Re: [Qemu-devel] [PATCH] compat: Use explicit type names on HW_COMPAT_2_6

[Cornelia Huck <cohuck@redhat.com>]

On Fri,  4 Jan 2019 01:22:26 -0200
Eduardo Habkost <ehabkost@redhat.com> wrote:

> The virtio-pci entries in HW_COMPAT_2_6 had an implicit
> assumption: that all virtio-pci subclasses support the
> disable-legacy and disable-modern options.
> 
> That assumption was broken by commit f6e501a28ef9 ("virtio:
> Provide version-specific variants of virtio PCI devices").  This
> caused QEMU to crash if using the new -non-transitional or
> -transitional device types:
> 
>   $ qemu-system-x86_64 -machine pc-i440fx-2.6 \
>     -device virtio-net-pci-non-transitional
>   Unexpected error in object_property_find() at qom/object.c:1092:
>   qemu-system-x86_64: -device virtio-net-pci-non-transitional: can't apply \
>   global virtio-pci.disable-modern=on: Property '.disable-modern' not found
>   Aborted (core dumped)
> 
> Replace the virtio-pci.disable-legacy=off and
> virtio-pci.disable-modern=on entries on HW_COMPAT_2_6 with
> explicit entries for each generic virtio device type.
> 
> The full list of generic virtio device types was extracted by
> just grepping for ".generic_name".  Note that we don't need to
> worry about listing new virtio-pci devices in HW_COMPAT_2_6 in
> the future, because new devices won't require QEMU 2.6
> compatibility.

Some of these will not be relevant for 2.6 compat, but better safe than
sorry :)

> 
> This makes the compat entries annoyingly verbose, but is simpler
> than the alternative of making the virtio-pci type inheritance
> rules even more complex.

Maybe also write out explicitly:

Fixes: f6e501a28ef9 ("virtio: Provide version-specific variants of virtio PCI devices")

> 
> Reported-by: Thomas Huth <thuth@redhat.com>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
> ---
>  include/hw/compat.h | 140 +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 138 insertions(+), 2 deletions(-)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>