Re: [Qemu-devel] [PATCH 21/26] build-sys: make qemu qapi objects per-target

[Markus Armbruster <armbru@redhat.com>]

Marc-André Lureau <marcandre.lureau@redhat.com> writes:

> The qapi schema has per-target definitions. Move qapi objects in the
> per-target build, so they can be configured at compile time.

Suggest something like:

    QAPI can't do target-specific conditionals (the symbols are
    poisoned), and the work-around is to pretend the target-specific
    stuff is target-independent, with stubs for the other targets.
    Makes the target-specifity invisible in introspection.

    To unpoison the symbols, we need to move the generated QAPI code to
    the per-target build.

> Keep qapi-types.o qapi-visit.o in util-obj as they are necessary for
> common code, but they will be overwritten during the target link.

--verbose: how are they supposed to even compile in the
target-independent build once we generate #if defined(TARGET_FOO) into
them?

>                                                                   Add
> some stubs for block events, in code shared by tools & qemu.

Sounds awkward.

> The following patch will configure the schema to conditionally remove
> per-target disabled features.

"The following patches", right?

> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  stubs/qapi-event.c                 | 74 ++++++++++++++++++++++++++++++++++++++
>  tests/test-qobject-input-visitor.c |  1 -
>  Makefile.objs                      |  9 +----
>  Makefile.target                    |  4 +++
>  stubs/Makefile.objs                |  1 +
>  trace/Makefile.objs                |  2 +-
>  6 files changed, 81 insertions(+), 10 deletions(-)
>  create mode 100644 stubs/qapi-event.c
>
> diff --git a/stubs/qapi-event.c b/stubs/qapi-event.c
> new file mode 100644
> index 0000000000..9415299f3a
> --- /dev/null
> +++ b/stubs/qapi-event.c
> @@ -0,0 +1,74 @@
> +#include "qemu/osdep.h"
> +#include "qapi-event.h"
> +
> +void qapi_event_send_device_tray_moved(const char *device, const char *id,
> +                                       bool tray_open, Error **errp)
> +{
> +}
> +
> +void qapi_event_send_quorum_report_bad(QuorumOpType type, bool has_error,
> +                                       const char *error, const char *node_name,
> +                                       int64_t sector_num,
> +                                       int64_t sectors_count, Error **errp)
> +{
> +}
> +
> +void qapi_event_send_quorum_failure(const char *reference, int64_t sector_num,
> +                                    int64_t sectors_count, Error **errp)
> +{
> +}
> +
> +void qapi_event_send_block_job_cancelled(BlockJobType type, const char *device,
> +                                         int64_t len, int64_t offset,
> +                                         int64_t speed, Error **errp)
> +{
> +}
> +
> +void qapi_event_send_block_job_completed(BlockJobType type, const char *device,
> +                                         int64_t len, int64_t offset,
> +                                         int64_t speed, bool has_error,
> +                                         const char *error, Error **errp)
> +{
> +}
> +
> +void qapi_event_send_block_job_error(const char *device,
> +                                     IoOperationType operation,
> +                                     BlockErrorAction action, Error **errp)
> +{
> +}
> +
> +void qapi_event_send_block_job_ready(BlockJobType type, const char *device,
> +                                     int64_t len, int64_t offset, int64_t speed,
> +                                     Error **errp)
> +{
> +}
> +
> +void qapi_event_send_block_io_error(const char *device, const char *node_name,
> +                                    IoOperationType operation,
> +                                    BlockErrorAction action, bool has_nospace,
> +                                    bool nospace, const char *reason,
> +                                    Error **errp)
> +{
> +}
> +
> +void qapi_event_send_block_image_corrupted(const char *device,
> +                                           bool has_node_name,
> +                                           const char *node_name,
> +                                           const char *msg, bool has_offset,
> +                                           int64_t offset, bool has_size,
> +                                           int64_t size, bool fatal,
> +                                           Error **errp)
> +{
> +}
> +
> +void qapi_event_send_block_write_threshold(const char *node_name,
> +                                           uint64_t amount_exceeded,
> +                                           uint64_t write_threshold,
> +                                           Error **errp)
> +{
> +}
> +
> +void qapi_event_send_device_deleted(bool has_device, const char *device,
> +                                    const char *path, Error **errp)
> +{
> +}

Yup, awkward.

