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Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated |
Date: |
Fri, 26 Oct 2018 11:40:29 +0100 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
* Daniel P. Berrangé (address@hidden) wrote:
> On Fri, Oct 26, 2018 at 12:33:55PM +0530, P J P wrote:
> > Hello Dan, all
> >
> > +-- On Thu, 25 Oct 2018, Daniel P. Berrangé wrote --+
> > | On Thu, Oct 25, 2018 at 10:52:56AM +0200, Gerd Hoffmann wrote:
> > | > While being at it deprecate cirrus too.
> > | >
> > | > Reason (short version): use stdvga instead.
> > | > Verbose version:
> > | >
> > https://www.kraxel.org/blog/2014/10/qemu-using-cirrus-considered-harmful
> > |
> > |
> > | I don't debate the points in the blog post above that stdvga is a
> > | better choice, but I don't think that's enough to justify deprecating
> > | cirrus at this point in time, because when it then gets deleted it
> > | will break way too many existing deployments.
> > |
> > | We need to socialize info in that blog post above more widely and
> > | especially ensure that apps are not using that by default. I don't
> > | see it being viable to formally deprecate it in QEMU any time soon
> > | though given existing usage.
> >
> > To note, IMO there are other devices/sources in QEMU which are potential
> > candidates for deprecation, similar to adlib etc. It'll help if we could
> > device a process to deprecate/remove such code base. Other than maintenance
> > it
> > invariably also becomes source of security issues.
> >
> > Ex.(similar to Fedora) we could announce such candidate on qemu-devel list
> > and
> > after review over a period of say a month, candidate will be
> > deprecated/expunged. (thinking aloud)
>
> QEMU has a deprecation process:
>
> https://qemu.weilnetz.de/doc/qemu-doc.html#Deprecated-features
>
> Most of the stuff deprecated is CLI args / monitor commands, etc where
> mgmt apps just adjust the way they are calling QEMU, so end user's VMs
> are largely not impacted.
>
> Deprecating a device type that is widely used is not desirable because
> that will cause breakage of existing guests. Distros are free to disable
> devices in their builds if they want to reduce the scope for CVEs in
> packages they maintain, but again they should think carefully about how
> many users they are going to break by doing so.
I'm a bit mixed here; until recent guest kernels I've always treated
Cirrus as the 'safe' one that's likely to work on anything - so losing
it worries me. Having said that, I understand why we want to deprecate
it; but we should give a much longer deprecation warning - a few years?
I don't see any harm warning that it's deprecated and you really should
try not to use it.
Dave
> Regards,
> Daniel
> --
> |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
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>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, (continued)
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, P J P, 2018/10/25
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, Philippe Mathieu-Daudé, 2018/10/25
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, Thomas Huth, 2018/10/25
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, Daniel P . Berrangé, 2018/10/25
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, P J P, 2018/10/26
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, Daniel P . Berrangé, 2018/10/26
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, Daniel P . Berrangé, 2018/10/26
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, Paolo Bonzini, 2018/10/26
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, Daniel P . Berrangé, 2018/10/26
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, P J P, 2018/10/26
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated,
Dr. David Alan Gilbert <=
- Re: [Qemu-devel] [libvirt] [PATCH 3/3] cirrus: mark as deprecated, Christian Borntraeger, 2018/10/26
- Re: [Qemu-devel] [libvirt] [PATCH 3/3] cirrus: mark as deprecated, Cole Robinson, 2018/10/26
- Re: [Qemu-devel] [libvirt] [PATCH 3/3] cirrus: mark as deprecated, Daniel P . Berrangé, 2018/10/26
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, Gerd Hoffmann, 2018/10/29
- Re: [Qemu-devel] [PATCH 3/3] cirrus: mark as deprecated, Daniel P . Berrangé, 2018/10/30
[Qemu-devel] [PATCH 2/3] adlib: mark as insecure and deprecated., Gerd Hoffmann, 2018/10/25