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Re: [Qemu-devel] [RFC PATCH v3 3/5] Makefile: introduce common-obj-m and
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [RFC PATCH v3 3/5] Makefile: introduce common-obj-m and block-obj-m for DSO |
Date: |
Tue, 10 Sep 2013 12:01:13 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130805 Thunderbird/17.0.8 |
Il 10/09/2013 11:42, Fam Zheng ha scritto:
> On Tue, 09/10 08:45, Paolo Bonzini wrote:
>> Il 10/09/2013 03:02, Fam Zheng ha scritto:
>>> -all: $(DOCS) $(TOOLS) $(HELPERS-y) recurse-all
>>> +# static linked mods are expanded to .o list
>>> +dummy := $(call expand-mod-obj,common-obj-y)
>>> +dummy := $(call expand-mod-obj,block-obj-y)
>>> +
>>> +modules-m = $(patsubst %.o,%$(DSOSUF),$(filter %.o,$(block-obj-m)
>>> $(common-obj-m))) \
>>> + $(patsubst %.mo,%$(DSOSUF),$(filter %.mo,$(block-obj-m)
>>> $(common-obj-m)))
>>> +
>>> +all: $(DOCS) $(TOOLS) $(HELPERS-y) recurse-all $(modules-m)
>>> +
>>> +# Generate rules for single file modules (%.so: %.o).
>>> +$(foreach o,$(filter %.o,$(block-obj-m) $(common-obj-m)),$(eval \
>>> + $(patsubst %.o,%.so,$o): $o))
>>> +
>>> +# For multi file modules, dependencies should be listed explicitly in
>>> +# Makefile.objs as
>>> +# foo.mo-objs := bar.o biz.o
>>> +$(foreach o,$(filter %.mo,$(block-obj-m) $(common-obj-m)),$(eval \
>>> + $(patsubst %.mo,%.so,$o): $($o-objs)))
>>
>> I agree that this foo.mo-objs variable is homogeneous with how you
>> handle libraries and cflags. I like it now.
>>
>> However, I don't like the many places in which you have to special-case
>> modules (expand-mod-obj, modules-m, etc.), and the duplication between
>> Makefile and Makefile.target.
>>
>> I would prefer if you try doing this patch along the lines I suggested
>> in my review of v2, using .mo files as a placeholder and then doing the
>> final link either into the .so or in the executable. This should remove
>> the need for at least expand-mod-obj, and probably for more of the
>> duplicated constructs you have.
>>
> OK. I'll try.
>
>> In particular, I would like modules-m to be simply "$(block-obj-m)
>> $(common-obj-m)".
>
> There need to be some variable with %.o and %.mo subst to %.so, to become
> dependency of target "all".
I think you are putting too much weight on %.so, which complicates
things when handling both modular and non-modular builds. Assuming you
have transformed block-obj-m and common-obj-m to only contain .mo files,
with something like this:
define add-modules
$(foreach o, $(filter-out %.o, $($1)), $(eval $o-objs := $o))
$(eval modules-m += $(patsubst %.o,%.mo,$($1)))
endif
dummy := $(call add-modules,block-obj-m)
dummy := $(call add-modules,common-obj-m)
then building modules can be just a bunch of extra targets:
ifeq ($(CONFIG_MODULES),y)
modules: $(patsubst %.mo,%$(DSOSUF),$(modules-m))
all: modules
endif
>> In the medium term, we need to find a way to avoid the duplication:
>>
>> block-obj-y = block/
>> block-obj-m = block/
>>
>> Perhaps by introducing a "dirs" variable that automatically triggers
>> recursion on all nested variables. But this can be the topic of a
>> separate patch series, if you prefer.
>>
> Agree but prefer to do it in a separate series.
Sure.
Paolo
[Qemu-devel] [RFC PATCH v3 4/5] module: implement module loading function, Fam Zheng, 2013/09/09
[Qemu-devel] [RFC PATCH v3 5/5] block: build qed and curl as shared library, Fam Zheng, 2013/09/09