Re: [Qemu-devel] [libvirt] [PATCH 3/3] cirrus: mark as deprecated
On 10/26/2018 11:42 AM, Daniel P. Berrangé 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 agree with what Daniel said. Deprecating something that is in heavy use by users just because we have trouble maintaining it not going to help the QEMU project - quite the opposite.
Re: [Qemu-devel] [libvirt] [PATCH 3/3] cirrus: mark as deprecated
On Fri, Oct 26, 2018 at 09:48:35AM +0100, Cole Robinson wrote: > On 10/25/2018 09:37 PM, 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 > > > > Every single one of my guests is using cirrus. This wasn't an explicit > > choice on my part, so I believe it is being used as the default in > > virt-install. > > > > virt-manager/virt-install 2.0.0 will never explicitly set cirrus, but that > release is quite new. The previous release's default for x86 was roughly: > > if using spice graphics: > use qxl > elif guest os is windows: > use vga > else: > use cirrus > > It was definitely sub optimal. Maybe your virt-install commands were > explicitly setting --graphics vnc which would trigger cirrus in that case. Yep, I've always tended to use vnc, since QXL has historically been a pretty buggy & unreliable device model with guests often breaking. Regards, Daniel -- |: https://berrange.com -o-https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o-https://fstop138.berrange.com :| |: https://entangle-photo.org-o-https://www.instagram.com/dberrange :|
Re: [Qemu-devel] [libvirt] [PATCH 3/3] cirrus: mark as deprecated
On 10/25/2018 09:37 PM, 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 Every single one of my guests is using cirrus. This wasn't an explicit choice on my part, so I believe it is being used as the default in virt-install. virt-manager/virt-install 2.0.0 will never explicitly set cirrus, but that release is quite new. The previous release's default for x86 was roughly: if using spice graphics: use qxl elif guest os is windows: use vga else: use cirrus It was definitely sub optimal. Maybe your virt-install commands were explicitly setting --graphics vnc which would trigger cirrus in that case. 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.
