guestfish/libguestfs takes legacy qemu instead of kvm?

[Kirby Zhou]

guestfish takes legacy qemu instead of kvm?

 

]# rpm -q libguestfs --requires | fgrep qemu

qemu-system-x86 >= 0.10.5

 

]# rpm -q libguestfs guestfish

libguestfs-1.2.3-1.el5

guestfish-1.2.3-1.el5

 

[@djt_10_48 ~]# guestfish -i kvm-rhel5guest 

Could not open '/dev/kqemu' - QEMU acceleration layer not activated: No such
file or directory

 

 

How can I let guestfish/libguestfs takes kvm?

 

  Regards

  Kirby Zhou

[Richard W.M. Jones]

On Sun, Aug 08, 2010 at 12:05:58PM +0800, Kirby Zhou wrote:
>  guestfish takes legacy qemu instead of kvm?
>  ]# rpm -q libguestfs --requires | fgrep qemu
>  qemu-system-x86 >= 0.10.5 
To make it clear, this is EPEL-5.  There was some still unresolved
problem with adding a dependency on KVM:

  https://fedorahosted.org/rel-eng/ticket/2982

As a result, we have to depend on qemu (software emulation) instead.
However you can easily change this at runtime by setting the
LIBGUESTFS_QEMU environment variable:

  http://libguestfs.org/guestfs.3.html#libguestfs_qemu
  http://libguestfs.org/guestfs.3.html#qemu_wrappers

In RHEL 6 it's all going to be different again.  The same
qemu-system-x86 RPM is actually KVM.  We combine qemu and KVM sources
during the build to make a 'qemu-kvm' binary which can do both
software emulation (TCG) and hardware virt (KVM).

>  [@djt_10_48 ~]# guestfish -i kvm-rhel5guest 
>  Could not open '/dev/kqemu' - QEMU acceleration layer not activated: No such
>  file or directory 
This is just a warning -- ignore it.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine.  Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/

[Libguestfs] guestfish/libguestfs takes legacy qemu instead of kvm?

[Kirby Zhou]

Thanks very much.
BTW, I have a small question, why libguestfs depends on QEMU instead of
libvirt?
If we take libvirt, we can easily run libguestfs with xen, virtualbox,
vmware, etc.

Regards,
   Kirby Zhou    
   from   SOHU-RD   [phone]


-----Original Message-----
From: libguestfs-bounces(a)redhat.com [mailto:[e-mail]]
On Behalf Of Richard W.M. Jones
Sent: Sunday, August 08, 2010 7:26 PM
To: EPEL development disccusion
Cc: libguestfs(a)redhat.com
Subject: Re: [Libguestfs] guestfish/libguestfs takes legacy qemu instead of
kvm?

On Sun, Aug 08, 2010 at 12:05:58PM +0800, Kirby Zhou wrote:
>  guestfish takes legacy qemu instead of kvm?
>  ]# rpm -q libguestfs --requires | fgrep qemu
>  qemu-system-x86 >= 0.10.5 
To make it clear, this is EPEL-5.  There was some still unresolved
problem with adding a dependency on KVM:

  https://fedorahosted.org/rel-eng/ticket/2982

As a result, we have to depend on qemu (software emulation) instead.
However you can easily change this at runtime by setting the
LIBGUESTFS_QEMU environment variable:

  http://libguestfs.org/guestfs.3.html#libguestfs_qemu
  http://libguestfs.org/guestfs.3.html#qemu_wrappers

In RHEL 6 it's all going to be different again.  The same
qemu-system-x86 RPM is actually KVM.  We combine qemu and KVM sources
during the build to make a 'qemu-kvm' binary which can do both
software emulation (TCG) and hardware virt (KVM).

>  [@djt_10_48 ~]# guestfish -i kvm-rhel5guest 
>  Could not open '/dev/kqemu' - QEMU acceleration layer not activated: No
such
>  file or directory 
This is just a warning -- ignore it.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat
http://people.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine.  Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/

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[Libguestfs] guestfish/libguestfs takes legacy qemu instead of kvm?