> diff --git a/tests/test-qobject-input-visitor.c b/tests/test-qobject-input-visitor.c
> index 4da5d02c35..0a9352c5c1 100644
> --- a/tests/test-qobject-input-visitor.c
> +++ b/tests/test-qobject-input-visitor.c
> @@ -1266,7 +1266,6 @@ static void test_visitor_in_qmp_introspect(TestInputVisitorData *data,
>                                             const void *unused)
>  {
>      do_test_visitor_in_qmp_introspect(data, &test_qmp_schema_qlit);
> -    do_test_visitor_in_qmp_introspect(data, &qmp_schema_qlit);
>  }
>  
>  int main(int argc, char **argv)

Either squash this change into PATCH 20, or mention it in the commit
message.

See also my review of PATCH 04.

> diff --git a/Makefile.objs b/Makefile.objs
> index 24a4ea08b8..2664720f9b 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -2,7 +2,7 @@
>  # Common libraries for tools and emulators
>  stub-obj-y = stubs/ crypto/
>  util-obj-y = util/ qobject/ qapi/
> -util-obj-y += qmp-introspect.o qapi-types.o qapi-visit.o qapi-event.o
> +util-obj-y += qapi-types.o qapi-visit.o
>  
>  chardev-obj-y = chardev/
>  
> @@ -72,13 +72,6 @@ common-obj-y += chardev/
>  common-obj-$(CONFIG_SECCOMP) += qemu-seccomp.o
>  
>  common-obj-$(CONFIG_FDT) += device_tree.o
> -
> -######################################################################
> -# qapi
> -
> -common-obj-y += qmp-marshal.o
> -common-obj-y += qmp-introspect.o
> -common-obj-y += qmp.o hmp.o
>  endif
>  
>  #######################################################################
> diff --git a/Makefile.target b/Makefile.target
> index 2baec9252f..a97dd056ad 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -154,6 +154,10 @@ endif
>  
>  GENERATED_FILES += hmp-commands.h hmp-commands-info.h
>  
> +obj-y += qmp-introspect.o qapi-types.o qapi-visit.o qapi-event.o
> +obj-y += qmp-marshal.o qmp-introspect.o
> +obj-y += qmp.o hmp.o
> +

Moving so much code from "compile once" to "compile per target" is kind
of sad.  With the full series applied, I see

    $ wc qapi*c qmp*c
       1528    3089   34576 qapi-event.c
       5097    9126  107004 qapi-types.c
      18848   44862  469514 qapi-visit.c
      12407   32395  404704 qmp-introspect.c
       6883   14997  182063 qmp-marshal.c
      44763  104469 1197861 total

Is there any way to split stuff so we recompile less?  Note that this is
a valid question even without your patches: changing one little thing in
the QAPI schema commonly triggers a lengthy recompile.  In large part
because our undisciplined use of #include.  But also because the
generator's output is monolithic.

I'm not expecting you to answer this question now, I just want to toss
it out :)

>  endif # CONFIG_SOFTMMU
>  
>  # Workaround for http://gcc.gnu.org/PR55489, see configure.
> diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
> index f5b47bfd74..1b2bef99c9 100644
> --- a/stubs/Makefile.objs
> +++ b/stubs/Makefile.objs
> @@ -21,6 +21,7 @@ stub-obj-y += machine-init-done.o
>  stub-obj-y += migr-blocker.o
>  stub-obj-y += monitor.o
>  stub-obj-y += notify-event.o
> +stub-obj-y += qapi-event.o
>  stub-obj-y += qtest.o
>  stub-obj-y += replay.o
>  stub-obj-y += runstate-check.o
> diff --git a/trace/Makefile.objs b/trace/Makefile.objs
> index afd571c3ec..6447729d60 100644
> --- a/trace/Makefile.objs
> +++ b/trace/Makefile.objs
> @@ -56,4 +56,4 @@ util-obj-$(CONFIG_TRACE_SIMPLE) += simple.o
>  util-obj-$(CONFIG_TRACE_FTRACE) += ftrace.o
>  util-obj-y += control.o
>  target-obj-y += control-target.o
> -util-obj-y += qmp.o
> +target-obj-y += qmp.o