> On Jul 21, 2017, at 7:40 PM, Michael S. Tsirkin <m...@redhat.com> wrote: > > 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/. >> >> 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. > > I think I'd disagree with that. If > users might need this for compatibility with some guests, > then it should be a property not just a machine type. > > But see below - I think we rushed it for the PC anyway. > >> Probably no one would worry about fixing virt-install or something >> else for the sake of w2k and if they are going to fix it >> it doesn't matter if they map machine type vs property. >> >> 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. >> >> 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. > > If I have to choose, I'd say Mac OSX is way less interesting than old > windows versions. Lots of people have software that will only run on old > windows and there's probably good money to be had running it on new > hardware in VMs. And PC machine is all about compatibility - we have Q35 > for new stuff. Besides OSX uses q35 anyway I think. > > So maybe the right thing to do is to > - switch default for PC back to rev 1 > - keep default for Q35 at rev 3 > > No machinetype hacks.
I agree with your ideas.
