/usr/bin/qemu-kvm symlink

[Zbigniew Jędrzejewski-Szmek]

Hi,

I was told [1] that /usr/bin/qemu-kvm is obsolete, and that the right
thing is to use 'qemu-system-x86_64 -enable-kvm', and that Arch and
Gentoo and qemu upstream don't support /usr/bin/qemu-kvm. Fedora provides
/usr/bin/qemu-kvm as a shell wrapper on amd64 and i386 architectures.

My questions are:
1. do we plan to keep this wrapper indefinitely?
2. wouldn't it make sense to convince upstream to provide /usr/bin/qemu-kvm
   which would mean "provide accelerated emulation of current architecture"?

Non-accelerated qemu is unusable for many purposes..., and often you
just want the current architecture, so it'd be nice to have a shortcut
for that.

[1] https://github.com/systemd/systemd/pull/6138

[Daniel P. Berrange]

On Sat, Jun 17, 2017 at 05:25:18PM +0000, Zbigniew Jędrzejewski-Szmek wrote:
>  Hi,
>  
>  I was told [1] that /usr/bin/qemu-kvm is obsolete, and that the right
>  thing is to use 'qemu-system-x86_64 -enable-kvm', and that Arch and
>  Gentoo and qemu upstream don't support /usr/bin/qemu-kvm. Fedora provides
>  /usr/bin/qemu-kvm as a shell wrapper on amd64 and i386 architectures.
>  
>  My questions are:
>  1. do we plan to keep this wrapper indefinitely? 
Probably, since there's plenty of installs from older Fedora that
reference that path.

>  2. wouldn't it make sense to convince upstream to provide
> /usr/bin/qemu-kvm
>     which would mean "provide accelerated emulation of current architecture"?
>
>  Non-accelerated qemu is unusable for many purposes..., and often you
>  just want the current architecture, so it'd be nice to have a shortcut
>  for that. 
The way you configure QEMU for different architectures varies considerably,
so having a consistent binary doesn't really simply things to any great
degree, as you still have to know alot of architecture specific things to
provide a good configuration.

Tools like virt-install give a way to setup guests in a simpler manner
while hiding most of the architecture specific differences, as well as
defaulting to using KVM.

Regards,
Daniel
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[Antti Jarvinen]

Daniel P. Berrange writes:
>  The way you configure QEMU for different architectures varies
> considerably, 
Yes. Also debian 9 is missing /usr/bin/qemu-kvm while 
$ ls -l /usr/bin/qemu* | wc
     60     540    4258
$ 
which includes qemuctl, so -1.

--
Antti

[Richard W.M. Jones]

On Sat, Jun 17, 2017 at 05:25:18PM +0000, Zbigniew Jędrzejewski-Szmek wrote:
>  Hi,
>  
>  I was told [1] that /usr/bin/qemu-kvm is obsolete, and that the right
>  thing is to use 'qemu-system-x86_64 -enable-kvm', [...] 
As Dan says, use libvirt.

However I want to point out that the advice above is also wrong: The
‘-enable-kvm’ option is obsolete, and that command would only work if
you were emulating x86_64, which is by no means the only architecture
which supports KVM.  Really you should use libvirt rather than trying
to formulate qemu command lines.

>  2. wouldn't it make sense to convince upstream to provide
> /usr/bin/qemu-kvm
>     which would mean "provide accelerated emulation of current architecture"?
Possibly, but what many people want is "be as fast as you can but
don't break if KVM isn't available", which is provided by the
‘-machine accel=kvm:tcg’ option, or by using libvirt capabilities to
discover what acceleration and emulation options are available on the
current host.

Rich.

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