kvm or qemu-kvm?

kvm or qemu-kvm?

[Ross Boylan]

http://www.linux-kvm.org/page/HOWTO1 says to build kvm I should get the
latest kvm-release.tar.gz.

http://www.linux-kvm.org/page/Downloads says "If you want to use the
latest version of KVM kernel modules and supporting userspace, you can
download the latest version from
http://sourceforge.net/project/showfiles.php?group_id=180599."
That page shows the latest version is qemu-kvm-0.11.0.tar.gz.

The most recent kvm-release.tar.gz appears to be for kvm-88.

So which file should I start from?

Thanks.
Ross Boylan

Re: kvm or qemu-kvm?

[Charles Duffy]

Ross Boylan wrote:
> http://www.linux-kvm.org/page/HOWTO1 says to build kvm I should get the
> latest kvm-release.tar.gz.
> 
> http://www.linux-kvm.org/page/Downloads says "If you want to use the
> latest version of KVM kernel modules and supporting userspace, you can
> download the latest version from
> http://sourceforge.net/project/showfiles.php?group_id=180599."
> That page shows the latest version is qemu-kvm-0.11.0.tar.gz.
> 
> The most recent kvm-release.tar.gz appears to be for kvm-88.
> 
> So which file should I start from?

If you don't know what you want, you want qemu-kvm, which is based off a 
stable release of qemu.

Re: kvm or qemu-kvm?

[Ross Boylan]

On Wed, 2009-09-30 at 20:51 -0500, Charles Duffy wrote:
> Ross Boylan wrote:
> > http://www.linux-kvm.org/page/HOWTO1 says to build kvm I should get the
> > latest kvm-release.tar.gz.
> > 
> > http://www.linux-kvm.org/page/Downloads says "If you want to use the
> > latest version of KVM kernel modules and supporting userspace, you can
> > download the latest version from
> > http://sourceforge.net/project/showfiles.php?group_id=180599."
> > That page shows the latest version is qemu-kvm-0.11.0.tar.gz.
> > 
> > The most recent kvm-release.tar.gz appears to be for kvm-88.
> > 
> > So which file should I start from?
> 
> If you don't know what you want, you want qemu-kvm, which is based off a 
> stable release of qemu.
I'm trying to follow the advice on the bug reporting page to "Please use
the latest release version of kvm at the time you submit the bug."
Ross

Re: kvm or qemu-kvm?

[Avi Kivity]

On 09/30/2009 04:21 AM, Ross Boylan wrote:
> http://www.linux-kvm.org/page/HOWTO1 says to build kvm I should get the
> latest kvm-release.tar.gz.
>
> http://www.linux-kvm.org/page/Downloads says "If you want to use the
> latest version of KVM kernel modules and supporting userspace, you can
> download the latest version from
> http://sourceforge.net/project/showfiles.php?group_id=180599."
> That page shows the latest version is qemu-kvm-0.11.0.tar.gz.
>
> The most recent kvm-release.tar.gz appears to be for kvm-88.
>
> So which file should I start from?
>    

qemu-kvm is the userspace component, kvm-kmod is the kernel component as 
an external module.  'kvm' is a package containing both.

In general the best place to start is with the distro provided packages.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

Re: kvm or qemu-kvm?

[Ross Boylan]

On Thu, 2009-10-01 at 18:42 +0200, Avi Kivity wrote:
> On 09/30/2009 04:21 AM, Ross Boylan wrote:
> > http://www.linux-kvm.org/page/HOWTO1 says to build kvm I should get the
> > latest kvm-release.tar.gz.
> >
> > http://www.linux-kvm.org/page/Downloads says "If you want to use the
> > latest version of KVM kernel modules and supporting userspace, you can
> > download the latest version from
> > http://sourceforge.net/project/showfiles.php?group_id=180599."
> > That page shows the latest version is qemu-kvm-0.11.0.tar.gz.
> >
> > The most recent kvm-release.tar.gz appears to be for kvm-88.
> >
> > So which file should I start from?
> >    
> 
> qemu-kvm is the userspace component, kvm-kmod is the kernel component as 
> an external module.  'kvm' is a package containing both.
That helps a lot; maybe that info could go up on the bugs or faq page.
I couldn't find it (that is, there is info that there are kernel and
user space components, but not how these relate to the tar files).
> 
> In general the best place to start is with the distro provided packages.
> 
My distro (Debian) is only at 85, even in unstable.  Since it wasn't
current, and also the dependencies will have wide effects on my system
(which I'm trying to keep at the stable release Lenny), I figured
getting the current source and building it myself would be the best
move.  For other reasons I'm already running a 2.6.30 kernel from
Debian, which includes kernel side kvm.  So I figure I only need to mess
with user space.

Ross

Re: kvm or qemu-kvm?

[Avi Kivity]

On 10/01/2009 06:51 PM, Ross Boylan wrote:
>>> So which file should I start from?
>>>
>>>        
>> qemu-kvm is the userspace component, kvm-kmod is the kernel component as
>> an external module.  'kvm' is a package containing both.
>>      
> That helps a lot; maybe that info could go up on the bugs or faq page.
> I couldn't find it (that is, there is info that there are kernel and
> user space components, but not how these relate to the tar files).
>    

Yes, I plan on writing something up.

