Fixes './configure --without-default-devices --enable-xen' build:

  /usr/bin/ld: libcommon.fa.p/hw_xen_xen-legacy-backend.c.o: in function `xen_be_register_common':
  hw/xen/xen-legacy-backend.c:754: undefined reference to `xen_9pfs_ops'
  /usr/bin/ld: libcommon.fa.p/fsdev_qemu-fsdev.c.o:(.data.rel+0x8): undefined reference to `local_ops'
  /usr/bin/ld: libcommon.fa.p/fsdev_qemu-fsdev.c.o:(.data.rel+0x20): undefined reference to `synth_ops'
  /usr/bin/ld: libcommon.fa.p/fsdev_qemu-fsdev.c.o:(.data.rel+0x38): undefined reference to `proxy_ops'
  collect2: error: ld returned 1 exit status

Fixes: b2c00bce54c ("meson: convert hw/9pfs, cleanup")
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
I'm not sure b2c00bce54c is the real culprit

Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Paul Durrant <paul@xen.org>
Cc: xen-devel@lists.xenproject.org
Cc: Greg Kurz <groug@kaod.org>
Cc: Christian Schoenebeck <qemu_oss@crudebyte.com>
---
 hw/9pfs/Kconfig     | 4 ----
 hw/9pfs/meson.build | 2 +-
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/hw/9pfs/Kconfig b/hw/9pfs/Kconfig
index d3ebd737301..3ae57496613 100644
--- a/hw/9pfs/Kconfig
+++ b/hw/9pfs/Kconfig
@@ -2,12 +2,8 @@ config FSDEV_9P
     bool
     depends on VIRTFS
 
-config 9PFS
-    bool
-
 config VIRTIO_9P
     bool
     default y
     depends on VIRTFS && VIRTIO
     select FSDEV_9P
-    select 9PFS
diff --git a/hw/9pfs/meson.build b/hw/9pfs/meson.build
index cc094262122..99be5d91196 100644
--- a/hw/9pfs/meson.build
+++ b/hw/9pfs/meson.build
@@ -15,6 +15,6 @@
   'coxattr.c',
 ))
 fs_ss.add(when: 'CONFIG_XEN', if_true: files('xen-9p-backend.c'))
-softmmu_ss.add_all(when: 'CONFIG_9PFS', if_true: fs_ss)
+softmmu_ss.add_all(when: 'CONFIG_FSDEV_9P', if_true: fs_ss)
 
 specific_ss.add(when: 'CONFIG_VIRTIO_9P', if_true: files('virtio-9p-device.c'))
-- 
2.26.2

On Wed,  4 Nov 2020 09:43:25 +0100
Philippe Mathieu-Daudé <philmd@redhat.com> wrote:

> Fixes './configure --without-default-devices --enable-xen' build:
> 
>   /usr/bin/ld: libcommon.fa.p/hw_xen_xen-legacy-backend.c.o: in function `xen_be_register_common':
>   hw/xen/xen-legacy-backend.c:754: undefined reference to `xen_9pfs_ops'
>   /usr/bin/ld: libcommon.fa.p/fsdev_qemu-fsdev.c.o:(.data.rel+0x8): undefined reference to `local_ops'
>   /usr/bin/ld: libcommon.fa.p/fsdev_qemu-fsdev.c.o:(.data.rel+0x20): undefined reference to `synth_ops'
>   /usr/bin/ld: libcommon.fa.p/fsdev_qemu-fsdev.c.o:(.data.rel+0x38): undefined reference to `proxy_ops'
>   collect2: error: ld returned 1 exit status
> 
> Fixes: b2c00bce54c ("meson: convert hw/9pfs, cleanup")
> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> I'm not sure b2c00bce54c is the real culprit
> 

FWIW this commit introduced the 9PFS config which isn't used
anywhere. Backends depend on FSDEV_9P which itself depends
on VIRTFS. So I tend to think b2c00bce54c is the culprit
but _of couse_ I could be wrong :)

Anyway, this patch (+ patch 1) fix the build break mentioned
in the changelog so:

Acked-by: Greg Kurz <groug@kaod.org>
Tested-by: Greg Kurz <groug@kaod.org>

> Cc: Stefano Stabellini <sstabellini@kernel.org>
> Cc: Anthony Perard <anthony.perard@citrix.com>
> Cc: Paul Durrant <paul@xen.org>
> Cc: xen-devel@lists.xenproject.org
> Cc: Greg Kurz <groug@kaod.org>
> Cc: Christian Schoenebeck <qemu_oss@crudebyte.com>
> ---
>  hw/9pfs/Kconfig     | 4 ----
>  hw/9pfs/meson.build | 2 +-
>  2 files changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/hw/9pfs/Kconfig b/hw/9pfs/Kconfig
> index d3ebd737301..3ae57496613 100644
> --- a/hw/9pfs/Kconfig
> +++ b/hw/9pfs/Kconfig
> @@ -2,12 +2,8 @@ config FSDEV_9P
>      bool
>      depends on VIRTFS
>  
> -config 9PFS
> -    bool
> -
>  config VIRTIO_9P
>      bool
>      default y
>      depends on VIRTFS && VIRTIO
>      select FSDEV_9P
> -    select 9PFS
> diff --git a/hw/9pfs/meson.build b/hw/9pfs/meson.build
> index cc094262122..99be5d91196 100644
> --- a/hw/9pfs/meson.build
> +++ b/hw/9pfs/meson.build
> @@ -15,6 +15,6 @@
>    'coxattr.c',
>  ))
>  fs_ss.add(when: 'CONFIG_XEN', if_true: files('xen-9p-backend.c'))
> -softmmu_ss.add_all(when: 'CONFIG_9PFS', if_true: fs_ss)
> +softmmu_ss.add_all(when: 'CONFIG_FSDEV_9P', if_true: fs_ss)
>  
>  specific_ss.add(when: 'CONFIG_VIRTIO_9P', if_true: files('virtio-9p-device.c'))

On 04/11/20 09:43, Philippe Mathieu-Daudé wrote:
> Fixes './configure --without-default-devices --enable-xen' build:
> 
>    /usr/bin/ld: libcommon.fa.p/hw_xen_xen-legacy-backend.c.o: in function `xen_be_register_common':
>    hw/xen/xen-legacy-backend.c:754: undefined reference to `xen_9pfs_ops'
>    /usr/bin/ld: libcommon.fa.p/fsdev_qemu-fsdev.c.o:(.data.rel+0x8): undefined reference to `local_ops'
>    /usr/bin/ld: libcommon.fa.p/fsdev_qemu-fsdev.c.o:(.data.rel+0x20): undefined reference to `synth_ops'
>    /usr/bin/ld: libcommon.fa.p/fsdev_qemu-fsdev.c.o:(.data.rel+0x38): undefined reference to `proxy_ops'
>    collect2: error: ld returned 1 exit status
> 
> Fixes: b2c00bce54c ("meson: convert hw/9pfs, cleanup")
> Suggested-by: Paolo Bonzini<pbonzini@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé<philmd@redhat.com>
> ---
> I'm not sure b2c00bce54c is the real culprit

I think it is, probably a wrong conflict resolution.

Paolo