9:09 p.m.
Hi all.
I've been playing around with KVM for a bit now and have several virtual
machines up and running. Having passed what I considered "first look"
stage, I'm ready to start using libvirt as a manager. For reference,
pre-libvirt, I have started this VM with:
/kvm -net nic,model=virtio -net tap,ifname=tap5,script=no -drive
file=test1.img,if=virtio,boot=on -curses -no-reboot -m 1g -smp 2/
I have a test environment I like to play with, and created the initial
domain XML using virt-install:
/virt-install --name "Test" --ram 1024 --vcpus=2 --cpu host
--description "Test VM" --import --file test1.img --os-type=linux
--os-variant=virtio26 --network bridge=br0,model=virtio --graphics=none
--autostart --prompt/
When I look in /var/log/libvirt/qemu/Test.log I see the VM is started
with the command (edited down to the relevant parts):
//usr/bin/qemu-kvm -S -m 1024 -smp 2 -name Test,process=qemu:Test
-nographics -boot c -drive file=/kvms/test1.img,if=none,boot=on
/This has two problems:
1) The "-S" is keeping the system from booting
2) the "if=none" needs to be "if=virtio"
I've confirmed both by changing -nographics to -curses and watching what
happens. For #1, its a big fat nothing (no surprise since -S turns off
the CPUs), for #2 grub loads and the kernel boots, but my /dev/vda3
isn't found so "init" can't start.
I'm anticipating a 3rd problem: I don't see where to specify that I
want the VM to use "tap5" of my bridged network.
Can some kind soul please let me know what I need to change in the
domain XML file to fix these issues?
Thanks,
Kevin
ps. I've post this to my blog at
http://www.kevinsthoughts.com/2011/08/kvm-management-libvirt/ if anyone
would prefer to answer there.
9:14 a.m.
On 08/29/2011 08:09 PM, Kevins Thoughts wrote:
When I look in /var/log/libvirt/qemu/Test.log I see the VM is started
with the command (edited down to the relevant parts):
//usr/bin/qemu-kvm -S -m 1024 -smp 2 -name Test,process=qemu:Test
-nographics -boot c -drive file=/kvms/test1.img,if=none,boot=on
/This has two problems:
1) The "-S" is keeping the system from booting
This is intentional. Libvirt has to make some changes via the monitor,
since qemu does not expose all functionality from the command line, so
libvirt blindly starts qemu with -S, makes subsequent monitor changes,
and then released the vcpus via monitor command (unless you used the
VIR_DOMAIN_START_PAUSED flag to keep things paused). There is no XML to
control this, nor does there need to be, given the existence of
virDomainCreateWithFlags().
2) the "if=none" needs to be "if=virtio"
Have you tried 'virsh domxml-from-native qemu-argv /path/to/args' for a
shell-style command line containing the qemu command you want to run?
It's not perfect, but may give you some hints on this regard.
Meanwhile, according to the documentation, <target dev=...
bus='virtio'/> inside your <drive> xml appears to be the right way to
request a virtio drive. Paste the actual XML you are trying to use, so
we can offer suggestions relative to your questions.
I've confirmed both by changing -nographics to -curses and watching what
happens. For #1, its a big fat nothing (no surprise since -S turns off
the CPUs), for #2 grub loads and the kernel boots, but my /dev/vda3
isn't found so "init" can't start.
I'm anticipating a 3rd problem: I don't see where to specify that I
want the VM to use "tap5" of my bridged network.
Does the documentation help?
http://libvirt.org/formatdomain.html#elementsNICS
--
Eric Blake eblake(a)redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
10:59 a.m.
On 8/30/2011 9:14 AM, Eric Blake wrote:
On 08/29/2011 08:09 PM, Kevins Thoughts wrote:
> <clip>
>
> 1) The "-S" is keeping the system from booting
This is intentional. Libvirt has to make some changes via the monitor,
since qemu does not expose all functionality from the command line, so
libvirt blindly starts qemu with -S, makes subsequent monitor changes,
and then released the vcpus via monitor command (unless you used the
VIR_DOMAIN_START_PAUSED flag to keep things paused). There is no XML to
control this, nor does there need to be, given the existence of
virDomainCreateWithFlags().
Alas, for whatever reason, the vcpus do not appear to be being
released. XML below...
> 2) the "if=none" needs to be "if=virtio"
Have you tried 'virsh domxml-from-native qemu-argv /path/to/args' for a
shell-style command line containing the qemu command you want to run?
It's not perfect, but may give you some hints on this regard.
No I haven't, thanks for that suggestion.
Meanwhile, according to the documentation,<target dev=...
bus='virtio'/> inside your<drive> xml appears to be the right way to
request a virtio drive. Paste the actual XML you are trying to use, so
we can offer suggestions relative to your questions.
Actually, I did read the documentation and agree - at least that was my
best guess, but its not working. The generated command being invoked
has "-drive file=/kvms/test1.img,if=none,boot=on" specified.
Here is the XML file created by the command: virt-install --name "Test"
--ram 1024 --vcpus=2 --cpu host --description "Test VM" --import --file
test1.img --os-type=linux --os-variant=virtio26 --network
bridge=br0,model=virtio --graphics=none --autostart --prompt
<Test.xml>
<domain type='kvm'>
<name>Test</name>
<uuid>b0784171-0662-80ce-caad-c9e3c7fe0952</uuid>
<description>Test VM</description>
<memory>1048576</memory>
<currentMemory>1048576</currentMemory>
<vcpu>2</vcpu>
<os>
<type arch='x86_64' machine='pc-0.13'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
<pae/>
</features>
<cpu match='exact'>
<model>Opteron_G3</model>
<vendor>AMD</vendor>
<feature policy='require' name='skinit'/>
<feature policy='require' name='vme'/>
<feature policy='require' name='mmxext'/>
<feature policy='require' name='fxsr_opt'/>
<feature policy='require' name='cr8legacy'/>
<feature policy='require' name='ht'/>
<feature policy='require' name='3dnowprefetch'/>
<feature policy='require' name='3dnowext'/>
<feature policy='require' name='wdt'/>
<feature policy='require' name='extapic'/>
<feature policy='require' name='pdpe1gb'/>
<feature policy='require' name='osvw'/>
<feature policy='require' name='cmp_legacy'/>
<feature policy='require' name='3dnow'/>
</cpu>
<clock offset='utc'/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>restart</on_crash>
<devices>
<emulator>/usr/bin/qemu-kvm</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='raw'/>
<source file='/kvms/test1.img'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00'
slot='0x04' function='0x0'/>
</disk>
<interface type='bridge'>
<mac address='52:54:00:f3:28:7b'/>
<source bridge='br0'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x00'
slot='0x03' function='0x0'/>
</interface>
<serial type='pty'>
<target port='0'/>
</serial>
<console type='pty'>
<target type='serial' port='0'/>
</console>
<memballoon model='virtio'>
<address type='pci' domain='0x0000' bus='0x00'
slot='0x05' function='0x0'/>
</memballoon>
</devices>
</domain>
Does the documentation help?
http://libvirt.org/formatdomain.html#elementsNICS
Looks like I could perhaps add a "<target dev='tap5'/>" to the
bridge
interface section. The documentation refers to using "tun" devices, and
I use "tap" devices, but perhaps that's close enough.
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