[v2] buildsys: Do not build various objects if not necessary

[PATCH v2 09/12] qapi/meson: Restrict qdev code to system-mode emulation

Posted by Philippe Mathieu-Daudé 5 years ago

Beside a CPU device, user-mode emulation doesn't access
anything else from qdev subsystem.

Tools don't need anything from qdev.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
Cc: Laurent Vivier <laurent@vivier.eu>
Cc: Eduardo Habkost <ehabkost@redhat.com>
---
 stubs/qdev.c      | 23 +++++++++++++++++++++++
 MAINTAINERS       |  1 +
 qapi/meson.build  |  6 +++++-
 stubs/meson.build |  2 ++
 4 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 stubs/qdev.c

diff --git a/stubs/qdev.c b/stubs/qdev.c
new file mode 100644
index 00000000000..92e61431344
--- /dev/null
+++ b/stubs/qdev.c
@@ -0,0 +1,23 @@
+/*
+ * QOM stubs
+ *
+ * Copyright (c) 2021 Red Hat, Inc.
+ *
+ * Author:
+ *   Philippe Mathieu-Daudé <philmd@redhat.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/qapi-events-qdev.h"
+
+void qapi_event_send_device_deleted(bool has_device,
+                                    const char *device,
+                                    const char *path)
+{
+    /* Nothing to do. */
+}
diff --git a/MAINTAINERS b/MAINTAINERS
index 34359a99b8e..d2dd7c24228 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2523,6 +2523,7 @@ F: qapi/qom.json
 F: qapi/qdev.json
 F: scripts/coccinelle/qom-parent-type.cocci
 F: softmmu/qdev-monitor.c
+F: stubs/qdev.c
 F: qom/
 F: tests/check-qom-interface.c
 F: tests/check-qom-proplist.c
diff --git a/qapi/meson.build b/qapi/meson.build
index ab68e7900e4..2839871b478 100644
--- a/qapi/meson.build
+++ b/qapi/meson.build
@@ -35,7 +35,6 @@
   'misc-target',
   'net',
   'pragma',
-  'qdev',
   'pci',
   'qom',
   'rdma',
@@ -49,6 +48,11 @@
   'ui',
   'yank',
 ]
+if have_system
+  qapi_all_modules += [
+    'qdev',
+  ]
+endif
 
 qapi_storage_daemon_modules = [
   'block-core',
diff --git a/stubs/meson.build b/stubs/meson.build
index 1a656cd0704..a054d5877fb 100644
--- a/stubs/meson.build
+++ b/stubs/meson.build
@@ -53,4 +53,6 @@
 if have_system
   stub_ss.add(files('semihost.c'))
   stub_ss.add(files('xen-hw-stub.c'))
+else
+  stub_ss.add(files('qdev.c'))
 endif
-- 
2.26.2

Re: [PATCH v2 09/12] qapi/meson: Restrict qdev code to system-mode emulation

Posted by Paolo Bonzini 5 years ago

On 22/01/21 21:44, Philippe Mathieu-Daudé wrote:
> Beside a CPU device, user-mode emulation doesn't access
> anything else from qdev subsystem.
> 
> Tools don't need anything from qdev.

I prefer to avoid stubs.  So if this patch can simply be dropped with no 
effects on 10-12, that's nicer for me.

