Re: [Qemu-devel] [PATCH] Makefile: fix up parallel building under MSYS+MinGW

[Paolo Bonzini <pbonzini@redhat.com>]

On 18/02/2015 13:59, Vasily Efimov wrote:
> This patch enables parallel building of QEMU in MSYS+MinGW environment.
> Currently an attempt to build QEMU in parallel fails on generation of
> version.lo (and version.o too).
> 
> The cause of the failure is that when listing prerequisites "Makefile"
> references "config-host.h" by absolute path in some rules and by relative
> path in others. Make cannot figure out that these references points to the
> same file which leads to the race: the generation of "version.*" which
> requires "$(BUILD_DIR)/config-host.h" is launched in parallel with the
> generation of "config-host.h" needed by other "Makefile" targets.
> 
> This patch removes "$(BUILD_DIR)/" prefix from corresponding prerequisite
> of "version.*". There is no other prerequisites "$(BUILD_DIR)/config-host.h"
> found.
> 
> Also note that not every version of MSYS is able to build QEMU in parallel,
> see: "http://sourceforge.net/p/mingw/bugs/1950/". The suggested version is
> 1.0.17.
> 
> Signed-off-by: Vasily Efimov <real@ispras.ru>
> ---
>  Makefile | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 6817c6f..b0d8c07 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -197,9 +197,9 @@ ALL_SUBDIRS=$(TARGET_DIRS) $(patsubst %,pc-bios/%, $(ROMS))
>  
>  recurse-all: $(SUBDIR_RULES) $(ROMSUBDIR_RULES)
>  
> -$(BUILD_DIR)/version.o: $(SRC_PATH)/version.rc $(BUILD_DIR)/config-host.h | $(BUILD_DIR)/version.lo
> +$(BUILD_DIR)/version.o: $(SRC_PATH)/version.rc config-host.h | $(BUILD_DIR)/version.lo
>  	$(call quiet-command,$(WINDRES) -I$(BUILD_DIR) -o $@ $<,"  RC    version.o")
> -$(BUILD_DIR)/version.lo: $(SRC_PATH)/version.rc $(BUILD_DIR)/config-host.h
> +$(BUILD_DIR)/version.lo: $(SRC_PATH)/version.rc config-host.h
>  	$(call quiet-command,$(WINDRES) -I$(BUILD_DIR) -o $@ $<,"  RC    version.lo")
>  
>  Makefile: $(version-obj-y) $(version-lobj-y)
> 

Applied, thanks.

Paolo