Re: [Qemu-devel] [PATCH 7/7] rdmacm-mux: convert to Meson

[Markus Armbruster <armbru@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> We can use config-host.mak to decide whether the tool has to be built,
> apart from that the conversion is straightforward.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  .gitignore                       | 1 +
>  Makefile                         | 5 -----
>  Makefile.objs                    | 1 -
>  contrib/rdmacm-mux/Makefile.objs | 3 ---
>  contrib/rdmacm-mux/meson.build   | 6 ++++++
>  meson.build                      | 2 ++
>  6 files changed, 9 insertions(+), 9 deletions(-)
>  delete mode 100644 contrib/rdmacm-mux/Makefile.objs
>  create mode 100644 contrib/rdmacm-mux/meson.build
>
> diff --git a/.gitignore b/.gitignore
> index 3934eff..b8d38a8 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -63,6 +63,7 @@
>  /qemu-version.h.tmp
>  /module_block.h
>  /scsi/qemu-pr-helper
> +/contrib/rdmacm-mux/rdmacm-mux
>  /contrib/vhost-user-scsi/vhost-user-scsi
>  /contrib/vhost-user-blk/vhost-user-blk
>  /fsdev/virtfs-proxy-helper
> diff --git a/Makefile b/Makefile
> index bff097c..713f301 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -425,7 +425,6 @@ dummy := $(call unnest-vars,, \
>                  elf2dmp-obj-y \
>                  ivshmem-client-obj-y \
>                  ivshmem-server-obj-y \
> -                rdmacm-mux-obj-y \
>                  vhost-user-input-obj-y \
>                  vhost-user-gpu-obj-y \
>                  qga-vss-dll-obj-y \
> @@ -629,10 +628,6 @@ ivshmem-server$(EXESUF): $(ivshmem-server-obj-y) $(COMMON_LDADDS)
>  	$(call LINK, $^)
>  endif
>  
> -rdmacm-mux$(EXESUF): LIBS += "-libumad"
> -rdmacm-mux$(EXESUF): $(rdmacm-mux-obj-y) $(COMMON_LDADDS)
> -	$(call LINK, $^)
> -

Another way to pass extra flags to the compiler: target-specific
variables.  More direct than the funny variables we saw in the previous
patch.

The fine manual describes a way how to shoot yourself in the foot with
target-specific variabes.  Been there, done that, had "fun" debugging.

>  vhost-user-gpu$(EXESUF): $(vhost-user-gpu-obj-y) contrib/libvhost-user/libvhost-user.a
>  	$(call LINK, $^)
>  
> diff --git a/Makefile.objs b/Makefile.objs
> index adf2f92..cf02f63 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -116,7 +116,6 @@ qga-vss-dll-obj-y = qga/
>  elf2dmp-obj-y = contrib/elf2dmp/
>  ivshmem-client-obj-$(CONFIG_IVSHMEM) = contrib/ivshmem-client/
>  ivshmem-server-obj-$(CONFIG_IVSHMEM) = contrib/ivshmem-server/
> -rdmacm-mux-obj-y = contrib/rdmacm-mux/
>  vhost-user-input-obj-y = contrib/vhost-user-input/
>  vhost-user-gpu-obj-y = contrib/vhost-user-gpu/
>  
> diff --git a/contrib/rdmacm-mux/Makefile.objs b/contrib/rdmacm-mux/Makefile.objs
> deleted file mode 100644
> index 3df744a..0000000
> --- a/contrib/rdmacm-mux/Makefile.objs
> +++ /dev/null
> @@ -1,3 +0,0 @@
> -ifdef CONFIG_PVRDMA
> -rdmacm-mux-obj-y = main.o
> -endif
> diff --git a/contrib/rdmacm-mux/meson.build b/contrib/rdmacm-mux/meson.build
> new file mode 100644
> index 0000000..8451756
> --- /dev/null
> +++ b/contrib/rdmacm-mux/meson.build
> @@ -0,0 +1,6 @@
> +if config_host['CONFIG_PVRDMA'] == 'y'
> +  # if not found, CONFIG_PVRDMA should not be set

Our Makefiles use "either unset or 'y'" booleans pretty pervasively.  Is
it idiomatic meson?

> +  libumad = cc.find_library('ibumad', required: true)

With configure & make, we have configure check -libumad works, and make
use it.

Ignorant question: cc.find_library() looks like it checks.  Could this
replace checking in configure?

> +  executable('rdmacm-mux', files('main.c'),
> +             dependencies: [glib, libumad])
> +endif
> diff --git a/meson.build b/meson.build
> index bc7fbea..2fc6111 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -1,4 +1,5 @@
>  project('qemu', 'c', meson_version: '>=0.50.999')
> +cc = meson.get_compiler('c')
>  
>  kconfig = import('unstable-kconfig')
>  config_host = kconfig.load(meson.current_build_dir() / 'config-host.mak')
> @@ -14,5 +15,6 @@ libiscsi = declare_dependency(compile_args: config_host['LIBISCSI_CFLAGS'].split
>                            link_args: config_host['LIBISCSI_LIBS'].split())
>  
>  subdir('contrib/libvhost-user')
> +subdir('contrib/rdmacm-mux')
>  subdir('contrib/vhost-user-blk')
>  subdir('contrib/vhost-user-scsi')