Re: [PATCH] hw/virtio: Also include md stubs in case CONFIG_VIRTIO_PCI is not set

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 13/3/25 07:35, Thomas Huth wrote:
> For the s390x target, it's possible to build the QEMU binary without
> CONFIG_VIRTIO_PCI and only have the virtio-mem device via the ccw
> transport. In that case, QEMU currently fails to link correctly:
> 
>   /usr/bin/ld: libqemu-s390x-softmmu.a.p/hw_s390x_s390-virtio-ccw.c.o: in function `s390_machine_device_pre_plug':
>   ../hw/s390x/s390-virtio-ccw.c:579:(.text+0x1e96): undefined reference to `virtio_md_pci_pre_plug'
>   /usr/bin/ld: libqemu-s390x-softmmu.a.p/hw_s390x_s390-virtio-ccw.c.o: in function `s390_machine_device_plug':
>   ../hw/s390x/s390-virtio-ccw.c:608:(.text+0x21a4): undefined reference to `virtio_md_pci_plug'
>   /usr/bin/ld: libqemu-s390x-softmmu.a.p/hw_s390x_s390-virtio-ccw.c.o: in function `s390_machine_device_unplug_request':
>   ../hw/s390x/s390-virtio-ccw.c:622:(.text+0x2334): undefined reference to `virtio_md_pci_unplug_request'
>   /usr/bin/ld: libqemu-s390x-softmmu.a.p/hw_s390x_s390-virtio-ccw.c.o: in function `s390_machine_device_unplug':
>   ../hw/s390x/s390-virtio-ccw.c:633:(.text+0x2436): undefined reference to `virtio_md_pci_unplug'
>   clang: error: linker command failed with exit code 1 (use -v to see invocation)
> 
> We also need to include the stubs when CONFIG_VIRTIO_PCI is missing.
> 
> Fixes: aa910c20ec5 ("s390x: virtio-mem support")
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>   hw/virtio/meson.build | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
> index a5f9f7999dd..cdb1836580d 100644
> --- a/hw/virtio/meson.build
> +++ b/hw/virtio/meson.build
> @@ -89,7 +89,8 @@ specific_virtio_ss.add_all(when: 'CONFIG_VIRTIO_PCI', if_true: virtio_pci_ss)
>   system_ss.add_all(when: 'CONFIG_VIRTIO', if_true: system_virtio_ss)
>   system_ss.add(when: 'CONFIG_VIRTIO', if_false: files('vhost-stub.c'))
>   system_ss.add(when: 'CONFIG_VIRTIO', if_false: files('virtio-stub.c'))
> -system_ss.add(when: 'CONFIG_VIRTIO_MD', if_false: files('virtio-md-stubs.c'))
> +system_ss.add(when: ['CONFIG_VIRTIO_MD', 'CONFIG_VIRTIO_PCI'],
> +              if_false: files('virtio-md-stubs.c'))

if_false could be tricky.

https://mesonbuild.com/SourceSet-module.html

   source_set.add([when: varnames_and_deps],
                  [if_true: sources_and_deps],
                  [if_false: list_of_alt_sources])

   If all the strings evaluate to true and all dependencies are
   found, the rule will evaluate to true; ...
   Otherwise, that is if any of the strings in the positional
   arguments evaluate to false or any dependency is not found,
   use the contents of the if_false keyword argument.

I wanted to confirm true:ALL, false:ANY. Change LGTM then:
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>