Difference between revisions of "Talk:QEMU"

From ArchWiki
Jump to: navigation, search
(Removing sections for EOL versions of Windows: new section)
m (Creating bridge manually: expand my previous reply)
(22 intermediate revisions by 7 users not shown)
Line 4: Line 4:
 
--[[User:Synchronicity|Synchronicity]] ([[User talk:Synchronicity|talk]]) 19:23, 9 May 2012 (UTC)
 
--[[User:Synchronicity|Synchronicity]] ([[User talk:Synchronicity|talk]]) 19:23, 9 May 2012 (UTC)
  
== thoughts / suggestions on networking nitty gritty section ==
+
== <s>qemu-* vs qemu-system-*?</s> ==
  
I followed the Beginner's Guide to installing Arch and setting up {{ic|/etc/rc.conf}}. I have also installed {{pkg|dnsmasq}}. When following the QEMU/KVM how-to I was unable to get my bridge interface to see the DHCP server of my modem until I amended my {{ic|/etc/rc.conf}} to include and bring up the loopback interface i.e.
+
What's the difference between qemu-* and qemu-system-*? So far, I haven't seen too much of a difference, except for a quite noticeable difference in filesize:
{{bc|<nowiki>
+
lo="lo up"
+
eth0="eth0 up"
+
br0="dhcp"
+
INTERFACES=(lo eth0 br0)
+
gateway="default gw 192.168.0.1"
+
ROUTES=(gateway)
+
</nowiki>}}
+
 
+
As this is not part of the beginners {{ic|/etc/rc.conf}} it might help others that have got stuck with this part to read this and maybe considered, if correct, a useful addition to the how-to.  It would be good to get confirmation from those-that-know if this is the best foot forward, so to speak.
+
 
+
Ed 17/05/10
+
 
+
The networking configuration here relies on ifconfig, which is deprecated. It should be changes to use netcfg:
+
 
+
https://wiki.archlinux.org/index.php/Netcfg#Configuring_a_bridge_for_use_with_virtual_machines_.28VMs.29
+
 
+
(The default configuration of netcfg works)
+
 
+
[[User:Zealjagannatha|Zealjagannatha]] ([[User talk:Zealjagannatha|talk]]) 01:20, 12 July 2012 (UTC)
+
 
+
== VDE networking ==
+
 
+
The instructions provided for VDE networking did not work. Instead I did the following which ''did'' work:
+
  
 
{{bc|
 
{{bc|
vde_switch -daemon
+
# ls -l $(which qemu{-system,}-x86_64);
 
+
-rwxr-xr-x 1 root root 4793008 Jun  8 02:14 /usr/bin/qemu-system-x86_64
slirpvde --dhcp --daemon
+
-rwxr-xr-x 1 root root 2406208 Jun  8 02:14 /usr/bin/qemu-x86_64
 
}}
 
}}
  
Then to start the VM with a connection to the network of the host:
+
: Next time please add a signature after your post by typing four tildes ({{ic|<nowiki>~~~~</nowiki>}}). Thanks.
 +
: There have been some changes recently and the wiki page isn't yet fully updated. I guess that the old {{ic|qemu}} binary has been replaced by {{ic|qemu-system-*}} depending on architecture and {{ic|qemu-*}} binary is used internally. See qemu(1) for more details.
 +
: -- [[User:Lahwaacz|Lahwaacz]] ([[User talk:Lahwaacz|talk]]) 09:47, 16 July 2013 (UTC)
  
{{bc|1=
+
::I've done some more research on this: {{ic|qemu-system-*}} binaries emulate full virtual machine (that's currently described in [[QEMU]], some time ago {{ic|qemu}} was used for this purpose), whereas {{ic|qemu-*}} binaries allow executing statically linked binaries for different architecture than the host system. You can even [http://www.gentoo.org/proj/en/base/embedded/handbook/?part=1&chap=5 chroot] into different-architecture system emulating even dynamically linked binaries. Perhaps some mention of this could be added to [[QEMU]]. -- [[User:Lahwaacz|Lahwaacz]] ([[User talk:Lahwaacz|talk]]) 20:54, 22 July 2013 (UTC)
kvm -net nic,macaddr=52:54:00:00:EE:03 -net vde whatever.qcow
+
 
}}
+
:::No reply, closing. -- [[User:Lahwaacz|Lahwaacz]] ([[User talk:Lahwaacz|talk]]) 18:11, 5 September 2013 (UTC)
  
