Re: [Qemu-devel] one question on the makefile

[Richard Yang]

On Tue, Jun 12, 2012 at 10:50:33AM +0200, Paolo Bonzini wrote:
>Il 12/06/2012 10:33, Wei Yang ha scritto:
>> .PHONY: $(patsubst %, check-qtest-%, $(QTEST_TARGETS))
>> $(patsubst %, check-qtest-%, $(QTEST_TARGETS)): check-qtest-%: 
>> $(check-qtest-y)
>>      $(call quiet-command,QTEST_QEMU_BINARY=$*-softmmu/qemu-system-$* \
>>              gtester $(GTESTER_OPTIONS) -m=$(SPEED) 
>> $(check-qtest-$*-y),"GTESTER $@")
>> 
>> I know the general idea is to create a rule for target such as
>> check-qtest-x86_64.
>> 
>> There are two colons, usually there is one colon in dependency.
>
>Search for "Static pattern rules".  Static pattern rules are probably
>the single most useful GNU make extension.  They greatly limit the
>amount of "magic" the make does, so the resulting Makefiles are more
>easily debuggable.  Here is an extract from the GNU make manual:
>
>=====
>     TARGETS ...: TARGET-PATTERN: PREREQ-PATTERNS ...
>             RECIPE
>             ...
>
>The TARGETS list specifies the targets that the rule applies to.  The
>targets can contain wildcard characters, just like the targets of
>ordinary rules (*note Using Wildcard Characters in File Names:
>Wildcards.).
>
>   The TARGET-PATTERN and PREREQ-PATTERNS say how to compute the
>prerequisites of each target.  Each target is matched against the
>TARGET-PATTERN to extract a part of the target name, called the "stem".
>This stem is substituted into each of the PREREQ-PATTERNS to make the
>prerequisite names (one from each PREREQ-PATTERN).
>=====
>
>
>$* is also replaced by the stem.  In fact in this case, the stem is not
>used in the PREREQ-PATTERNS, it is only used in the commands.
>
>Paolo
Thanks :)
I learn it. 

-- 
Richard Yang
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