6:13 p.m.
Hi,
I want to manage a 32 bit i686 guest on an x86_64 host with kvm and libvirt.
KVM is perfectly capable of doing this (look e.g. at
http://kvm.qumranet.com/kvmwiki/Guest_Support_Status) but libvirt did not
allow it.
So I created the attached patch to allow it and make it easy to extend the
capabilities of kvm and kqemu later on.
I did not add anything I'm not sure about, so I did not at 64bit guest on
32bit host (though the page linked above seems to indicate that it works) and
did not change the capabilities of kqemu at all (because I don't have any
experience with it and never used it).
Please consider merging.
Kind regards,
Gerd
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3:39 a.m.
On Tue, Jun 03, 2008 at 01:13:29AM +0200, Gerd von Egidy wrote:
Hi,
I want to manage a 32 bit i686 guest on an x86_64 host with kvm and libvirt.
KVM is perfectly capable of doing this (look e.g. at
http://kvm.qumranet.com/kvmwiki/Guest_Support_Status) but libvirt did not
allow it.
So I created the attached patch to allow it and make it easy to extend the
capabilities of kvm and kqemu later on.
This is incorrect. KVM is *not* exposing a i686 architecture CPU. It is
exposing an x86_64 virtualized CPU which is capable of running x86_64 or
i686 guests. No change is required.
Dan.
--
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4:49 a.m.
Hi Daniel,
> I want to manage a 32 bit i686 guest on an x86_64 host with kvm
and
> libvirt. KVM is perfectly capable of doing this (look e.g. at
> http://kvm.qumranet.com/kvmwiki/Guest_Support_Status) but libvirt did not
> allow it.
>
> So I created the attached patch to allow it and make it easy to extend
> the capabilities of kvm and kqemu later on.
This is incorrect. KVM is *not* exposing a i686 architecture CPU. It is
exposing an x86_64 virtualized CPU which is capable of running x86_64 or
i686 guests. No change is required.
Thanks for looking at my patch. I understand that KVM does not offer a i686
host cpu but allows x86_64 and i686 guests.
The reason for my patch was that I could not create i686 guests on a x86_64
host with KVM, the only option offered was using qemu.
I'm new to libvirt so I'm not that familiar with the capabilities-xml - so
take my findings with some salt ;)
Without my patch the capabilities look like this:
<capabilities>
<host>
<cpu>
<arch>x86_64</arch>
</cpu>
</host>
<guest>
<os_type>hvm</os_type>
<arch name='i686'>
<wordsize>32</wordsize>
<emulator>/usr/bin/qemu</emulator>
<machine>pc</machine>
<machine>isapc</machine>
<domain type='qemu'>
</domain>
</arch>
<features>
<pae/>
<nonpae/>
<acpi default='on' toggle='yes'/>
<apic default='on' toggle='no'/>
</features>
</guest>
<guest>
<os_type>hvm</os_type>
<arch name='x86_64'>
<wordsize>64</wordsize>
<emulator>/usr/bin/qemu-system-x86_64</emulator>
<machine>pc</machine>
<machine>isapc</machine>
<domain type='qemu'>
</domain>
<domain type='kvm'>
<emulator>/usr/bin/qemu-kvm</emulator>
</domain>
</arch>
<features>
<acpi default='on' toggle='yes'/>
<apic default='on' toggle='no'/>
</features>
</guest>
... (mips, sparc, etc. omitted)
The i686-guest section does not have a kvm-domain. So libvirt does not allow
the use of kvm for i686 guests.
With my patch the capabilities are:
<capabilities>
<host>
<cpu>
<arch>x86_64</arch>
</cpu>
</host>
<guest>
<os_type>hvm</os_type>
<arch name='i686'>
<wordsize>32</wordsize>
<emulator>/usr/bin/qemu</emulator>
<machine>pc</machine>
<machine>isapc</machine>
<domain type='qemu'>
</domain>
<domain type='kvm'>
<emulator>/usr/bin/qemu-kvm</emulator>
</domain>
</arch>
<features>
<pae/>
<nonpae/>
<acpi default='on' toggle='yes'/>
<apic default='on' toggle='no'/>
</features>
</guest>
<guest>
<os_type>hvm</os_type>
<arch name='x86_64'>
<wordsize>64</wordsize>
<emulator>/usr/bin/qemu-system-x86_64</emulator>
<machine>pc</machine>
<machine>isapc</machine>
<domain type='qemu'>
</domain>
<domain type='kvm'>
<emulator>/usr/bin/qemu-kvm</emulator>
</domain>
</arch>
<features>
<acpi default='on' toggle='yes'/>
<apic default='on' toggle='no'/>
</features>
</guest>
... (mips, sparc, etc. omitted)
As you can see the i686 guest section gained a kvm-domain with my patch which
allows me to install i686 KVM-guests on x86_64 hosts.