The above method is also less invasive. Any support/objections to replacing the VDE networking instructions in the article with these? If the current instructions bring attention to features that the above method does not, how can they integrated?
+
== Creating bridge manually ==
--[[User:AndreasBWagner|AndreasBWagner]] 22:02, 17 April 2011 (EDT)
+
  
:I'm not very acquainted with QEMU nor VDE, anyway I would suggest to add your code as an "Alternative method", so that people will be able to choose what they like best, and if the current code doesn't work any longer for anybody (maybe due to version upgrades?) it will be removed altogether. -- [[User:Kynikos|Kynikos]] 10:01, 18 April 2011 (EDT)
+
I really don't know what to do with this section. I'd say it has been superseded by [[QEMU#Creating bridge using qemu-bridge-helper]] (available since qemu-1.1, we now have qemu-1.5) - or is someone still using this method? Perhaps link to https://en.wikibooks.org/wiki/QEMU/Networking#TAP_interfaces or http://wiki.qemu.org/Documentation/Networking/NAT is sufficient. What do you think? -- [[User:Lahwaacz|Lahwaacz]] ([[User talk:Lahwaacz|talk]]) 20:42, 22 July 2013 (UTC)
  
== needed Tap networking with QEMU scripts a rewrite? ==
+
:Actually, I've become a happy user of this method. I've written some scripts to easily create bridge interface, TAP interface, and combined with Xyne's [http://xyne.archlinux.ca/notes/network/dhcp_with_dns.html excellent scripts] to set up NAT and launch DHCP server, I have complete solution to easily manage multiple VMs on one (or even more) bridge.
 +
:My scripts are available on github: [https://github.com/lahwaacz/archlinux-dotfiles/blob/master/Scripts/qemu-launcher.sh], [https://github.com/lahwaacz/archlinux-dotfiles/blob/master/Scripts/qemu-tap-helper.sh], [https://github.com/lahwaacz/archlinux-dotfiles/blob/master/Scripts/qemu-mac-hasher.py] but I won't probably integrate them into the wiki, I'l just leave a note when I do some more testing.
 +
:The thing is, what to do with the current content? Personally I think that links to [https://en.wikibooks.org/wiki/QEMU/Networking#TAP_interfaces], [http://wiki.qemu.org/Documentation/Networking/NAT] and my scripts are sufficient (of course others are welcome). I'd also leave the note at the end to ''disable the firewall on the bridge'', I find it extremely useful.
 +
:-- [[User:Lahwaacz|Lahwaacz]] ([[User talk:Lahwaacz|talk]]) 18:24, 5 September 2013 (UTC)
  
Scripts from Tap networking with QEMU section uses tunctl provided by the package uml_utilities but doesn't exist on the repositories.
+
==  Preparing an (Arch) Linux guest  ==
  
== Removing sections for EOL versions of Windows ==
+
adding the virtio modules to use virtual devices doesn't appear to be necessary as of the VM I built this week(Jul 26, 2013). Kernel 3.9.9-1
 +
[[User:Surlyjake|Surlyjake]] ([[User talk:Surlyjake|talk]]) 03:42, 27 July 2013 (UTC)
  
I think we should remove the instructions/sections for versions of Windows that are not supported by Microsoft anymore/are considered end-of-life. [[QEMU#Windows-specific_notes]] still has sections for Windows 95 through Windows 2000. Microsoft stopped supporting Windows 2000 in 2010. I think we should keep anything that is generally applicable to Windows XP (and recent) from those sections and get rid of the rest of it.
+
:In newer kernel versions (I think since 3.4) the kernel modules are loaded automatically. I'd still keep the section as it is for now, linux-lts is still at 3.0. -- [[User:Lahwaacz|Lahwaacz]] ([[User talk:Lahwaacz|talk]]) 21:09, 20 August 2013 (UTC)
  
Does anyone object?<br>
+
==  Starting QEMU virtual machines with Systemd  ==
-- [[User:Jstjohn|Jstjohn]] ([[User talk:Jstjohn|talk]]) 08:29, 13 June 2013 (UTC)
+
The custom systemd service script does not work. It always fails with {{ic|Failed at step EXEC spawning /usr/bin/qemu-{type}: No such file or directory}}. To Fix this modify the ExecStart command {{bc|1=ExecStart=/usr/bin/sh -c "/usr/bin/qemu-${type} -name %i -nographic ${args}"}}
 +
Also {{ic|echo 'system_powerdown' &#124; nc localhost 7101}} kills the VM immediatly. To fix this change the stop script. It simply checks each second if the main process is still running. {{bc|1=ExecStop=/usr/bin/sh -c "${haltcmd} && while [[ `pidof qemu-${type} | grep $MAINPID` ]]; do sleep 1; done"}}
 +
{{ic|gnu-netcat}} does not work to connect to the monitor. You need to use {{ic|openbsd-netcat}}. -- [[User:Ant32|Ant32]] ([[User talk:Ant32|talk]]) 17:48, 5 September 2013 (UTC)

