On Thu, Feb 20, 2003 at 11:03:38PM +0100, Brian Murphy wrote: > Jun Sun wrote: > > >Is this allowed? Can't find any such usage in kernel other > >than the worrisome comment below: > > > >arch/arm/Makefile:# Grr, ?= doesn't work as all the other assignment operators do. Make bug? > > > > > > > > > The arm code does this: > > # Only set INCDIR if its not already defined above > # Grr, ?= doesn't work as all the other assignment operators do. Make bug? > ifeq ($(origin INCDIR), undefined) > INCDIR := $(MACHINE) > endif > > where the make docs say: > > INCDIR ?= $(MACHINE) > > is the same as > > ifeq ($(origin INCDIR), undefined) > INCDIR = $(MACHINE) > endif > > which means INCDIR will reflect changes to MACHINE. > The := form sets INCDIR once and for all. What do you want? ':=' is fine, as long as "?=" is deemed appropriate for kernel and hackers. Jun
