end when it tries to launch, but installation still finishes and succeeds.
 - Overwrite the default Battle.net config file:
  cd "$WINEPREFIX/users/$(whoami)/Application\ Data/Battle.net/"
  echo "{\"Client\": {\"HardwareAcceleration\": \"false\"}}" > "Battle.net.config"
 - Set the default mimicked windows version to Windows XP
 - Run Battle.net:
  wine "$WINEPREFIX/drive_c/Program\ Files/Battle.net/Battle.net\ Launcher.exe"

Update 3/31/2017: A few things have changed since I wrote this article. I’ll keep the old information for historical purposes, but the process has updated

  1. Install mainstream nvidia drivers
    yaourt -Sy nvidia
  2. Install wine-staging
    pacman -Sy wine-staging
  3. Remove / move existing wine configuration if you have one
    rm -rf ~/.wine
  4. Create new 32bit wine prefix
    WINEARCH=win32 wine wineboot
  5. Enable CSMT by going to the Staging Tab and checking “Enable_CSMT for better graphic performance”
  6. Disable DirectX11 as described in step 3 below

  1. Install beta Nvidia drivers
    1.  yaourt -Sy nvidia-beta
  2. Install wine
    1. pacman -Sy wine
  3. Disable DirectX11 
    1. run winecfg
    2. switch to tab ‘Libraries’
    3. select ‘d3d11’ in the drop-down menu or type it in and click ‘Add’
    4. click ‘edit…’ and set it to disabled
    5. click ‘OK’
  4. Install msttcore fonts
    1. winetricks corefonts
  5. Set Windows version to Windows XP
    1. winetricks winxp
  6. (Dvorak keymap users only) Set keymap to US to allow for hotkeys to work
    1. setxkbmap us

It’s not perfect. Battle.net splash screens don’t load (no news, patch info) and the first few moments in the game stutter (but it’s fine after that.) Without DX11 the game doesn’t quite look as shiny but is still quite playable. I hope future versions of WINE will help with this problem, but this is what I’m using for now.