[libvirt] [PATCH] qemu: Warn verbosely if using old loader:nvram pairs

[Daniel P. Berrangé]

On Thu, Nov 14, 2019 at 03:26:33PM +0100, Michal Privoznik wrote:
> On 11/13/19 7:59 PM, Jim Fehlig wrote:
> > On 11/13/19 9:20 AM, Michal Privoznik wrote:
> > > On 11/12/19 11:17 PM, Jim Fehlig wrote:
> > > > On 11/11/19 9:42 AM, Michal Privoznik wrote:
> > > > > There are two ways for specifying loader:nvram pairs:
> > > > > 
> > > > >      1) --with-loader-nvram configure option
> > > > >      2) nvram variable in qemu.conf
> > > > > 
> > > > > Since we have FW descriptors, using this old style is
> > > > > discouraged, but not as strong as one would expect. Produce more
> > > > > warnings:
> > > > 
> > > > Oh, I didn't know the old style was discouraged when using FW descriptors.
> > > > Thanks for mentioning it!
> > > > 
> > > > > 
> > > > >      1) produce a warning if somebody tries the configure option
> > > > >      2) produce a warning if somebody sets nvram variable and at
> > > > >         least on FW descriptor was found
> > > > > 
> > > > > The reason for producing warning in case 1) is that package
> > > > > maintainers, who set the configure option in the first place
> > > > > should start moving towards FW descriptors and abandon the
> > > > > configure option. After all, the warning is printed into config
> > > > > output only in this case.
> > > > 
> > > > Should the configure option be removed from the upstream spec file?
> > > 
> > > Definitely, Fedora ships FW descriptors and so does RHEL. What's the state in
> > > OpenSUSE? But I bet you have your own spec file anyway, don't you? Just like we
> > > have for Fedora and RHEL. Will post a patch tomorrow (unless you beat me to it).
> > 
> > I was attempting to beat you to it, but removing $LOADERS from the spec file
> > means removing use of --with-loader-nvram configure option. Does that mean we
> > should remove associated code from configure.ac, nuke m4/virt-loader-nvram.m4,
> > remove DEFAULT_LOADER_NVRAM from qemu and libxl drivers, ...? It seems a bit
> > early for that since you are just now adding the deprecation warning to
> > virt-loader-nvram.m4 :-). Should we wait until completely removing support for
> > the build-time FW list before nuking from the spec file?
> 
> I think it's safe to remove the configure argument from the spec file, but
> at this point I'd rather wait and give distros a while to adapt to FW
> descriptors before removing the argument even from configure script. I mean,
> I can see us removing the argument and nvram=[] from qemu.conf at the same
> time, but not right now.

As long as we aim to support QEMU versions (aka our QEMU min version in
caps probing) that pre-date the FW descriptor spec, we shouldn't remove
support for this from our configure script.

Removing it from the RPM spec is fine since thd spec assumes recent Fedora
or RHEL only which both have FW descriptor support.

Regards,
Daniel
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