>> In general the best place to start is with the distro provided packages.
>>
>>      
> My distro (Debian) is only at 85, even in unstable.  Since it wasn't
> current, and also the dependencies will have wide effects on my system
> (which I'm trying to keep at the stable release Lenny), I figured
> getting the current source and building it myself would be the best
> move.  For other reasons I'm already running a 2.6.30 kernel from
> Debian, which includes kernel side kvm.  So I figure I only need to mess
> with user space.
>    

Right, stick with your kernel's kvm.ko, qemu-kvm-0.11.0 should make a 
good fit.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

Re: kvm or qemu-kvm?

[Jim Paris]

Ross Boylan wrote:
> My distro (Debian) is only at 85, even in unstable.  Since it wasn't
> current, and also the dependencies will have wide effects on my system
> (which I'm trying to keep at the stable release Lenny), I figured
> getting the current source and building it myself would be the best
> move.  For other reasons I'm already running a 2.6.30 kernel from
> Debian, which includes kernel side kvm.  So I figure I only need to mess
> with user space.

That's what I do.  Just as a warning, if you're using the libvirt
packages from Debian unstable, make sure you also install
linux-libc-dev from unstable before building qemu-kvm.

Otherwise, virtio networking will fail.  The reason is that qemu-kvm
will be built against the Lenny linux-libc-dev which does not have
IFF_VNET_HDR, while the libvirt was built against a newer
linux-libc-dev that did define IFF_VNET_HDR.  If they don't agree then
things break.

(just had to track this one down the other day)

-jim

Re: kvm or qemu-kvm?

[Avi Kivity]

On 10/01/2009 08:06 PM, Jim Paris wrote:
> That's what I do.  Just as a warning, if you're using the libvirt
> packages from Debian unstable, make sure you also install
> linux-libc-dev from unstable before building qemu-kvm.
>
> Otherwise, virtio networking will fail.  The reason is that qemu-kvm
> will be built against the Lenny linux-libc-dev which does not have
> IFF_VNET_HDR, while the libvirt was built against a newer
> linux-libc-dev that did define IFF_VNET_HDR.  If they don't agree then
> things break.
>    

Isn't that a libvirt bug?  libvirt shouldn't assume qemu supports 
IFF_VNET_HDR just because it sees it.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

Re: kvm or qemu-kvm?

[Jim Paris]

Avi Kivity wrote:
> On 10/01/2009 08:06 PM, Jim Paris wrote:
>> That's what I do.  Just as a warning, if you're using the libvirt
>> packages from Debian unstable, make sure you also install
>> linux-libc-dev from unstable before building qemu-kvm.
>>
>> Otherwise, virtio networking will fail.  The reason is that qemu-kvm
>> will be built against the Lenny linux-libc-dev which does not have
>> IFF_VNET_HDR, while the libvirt was built against a newer
>> linux-libc-dev that did define IFF_VNET_HDR.  If they don't agree then
>> things break.
>
> Isn't that a libvirt bug?  libvirt shouldn't assume qemu supports  
> IFF_VNET_HDR just because it sees it.

Probably, but I think it has no way of knowing, because qemu doesn't
report whether it supports it.

  http://libvirt.org/git/?p=libvirt.git;a=commit;h=b4f62abbf1191c8fbab3306b4bf2f2567e18067f

"However, we need to be careful to only set the flag when a) QEMU has
support for this ABI and b) the value of the flag is queryable using
the TUNGETIFF ioctl.

It's nearly five months since kvm-74 - the first KVM release with this
feature - was released. Up until now, we've not added libvirt support
because there is no clean way to detect support for this in QEMU at
runtime. A brief attempt to add a "info capabilities" monitor command
to QEMU floundered. Perfect is the enemy of good enough. Probing the
KVM version will suffice for now."

-jim

Re: kvm or qemu-kvm?

[René Pfeiffer]

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On Oct 01, 2009 at 1902 +0200, Avi Kivity appeared and said:
> On 10/01/2009 06:51 PM, Ross Boylan wrote:
> >
> >My distro (Debian) is only at 85, even in unstable.  Since it wasn't
> >current, and also the dependencies will have wide effects on my system
> >(which I'm trying to keep at the stable release Lenny), I figured
> >getting the current source and building it myself would be the best
> >move.  For other reasons I'm already running a 2.6.30 kernel from
> >Debian, which includes kernel side kvm.  So I figure I only need to mess
> >with user space.
> 
> Right, stick with your kernel's kvm.ko, qemu-kvm-0.11.0 should make a
> good fit.

Just to be sure: If I use Debian Lenny with a kernel from kernel.org,
then I can use the qemu-kvm packages and be fine. Right?

Best,
René.

-- 
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 /,   _.. \   _\  (`._ ,. R. Pfeiffer <lynx at luchs.at> + http://web.luchs.at/
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Re: kvm or qemu-kvm?

[Michael Tokarev]

René Pfeiffer wrote:
> On Oct 01, 2009 at 1902 +0200, Avi Kivity appeared and said:
[]
>> Right, stick with your kernel's kvm.ko, qemu-kvm-0.11.0 should make a
>> good fit.
> 
> Just to be sure: If I use Debian Lenny with a kernel from kernel.org,
> then I can use the qemu-kvm packages and be fine. Right?

If you use kernel from kernel.org and kvm from linux-kvm.org,
there's no difference (as far as kvm is concerned) what
distribution it is.

qemu-kvm-0.11.0 works fine with stock kernels >= 2.6.28.

Speaking of debian, take a look at http://www.corpit.ru/debian/tls/kvm/ --
ready-to-install debian packages including 0.11.0.
(don't add this to sources.list)

/mjt