Revision as of 18:32, 5 September 2013

Linear RAID

When I was updating the article yesterday, I had tried to fit the section about linear raid (boot a VM from a partition by prepending a MBR to it) into the article better. But I'm not sure the technique described is the right one at all. It looks like it works, but wouldn't it be easier to install a bootloader directly to the partition (e.g. syslinux)? Then the VM could be booted directly from the partition simply by using it as its virtual disk. --Synchronicity (talk) 19:23, 9 May 2012 (UTC)

qemu-* vs qemu-system-*?

What's the difference between qemu-* and qemu-system-*? So far, I haven't seen too much of a difference, except for a quite noticeable difference in filesize:

# ls -l $(which qemu{-system,}-x86_64);
-rwxr-xr-x 1 root root 4793008 Jun  8 02:14 /usr/bin/qemu-system-x86_64
-rwxr-xr-x 1 root root 2406208 Jun  8 02:14 /usr/bin/qemu-x86_64
Next time please add a signature after your post by typing four tildes (~~~~). Thanks.
There have been some changes recently and the wiki page isn't yet fully updated. I guess that the old qemu binary has been replaced by qemu-system-* depending on architecture and qemu-* binary is used internally. See qemu(1) for more details.
-- Lahwaacz (talk) 09:47, 16 July 2013 (UTC)
I've done some more research on this: qemu-system-* binaries emulate full virtual machine (that's currently described in QEMU, some time ago qemu was used for this purpose), whereas qemu-* binaries allow executing statically linked binaries for different architecture than the host system. You can even chroot into different-architecture system emulating even dynamically linked binaries. Perhaps some mention of this could be added to QEMU. -- Lahwaacz (talk) 20:54, 22 July 2013 (UTC)
No reply, closing. -- Lahwaacz (talk) 18:11, 5 September 2013 (UTC)

Creating bridge manually

I really don't know what to do with this section. I'd say it has been superseded by QEMU#Creating bridge using qemu-bridge-helper (available since qemu-1.1, we now have qemu-1.5) - or is someone still using this method? Perhaps link to https://en.wikibooks.org/wiki/QEMU/Networking#TAP_interfaces or http://wiki.qemu.org/Documentation/Networking/NAT is sufficient. What do you think? -- Lahwaacz (talk) 20:42, 22 July 2013 (UTC)

Actually, I've become a happy user of this method. I've written some scripts to easily create bridge interface, TAP interface, and combined with Xyne's excellent scripts to set up NAT and launch DHCP server, I have complete solution to easily manage multiple VMs on one (or even more) bridge.
My scripts are available on github: [1], [2], [3] but I won't probably integrate them into the wiki, I'l just leave a note when I do some more testing.
The thing is, what to do with the current content? Personally I think that links to [4], [5] and my scripts are sufficient (of course others are welcome). I'd also leave the note at the end to disable the firewall on the bridge, I find it extremely useful.
-- Lahwaacz (talk) 18:24, 5 September 2013 (UTC)

Preparing an (Arch) Linux guest

adding the virtio modules to use virtual devices doesn't appear to be necessary as of the VM I built this week(Jul 26, 2013). Kernel 3.9.9-1 Surlyjake (talk) 03:42, 27 July 2013 (UTC)

In newer kernel versions (I think since 3.4) the kernel modules are loaded automatically. I'd still keep the section as it is for now, linux-lts is still at 3.0. -- Lahwaacz (talk) 21:09, 20 August 2013 (UTC)

Starting QEMU virtual machines with Systemd

The custom systemd service script does not work. It always fails with Failed at step EXEC spawning /usr/bin/qemu-{type}: No such file or directory. To Fix this modify the ExecStart command
ExecStart=/usr/bin/sh -c "/usr/bin/qemu-${type} -name %i -nographic ${args}"
Also echo 'system_powerdown' | nc localhost 7101 kills the VM immediatly. To fix this change the stop script. It simply checks each second if the main process is still running.
ExecStop=/usr/bin/sh -c "${haltcmd} && while [[ `pidof qemu-${type} | grep $MAINPID` ]]; do sleep 1; done"

gnu-netcat does not work to connect to the monitor. You need to use openbsd-netcat. -- Ant32 (talk) 17:48, 5 September 2013 (UTC)