Re: [PATCH] Makefile: Keep trace-events-subdirs ordered

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 1/16/20 10:13 AM, Philippe Mathieu-Daudé wrote:
> To ease review and reduce likelihood of merge failures (see [*]),
> keep trace-events-subdirs ordered when possible, following eb7ccb3c0.
> 
> [*] https://www.mail-archive.com/qemu-devel@nongnu.org/msg671007.html
>      Duplicate trace-events-subdirs entries generates duplicated
>      symbols when using the LTTng Userspace Tracer library.

If it seems useful/relevant we can add to this description UST backend 
config and the error when using duplicate entries:

   $ ./configure --enable-trace-backends=ust && make
   [...]
     CC      trace-ust-all.o
   In file included from trace-ust-all.h:13,
                    from trace-ust-all.c:13:
   trace-ust-all.h:35151:1: error: redefinition of 
‘__tracepoint_cb_qemu___loader_write_rom’
   35151 | TRACEPOINT_EVENT(
         | ^~~~~~~~~~~~~~~~
   trace-ust-all.h:31791:1: note: previous definition of 
‘__tracepoint_cb_qemu___loader_write_rom’ was here
   31791 | TRACEPOINT_EVENT(
         | ^~~~~~~~~~~~~~~~

> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> "Fixes: 26b8e6dc & 8d5d515a0"
> 
> To be even safer we should use $(sort $(trace-events-subdirs))
> ---
>   Makefile.objs | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/Makefile.objs b/Makefile.objs
> index 7c1e50f9d6..d62f908965 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -142,8 +142,8 @@ trace-events-subdirs += nbd
>   trace-events-subdirs += scsi
>   endif
>   ifeq ($(CONFIG_SOFTMMU),y)
> -trace-events-subdirs += chardev
>   trace-events-subdirs += audio
> +trace-events-subdirs += chardev
>   trace-events-subdirs += hw/9pfs
>   trace-events-subdirs += hw/acpi
>   trace-events-subdirs += hw/alpha
> @@ -191,6 +191,7 @@ trace-events-subdirs += migration
>   trace-events-subdirs += net
>   trace-events-subdirs += ui
>   endif
> +trace-events-subdirs += hw/core
>   trace-events-subdirs += hw/display
>   trace-events-subdirs += qapi
>   trace-events-subdirs += qom
> @@ -203,7 +204,6 @@ trace-events-subdirs += target/riscv
>   trace-events-subdirs += target/s390x
>   trace-events-subdirs += target/sparc
>   trace-events-subdirs += util
> -trace-events-subdirs += hw/core
>   
>   trace-events-files = $(SRC_PATH)/trace-events $(trace-events-subdirs:%=$(SRC_PATH)/%/trace-events)
>   
>