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Date: Wed, 06 May 2015 16:07:14 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] rules.mak: Force CFLAGS for all objects in
	DSO
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To: Fam Zheng <famz@redhat.com>, qemu-devel@nongnu.org
Cc: Peter Maydell <peter.maydell@linaro.org>, Michael Tokarev <mjt@tls.msk.ru>, agraf@suse.de, Stefan Weil <sw@weilnetz.de>



On 06/05/2015 15:46, Fam Zheng wrote:
> Because of the trick of process-archive-undefs, all .mo objects, even
> with --enable-modules, are dependencies of executables.
> 
> This breaks CFLAGS propogation because the compiling of module object
> will happen too early before building for DSO.
> 
> With GCC 5, the linking would fail because .o doesn't have -fPIC. Also,
> BUILD_DSO will be missed. (module-common.o will have it, so the stamp
> symbol was still liked in .so).
> 
> Fix the problem by forcing the CFLAGS during unnest-vars.
> 
> Reported-by: Alexander Graf <agraf@suse.de>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  rules.mak | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/rules.mak b/rules.mak
> index 3a05627..6c0caf3 100644
> --- a/rules.mak
> +++ b/rules.mak
> @@ -102,7 +102,6 @@ endif
>  %.o: %.dtrace
>  	$(call quiet-command,dtrace -o $@ -G -s $<, "  GEN   $(TARGET_DIR)$@")
>  
> -%$(DSOSUF): CFLAGS += -fPIC -DBUILD_DSO
>  %$(DSOSUF): LDFLAGS += $(LDFLAGS_SHARED)
>  %$(DSOSUF): %.mo
>  	$(call LINK,$^)
> @@ -353,6 +352,7 @@ define unnest-vars
>               $(foreach o,$($v),
>                     $(eval $o: $($o-objs)))
>               $(eval $(patsubst %-m,%-y,$v) += $($v))
> +             $(eval $($v:%.mo=%$(DSOSUF)) $($v) $(foreach o,$($v),$($o-objs)) .PHONY: CFLAGS += -fPIC -DBUILD_DSO)

Can you explain the various parts to the left of the colon?

Thanks,

Paolo

>               $(eval modules: $($v:%.mo=%$(DSOSUF))),
>               $(eval $(patsubst %-m,%-y,$v) += $(call expand-objs, $($v)))))
>  
>