Messages in this thread | | | Date | Fri, 11 Jul 2008 12:28:44 +0200 | From | Sam Ravnborg <> | Subject | Re: [PATCH 0/5] x86/pci: patches for tip/x86/unify-pci |
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> > > > obj-y is empty when you enter the Makefile. > > So if you start out with ':=' or '+=' is no difference. > > i guess it's safer to use +=, because it's ordering invariant. > > We should use := only if we absolutely want to override the current > rules.
In the past I was carefully to use ':=' for the first assignmnet so the variable was a " simply expanded variables" variable. But as I have added a 'obj-y := ' in kbuild we should be safe.
" simply expanded variables" is some special make stuff.
A typical:
FOO = bar
is a "recursively expanded variable". Here the assingment is evaluated on each usage.
Sam
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