On Fri, Jul 21, 2017 at 12:10:48PM +0200, Igor Mammedov wrote: > On Fri, 21 Jul 2017 10:49:55 +0100 > "Daniel P. Berrange" <berra...@redhat.com> wrote: > > > On Fri, Jul 21, 2017 at 11:32:11AM +0200, Igor Mammedov wrote: > > > w2k used to boot on QEMU until we bumped revision of FADT to rev3 > > > (commit 77af8a2b hw/i386: Use Rev3 FADT (ACPI 2.0) instead of Rev1 to > > > improve guest OS support.) > > > > > > Considering that w2k is ancient and long time EOLed, leave default > > > rev3 but make pc-i440fx-2.9 and older machine types to force rev1 > > > so old setups won't break (w2k could boot). > > > > There needs to be a machine type property added to control this > > feature. When provisioning new VMs, management apps need to be > > able to set the property explicitly - having them rely on picking > > particular machine type name+versions is not viable, because > > downstream vendors replace the machine types with their own > > names + versions. > having property doesn't really help here and we don't do it for every > compat tweak /ex: save_tsc_khz, linuxboot_dma_enabled/.
If those compat tweaks affect compatibility with particular guest OS then they should definitely be exposed as properties too. > Management would not benefit much from having property vs machine version > as it would have to encode somewhere that for w2k it should set > some machine property or pick a particular machine type. It *would* be a significant benefit - property names are stable, machine type versions are not stable becasue downstream vendors change them. > Also with new machine type deprecation policy we would be able > easily to phase out rev1 support along with 2.9 machine, > but if you expose property then removing it would break > CLI not only for 2.9 but possible later machines if it's set there. We have the freedom to deprecate properties too if they become a significant burden. If removing machine types prevents us running certain guest OS, because we don't have a property to override, that would be a mark against removing the machine types at all IMHO. > So I'm against adding properties/CLI options for unless we have to in this > case, and I'm not convinced that w2k deserves it. w2k is just one OS that we happen to know of that breaks - who knows how many others suffer the same fate. So making decisions based on whether you care about a specific OS is flawed IMHO. 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 :|
