Hi Jiri - 

I've learned more since filing that BZ and I wrote it down in this KCS.
https://access.redhat.com/solutions/6999469

I found an obscure reference on the i440fx issue buried in the section 19.1 of the "Considerations" document. But it does not tell the whole story and 999 of 1000 people will miss it. And it says "unsupported," when older i440fx VMs flat-out will not run and the error message includes the word, "illegal." 

I also found another reference in section 4.20 of the RHEL 9 Release Notes, buried under a long bulleted list of new machine types. But that bulleted list of newly supported machine types is not accurate. Support for i440fx-RHEL7.6 first appeared with the qemu-rhev bundled with RHEL 7-based RHV and Openstack. Many of the q35-RHEL8 variants came with RHEL 8.

On SPICE - My SPICE VMs that worked on RHEL 8 before my LEAPP upgrade failed with RHEL 9 with a similar illegal configuration error about SPICE. 

NICs - I read somewhere that Intel E1000 NICs are no longer supported, but now I don't remember where. Everyone emulated the E1000 for VMs when virtio didn't work. I always use virtio NICs whenever possible anyway, so I didn't have any failed VMs from that. But the documentation should be a source of truth for any NICs that worked with earlier versions and now no longer supported or no longer work.

Thanks Jiri - 

Looks like I messed up on the word, "illegal." I see now, the operative word in the error message is "unsupported." I changed the KCS to say "invalid." Now I'm trying to figure out how "illegal" got into my head. Here is the output you asked for.

[root@storage2015 ~]# virsh start mgmtdns2015
error: Failed to start domain 'mgmtdns2015'
error: unsupported configuration: Emulator '/usr/libexec/qemu-kvm' does not support machine type 'pc-i440fx-rhel7.0.0'

[root@storage2015 ~]# virsh dumpxml mgmtdns2015 | grep 440
    <type arch='x86_64' machine='pc-i440fx-rhel7.0.0'>hvm</type>
[root@storage2015 ~]#

Here is one with the SPICE problem. I think I tried to edit it because from memory from a month+ ago, I remember a specific error message about SPICE. I probably decided editing was more trouble than it was worth after running into the next problem with qxl and just provisioned another VM.

[root@storage2015 ~]# virsh dumpxml RHVM2020-2023messedup | grep spice
    <channel type='spicevmc'>
      <target type='virtio' name='com.redhat.spice.0'/>
    <graphics type='spice' autoport='yes' listen='127.0.0.1'>
    <redirdev bus='usb' type='spicevmc'>
    <redirdev bus='usb' type='spicevmc'>
[root@storage2015 ~]#
[root@storage2015 ~]# virsh start RHVM2020-2023messedup
error: Failed to start domain 'RHVM2020-2023messedup'
error: unsupported configuration: domain configuration does not support video model 'qxl'

[root@storage2015 ~]#
[root@storage2015 ~]# virsh dumpxml RHVM2020-2023messedup | grep qxl
      <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
[root@storage2015 ~]#

I'll also take a look at the doc update drafts.

thanks!

The updates to the docs have been published on the Customer Portal: 

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html/considerations_in_adopting_rhel_9/assembly_virtualization_considerations-in-adopting-rhel-9

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html/configuring_and_managing_virtualization/assembly_feature-support-and-limitations-in-rhel-9-virtualization_configuring-and-managing-virtualization#recommended-features-in-rhel-9-virtualization_feature-support-and-limitations-in-rhel-9-virtualization

Therefore, I will be closing this BZ. If there are any other issues with the documentation, please let me know.

Cheers,
J.