Re: [PATCH 01/10] hw/s390x/s390-virtio-ccw: Remove the deprecated 2.4 and 2.5 machine types

[Cornelia Huck]

On Fri, Jan 03 2025, Thomas Huth <thuth@redhat.com> wrote:

> They are older than 6 years, so according to our machine support
> policy, they can be removed now.
>
> This removes the requirements for the storage keys "migration-enabled"
> property which will be removed in the next patch. It also removes
> the code that sets "max_revision" to 0 for some CCW devices, but
> the relating code in virtio-ccw.c indicates that 0 could have also
> been in use for other machines types < 5.1, so further clean-up for
> code related to "max_revision" won't be done yet.

These are two different issues:
- QEMU 2.4 and earlier _defaulted_ to legacy virtio devices (enforced by
  setting max_revision to 0)
- QEMU 5.0 and earlier _allowed_ virtio device types to be configured as
  legacy devices that did not actually support legacy (e.g. virtio-gpu),
  there's a compat value to allow a max_revision of 0 for those old
  machine types

So that's not a problem -- but I wonder whether we had missed the boat
elsewhere, when we introduced revisions > 1 (nothing much we can do now
if that is the case, though.)

I also don't think we actually want to remove max_revision anyway, as it
could also be used for non-compat related things (e.g. to accommodate a
known buggy driver.)

>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  hw/s390x/s390-virtio-ccw.c | 37 -------------------------------------
>  1 file changed, 37 deletions(-)

The patch itself LGTM.