Kind regards,
Gerd
4:53 a.m.
On Tue, Jun 03, 2008 at 11:49:59AM +0200, Gerd v. Egidy wrote:
Hi Daniel,
> > I want to manage a 32 bit i686 guest on an x86_64 host with kvm and
> > libvirt. KVM is perfectly capable of doing this (look e.g. at
> > http://kvm.qumranet.com/kvmwiki/Guest_Support_Status) but libvirt did not
> > allow it.
> >
> > So I created the attached patch to allow it and make it easy to extend
> > the capabilities of kvm and kqemu later on.
>
> This is incorrect. KVM is *not* exposing a i686 architecture CPU. It is
> exposing an x86_64 virtualized CPU which is capable of running x86_64 or
> i686 guests. No change is required.
Thanks for looking at my patch. I understand that KVM does not offer a i686
host cpu but allows x86_64 and i686 guests.
The reason for my patch was that I could not create i686 guests on a x86_64
host with KVM, the only option offered was using qemu.
Yes you can - just select the x86_64 option. It is refering to the *CPU*
architecture that is virtualized, *not* the OS architecture. You can select
x86_64 CPU and then install a i386 operating system just fine.
Dan.
--
|: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :|
|: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :|
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5:06 a.m.
Hi Dan,
> Thanks for looking at my patch. I understand that KVM does not
offer a
> i686 host cpu but allows x86_64 and i686 guests.
>
> The reason for my patch was that I could not create i686 guests on a
> x86_64 host with KVM, the only option offered was using qemu.
Yes you can - just select the x86_64 option. It is refering to the *CPU*
architecture that is virtualized, *not* the OS architecture. You can select
x86_64 CPU and then install a i386 operating system just fine.
I'm using virt-manager to create a new vm. Virt-manager asks me "CPU
architecture" and "Hypervisor". When I select i686 as CPU arch I can not
select KVM as hypervisor, only qemu is offered.
If I understand you correctly, I should select x86_64 and KVM, even if I want
to run a 32 bit OS, right?
Isn't that counter-intuitive?
Kind regards,
Gerd
5:12 a.m.
On Tue, Jun 03, 2008 at 12:06:58PM +0200, Gerd v. Egidy wrote:
Hi Dan,
> > Thanks for looking at my patch. I understand that KVM does not offer a
> > i686 host cpu but allows x86_64 and i686 guests.
> >
> > The reason for my patch was that I could not create i686 guests on a
> > x86_64 host with KVM, the only option offered was using qemu.
>
> Yes you can - just select the x86_64 option. It is refering to the *CPU*
> architecture that is virtualized, *not* the OS architecture. You can select
> x86_64 CPU and then install a i386 operating system just fine.
I'm using virt-manager to create a new vm. Virt-manager asks me "CPU
architecture" and "Hypervisor". When I select i686 as CPU arch I can not
select KVM as hypervisor, only qemu is offered.
If I understand you correctly, I should select x86_64 and KVM, even if I want
to run a 32 bit OS, right?
Yes.
Dan.
--
|: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :|
|: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
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8:33 a.m.
Gerd v. Egidy wrote:
Hi Dan,
>> Thanks for looking at my patch. I understand that KVM does not offer a
>> i686 host cpu but allows x86_64 and i686 guests.
>>
>> The reason for my patch was that I could not create i686 guests on a
>> x86_64 host with KVM, the only option offered was using qemu.
> Yes you can - just select the x86_64 option. It is refering to the *CPU*
> architecture that is virtualized, *not* the OS architecture. You can select
> x86_64 CPU and then install a i386 operating system just fine.
I'm using virt-manager to create a new vm. Virt-manager asks me "CPU
architecture" and "Hypervisor". When I select i686 as CPU arch I can not
select KVM as hypervisor, only qemu is offered.
If I understand you correctly, I should select x86_64 and KVM, even if I want
to run a 32 bit OS, right?
Isn't that counter-intuitive?
This has confused quite a few people in the past (including myself). We
should probably add some better wording in virt-manager or some kind
of note explaining the terminology, but no matter what way you slice it
it's still easy to get tripped up on the concepts.
- Cole
6015
days inactive
6016
days old
6 comments
4 participants
participants (4)
-
Cole Robinson -
Daniel P. Berrange -
Gerd v. Egidy -
Gerd von Egidy