{"id":4288,"date":"2015-04-06T10:16:17","date_gmt":"2015-04-06T17:16:17","guid":{"rendered":"http:\/\/www.graphics-muse.org\/wp\/?p=4288"},"modified":"2015-04-06T10:16:17","modified_gmt":"2015-04-06T17:16:17","slug":"networking-with-qemu-and-kvm-speedup","status":"publish","type":"post","link":"https:\/\/www.graphics-muse.org\/wp\/?p=4288","title":{"rendered":"Networking with QEMU and KVM speedup"},"content":{"rendered":"

Networking in QEMU<\/h3>\n

I’ve recently had a need to test UEFI booting for a disk image.\u00a0 I stumbled upon OVMF<\/a>, a bios that will handle UEFI booting.\u00a0 It works pretty well but doesn’t remember its config sometimes.\u00a0 But that’s not why I’m writing this.<\/p>\n

In my disk image I need dual network interfaces that are on specific networks.\u00a0 I don’t need tap<\/em> interfaces.\u00a0 I can live with the slower user-mode<\/em> interfaces.\u00a0 But I needed to put them on separate networks.\u00a0 So I did this.<\/p>\n

\n
-netdev user,id=user0,dhcpstart=192.168.20.20,hostfwd=tcp::5555-:22 -device e1000,netdev=user0<\/pre>\n
-netdev user,id=user1,dhcpstart=192.168.50.50,hostfwd=tcp::5556-:22 -device e1000,netdev=user1<\/pre>\n<\/blockquote>\n
I googled till I was blue to figure out how to do this.\u00a0 You can set the dhcpstart<\/strong> address but qemu_system_x86-64<\/em> spews the following message:<\/p>\n
device 'user' could not be initialized<\/pre>\n
It doesn’t say why, but after fiddling with it for a long time it became obvious that this was a configuration error.\u00a0 There just doesn’t seem to be any explanation as to what configuration is wrong.<\/p>\n
Finally I found a site with an example<\/a>.\u00a0 The key appears to be that you have to include the host’s network address<\/strong> on the network that interface will be in.\u00a0 Without this specification there is no mapping of the guest interface to a host interface.\u00a0 Here is what the correct configuration should look like.<\/p>\n
\n
-netdev user,id=user0,net=192.168.20.0\/24,dhcpstart=192.168.20.20,hostfwd=tcp::5555-:22 -device e1000,netdev=user0<\/pre>\n
-netdev user,id=user1,net=192.168.50.0\/24,dhcpstart=192.168.50.50,hostfwd=tcp::5556-:22 -device e1000,netdev=user1<\/pre>\n<\/blockquote>\n
Now both interfaces will come up on the assigned networks.\u00a0 The hostfwd<\/em> option is used to map host ports to guest ports, with the larger number (the first one) mapping to the guest’s port.\u00a0 Here I’m mapping ports to the ssh port on the guest.\u00a0 Since I’m using user-mode networking this is required otherwise the default firewall in the guest prevents me from accessing it from the host.<\/p>\n
KVM Speedup<\/h3>\n
Another thing I discovered when running qemu_system_x86_64 is that it was slow on my Fedora 21 box.\u00a0 The reason is simple:\u00a0 you can’t run this command manually with KVM speedups (which are significant) if you’re already running libvirtd<\/em>.\u00a0 You can go through the hoops of tying the two together, but for a quick solution to run a qemu session with full virtualization to get much better performance without dealing with libvirtd just shutoff libvirtd.<\/p>\n
sudo service libvirtd stop<\/pre>\n
That’s using archaic service<\/em> format instead of the ugly sysctl<\/em> interface (that you very little, systemd) but it works.\u00a0 Again, this is for Fedora.\u00a0 Your distro mileage will vary.<\/p>\n","protected":false},"excerpt":{"rendered":"
Networking in QEMU I’ve recently had a need to test UEFI booting for a disk image.\u00a0 I stumbled upon OVMF, a bios that will handle UEFI booting.\u00a0 It works pretty well but doesn’t remember its config sometimes.\u00a0 But that’s not why I’m writing this. In my disk image I need dual network interfaces that are […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"jetpack_post_was_ever_published":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[35,8,5,295],"tags":[595,634,598,528,298,239,139,597,596,641],"class_list":{"0":"post-4288","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-fedora","7":"category-hardware","8":"category-linux","9":"category-virtualization","10":"tag-bios","11":"tag-fedora","12":"tag-kernel-based-virtual-machine","13":"tag-kvm","14":"tag-libvirtd","15":"tag-qemu","16":"tag-ssh-port","17":"tag-tuntap","18":"tag-unified-extensible-firmware-interface","19":"tag-virtualization","20":"czr-hentry"},"jetpack_publicize_connections":[],"aioseo_notices":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pe9t8-17a","jetpack_sharing_enabled":true,"jetpack-related-posts":[],"jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/www.graphics-muse.org\/wp\/index.php?rest_route=\/wp\/v2\/posts\/4288","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.graphics-muse.org\/wp\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.graphics-muse.org\/wp\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.graphics-muse.org\/wp\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.graphics-muse.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4288"}],"version-history":[{"count":2,"href":"https:\/\/www.graphics-muse.org\/wp\/index.php?rest_route=\/wp\/v2\/posts\/4288\/revisions"}],"predecessor-version":[{"id":4290,"href":"https:\/\/www.graphics-muse.org\/wp\/index.php?rest_route=\/wp\/v2\/posts\/4288\/revisions\/4290"}],"wp:attachment":[{"href":"https:\/\/www.graphics-muse.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4288"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.graphics-muse.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4288"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.graphics-muse.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4288"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}