Paolo

> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> Cc: Laurent Vivier <laurent@vivier.eu>
> Cc: Eduardo Habkost <ehabkost@redhat.com>
> ---
>   stubs/qdev.c      | 23 +++++++++++++++++++++++
>   MAINTAINERS       |  1 +
>   qapi/meson.build  |  6 +++++-
>   stubs/meson.build |  2 ++
>   4 files changed, 31 insertions(+), 1 deletion(-)
>   create mode 100644 stubs/qdev.c
> 
> diff --git a/stubs/qdev.c b/stubs/qdev.c
> new file mode 100644
> index 00000000000..92e61431344
> --- /dev/null
> +++ b/stubs/qdev.c
> @@ -0,0 +1,23 @@
> +/*
> + * QOM stubs
> + *
> + * Copyright (c) 2021 Red Hat, Inc.
> + *
> + * Author:
> + *   Philippe Mathieu-Daudé <philmd@redhat.com>
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qapi/qapi-events-qdev.h"
> +
> +void qapi_event_send_device_deleted(bool has_device,
> +                                    const char *device,
> +                                    const char *path)
> +{
> +    /* Nothing to do. */
> +}
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 34359a99b8e..d2dd7c24228 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2523,6 +2523,7 @@ F: qapi/qom.json
>   F: qapi/qdev.json
>   F: scripts/coccinelle/qom-parent-type.cocci
>   F: softmmu/qdev-monitor.c
> +F: stubs/qdev.c
>   F: qom/
>   F: tests/check-qom-interface.c
>   F: tests/check-qom-proplist.c
> diff --git a/qapi/meson.build b/qapi/meson.build
> index ab68e7900e4..2839871b478 100644
> --- a/qapi/meson.build
> +++ b/qapi/meson.build
> @@ -35,7 +35,6 @@
>     'misc-target',
>     'net',
>     'pragma',
> -  'qdev',
>     'pci',
>     'qom',
>     'rdma',
> @@ -49,6 +48,11 @@
>     'ui',
>     'yank',
>   ]
> +if have_system
> +  qapi_all_modules += [
> +    'qdev',
> +  ]
> +endif
>   
>   qapi_storage_daemon_modules = [
>     'block-core',
> diff --git a/stubs/meson.build b/stubs/meson.build
> index 1a656cd0704..a054d5877fb 100644
> --- a/stubs/meson.build
> +++ b/stubs/meson.build
> @@ -53,4 +53,6 @@
>   if have_system
>     stub_ss.add(files('semihost.c'))
>     stub_ss.add(files('xen-hw-stub.c'))
> +else
> +  stub_ss.add(files('qdev.c'))
>   endif
>

Re: [PATCH v2 09/12] qapi/meson: Restrict qdev code to system-mode emulation

Posted by Philippe Mathieu-Daudé 5 years ago

On 1/23/21 7:10 PM, Paolo Bonzini wrote:
> On 22/01/21 21:44, Philippe Mathieu-Daudé wrote:
>> Beside a CPU device, user-mode emulation doesn't access
>> anything else from qdev subsystem.
>>
>> Tools don't need anything from qdev.
> 
> I prefer to avoid stubs.  So if this patch can simply be dropped with no
> effects on 10-12, that's nicer for me.

The alternative is ugly:

-- >8 --
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index cefc5eaa0a9..d09f32e38d6 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -950,7 +950,9 @@ static void device_finalize(Object *obj)
     if (dev->pending_deleted_event) {
         g_assert(dev->canonical_path);

+#ifdef CONFIG_USER_ONLY
         qapi_event_send_device_deleted(!!dev->id, dev->id,
dev->canonical_path);
+#endif
         g_free(dev->canonical_path);
         dev->canonical_path = NULL;
     }
---

Maybe wrapping it in an inlined function?

Re: [PATCH v2 09/12] qapi/meson: Restrict qdev code to system-mode emulation

Posted by Paolo Bonzini 5 years ago

On 24/01/21 01:32, Philippe Mathieu-Daudé wrote:
> 
> The alternative is ugly:
> 
> -- >8 --
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index cefc5eaa0a9..d09f32e38d6 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -950,7 +950,9 @@ static void device_finalize(Object *obj)
>      if (dev->pending_deleted_event) {
>          g_assert(dev->canonical_path);
> 
> +#ifdef CONFIG_USER_ONLY
>          qapi_event_send_device_deleted(!!dev->id, dev->id,
> dev->canonical_path);
> +#endif
>          g_free(dev->canonical_path);
>          dev->canonical_path = NULL;
>      }
> ---

Well, the alternative is also to not do anything.  There's already a 
stub for qapi_event_emit, does it really hurt to have the 
not-stubbed-out code for qapi_event_send_device_deleted?

Paolo