[rdo-dev] qemu-kvm vs qemu-kvm-rhev requirement

[Kashyap Chamarthy]

On Tue, Jun 05, 2018 at 10:24:03AM +0100, Daniel P. Berrangé wrote:
> On Tue, Jun 05, 2018 at 12:18:59PM +0300, Roman Kagan wrote:

[...]

> > This is exactly my problem: you're mixing up two separate things, the
> > QEMU version (vendor-neutral) and the features that can only be found in
> > the vendor-specific package, and I'm struggling to understand which one
> > is the deal-breaker.
> > 
> > E.g. if I try to install Nova from
> > http://mirror.centos.org/centos/7/cloud/x86_64/openstack-ocata/ on my
> > Fedora28 machine, I have no way to satisfy this qemu-kvm-rhev
> > dependency, even though qemu-kvm installed is at version 2.11.1.
> > 
> > Is this the intended behavior?
> 
> In this case we don't care, because mixing distros is explicitly
> unsupported. ie you can't expect RPMs build for CentOS7 to be able
> to successfully dep-solve against RPMs biuld for Fedora 28. If it
> ever worked, it is purely by luck not design.
> 
> IIUC, RDO project explicitly dropped support for running on Fedora
> and only targets CentOS or RHEL.

Yes, that is my understanding as well.  It was largely dropped to
little-to-no testing on Fedora.  And most testing done on CentOS and
RHEL.

> > If it is, and Nova can only be used with this very special QEMU built
> > for RHEV, what are the specific features I should be looking out for to
> > be able to produce a compatible build?  E.g. we (Virtuozzo) ship QEMU
> > package based on approximately the same mainline QEMU version as RHEV
> > but with different downstream patches and configuration.  Is it likely
> > not to work with Nova?
> 
> The qemu-kvm-rhev build is not really special - in fact it is probably
> more "normal" than the 'qemu-kvm' build because it is a modern QEMU
> version and so has relatively few patches backported, compared to the
> ancient 1.5.3 which has a load of patches backported.
> 
> So if you have a QEMU build of comparable vintage to qemu-kvm-rhev
> that would likely work. You can then solve the deps problem by adding
> a virtual  "Provides: qemu-kvm-ev = X.Y.Z"

Yep, because the CentOS package is called: 'qemu-kvm-ev'.  Also you
(Roman) might want to refer to the following note in the RDO Git/master
'openstack-nova.spec' (the RPM spec):

    # NOTE-1: CentOS package is called 'qemu-kvm-ev', but it has a                                                                                                                            
    #         compatiblity "Provides: qemu-kvm-rhev", so it'll do the                                                                                                                         
    #         right thing, that's why we're not special-casing CentOS                                                                                                                         
    #         here.                                                                                                                                                                           

So, even if you're using CentOS, and are trying to install
'qemu-kvm-rhev', it should do the Right Thing.

-- 
/kashyap