[Matthew Booth]

On 10/08/10 10:27, Kirby Zhou wrote:
>  Thanks very much.
>  BTW, I have a small question, why libguestfs depends on QEMU instead of
>  libvirt?
>  If we take libvirt, we can easily run libguestfs with xen, virtualbox,
>  vmware, etc. 
Not quite. There's more to making an appliance run on a target 
hypervisor than just creating an appropriate domain. The appliance 
itself must support the target.

However, there's an argument to be made about using libvirt to isolate 
ourselves from the whims of qemu command-line argument changes.

Matt
-- 
Matthew Booth, RHCA, RHCSS
Red Hat Engineering, Virtualisation Team

GPG ID:  D33C3490
GPG FPR: 3733 612D 2D05 5458 8A8A 1600 3441 EA19 D33C 3490

[Libguestfs] guestfish/libguestfs takes legacy qemu instead of kvm?

[Richard W.M. Jones]

On Tue, Aug 10, 2010 at 05:27:56PM +0800, Kirby Zhou wrote:
>  Thanks very much.  BTW, I have a small question, why libguestfs
>  depends on QEMU instead of libvirt?  If we take libvirt, we can
>  easily run libguestfs with xen, virtualbox, vmware, etc. 
It's considerably more complex than that.

However you can already use libguestfs to analyze images from xen,
vmware, virtualbox and so on.  The fact that qemu is involved behind
the scenes doesn't matter -- indeed it's an advantage because qemu's
block layer supports many different container formats.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines.  Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v

[Libguestfs] guestfish/libguestfs takes legacy qemu instead of kvm?

[Kirby Zhou]

But pure QEMU is very very slow.

  Regards
  Kirby Zhou

-----Original Message-----
From: Richard W.M. Jones [mailto:[e-mail]] 
Sent: Tuesday, August 10, 2010 8:34 PM
To: Kirby Zhou
Cc: 'EPEL development disccusion'; libguestfs(a)redhat.com
Subject: Re: [Libguestfs] guestfish/libguestfs takes legacy qemu instead of
kvm?

On Tue, Aug 10, 2010 at 05:27:56PM +0800, Kirby Zhou wrote:
>  Thanks very much.  BTW, I have a small question, why libguestfs
>  depends on QEMU instead of libvirt?  If we take libvirt, we can
>  easily run libguestfs with xen, virtualbox, vmware, etc. 
It's considerably more complex than that.

However you can already use libguestfs to analyze images from xen,
vmware, virtualbox and so on.  The fact that qemu is involved behind
the scenes doesn't matter -- indeed it's an advantage because qemu's
block layer supports many different container formats.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat
http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines.  Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v

[Libguestfs] guestfish/libguestfs takes legacy qemu instead of kvm?

[Richard W.M. Jones]

On Wed, Aug 11, 2010 at 12:10:13AM +0800, Kirby Zhou wrote:
>  From: Richard W.M. Jones [mailto:[e-mail]] 
>  > On Tue, Aug 10, 2010 at 05:27:56PM +0800, Kirby Zhou wrote:
>  > > Thanks very much.  BTW, I have a small question, why libguestfs
>  > > depends on QEMU instead of libvirt?  If we take libvirt, we can
>  > > easily run libguestfs with xen, virtualbox, vmware, etc.
>  > 
>  > It's considerably more complex than that.
>
>  But pure QEMU is very very slow. 
OK, so I think what you're asking for is to be able to run libguestfs
with KVM (ie. hardware acceleration) either alongside another
hypervisor (eg. Xen) or inside another virtual machine.

This [hardware acceleration] is indeed not possible, and so you will
fall back to using software emulation (ie. pure TCG-based qemu), and
this is somewhat slow, although at least it works!

The only solution to this is some sort of nested virt.  Since I am at
the KVM Forum at the moment, I have been emphasizing the importance to
us of having nested virt at least in KVM.  But the implementation of
nested virt is very complex.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
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