Running an x86 Yocto Linux image under QEMU KVM
Host OS preparation (VM manager host OS)
1. Enable KVM on the host machine, according to the guide below: https://wiki.yoctoproject.org/wiki/How_to_enable_KVM_for_Poky_qemu
2. Enable vhost-net to mitigate overheads on virtualization environment. Load vhost-net module on KVM Host. [root@dlp ~]#modprobe vhost_net [root@dlp ~]#lsmod | grep vhost
vhost_net 24241 0 macvtap 7867 1 vhost_net tun16825 3 vhost_net
Basically, follow the same guide as for enabling KVM on the host (step 1.), but replace kvm with vhost_net
3. Start the VM using the line below:
ubik@sentry:~/yoctoproject/build$ sudo kvm -kernel /home/ubik/yoctoproject/build/tmp/deploy/images/bzImage-qemux86.bin -net nic,model=virtio -net tap,vlan=0,ifname=tap0,script=no,downscript=no,vhost=on -drive file=/home/ubik/yoctoproject/build/tmp/deploy/images/core-image-core-qemux86.ext3,if=virtio -show-cursor -usb -usbdevice wacom-tablet -vga vmware -no-reboot -enable-kvm -cpu host -m 128 --append "vga=0 root=/dev/vda rw mem=128M ip=192.168.7.2::192.168.7.1:255.255.255.0 oprofile.timer=1 "
KVM version: ubik@sentry:~/yoctoproject/build$ kvm --version QEMU emulator version 1.0 (qemu-kvm-1.0), Copyright (c) 2003-2008 Fabrice Bellard
This is an example of running a virtualized Yocto image, with KVM active, cpu host features exported in the Yocto VM, paravirtualization enabled, and using virtio interfaces for disk access and networking.
On my machine, a Core i7 2600 (3.4GHz, 4 cores, 8 threads)/8 GB RAM/Intel SSD G3 120GB it start in around 7 seconds for a core-image-core. The same image boots in 20 seconds without virtualization optimization and it feels slower in usage.
See attached screenshots for VM running and proof of concept. Also attached is the patch for running our runqemu script with KVM and paravirt and virtio tech. In order to run it, use:
runqemu qemux86 core-image-core kvm
Log:
ubik@sentry:~/yoctoproject/build$ runqemu qemux86 core-image-core kvm Assuming core-image-core really means /home/ubik/yoctoproject/build/tmp/deploy/images/core-image-core-qemux86.ext3
Continuing with the following parameters: KERNEL: [/home/ubik/yoctoproject/build/tmp/deploy/images/bzImage-qemux86.bin] ROOTFS: [/home/ubik/yoctoproject/build/tmp/deploy/images/core-image-core-qemux86.ext3] FSTYPE: [ext3] Setting up tap interface under sudo [sudo] password for ubik: Acquiring lockfile for tap0... WARNING: distccd not present, no distcc support loaded. Running qemu... /home/ubik/yoctoproject/build/tmp/sysroots/x86_64-linux/usr/bin/qemu -kernel /home/ubik/yoctoproject/build/tmp/deploy/images/bzImage-qemux86.bin -net nic,model=virtio -net tap,vlan=0,ifname=tap0,script=no,downscript=no,vhost=on -drive file=/home/ubik/yoctoproject/build/tmp/deploy/images/core-image-core-qemux86.ext3,if=virtio -show-cursor -usb -usbdevice wacom-tablet -vga vmware -no-reboot -enable-kvm -cpu host -m 128 --append "vga=0 root=/dev/vda rw mem=128M ip=192.168.7.2::192.168.7.1:255.255.255.0 oprofile.timer=1 " vmsvga_value_write: guest runs Linux. Set 'tap0' nonpersistent Releasing lockfile of preconfigured tap device 'tap0' ubik@sentry:~/yoctoproject/build$
Guest OS preparation
The following kernel configs needs to be enabled:
CONFIG_PARAVIRT_GUEST=y
- CONFIG_PARAVIRT_TIME_ACCOUNTING is not set
- CONFIG_XEN_PRIVILEGED_GUEST is not set
CONFIG_KVM_CLOCK=y CONFIG_KVM_GUEST=y
- CONFIG_LGUEST_GUEST is not set
CONFIG_PARAVIRT=y
- CONFIG_PARAVIRT_SPINLOCKS is not set
CONFIG_PARAVIRT_CLOCK=y
- CONFIG_PARAVIRT_DEBUG is not set
CONFIG_VIRTIO_MMIO=y
