Robert P. J. Day wrote: > i'm perusing the generic-2.6.24 linux patches in the svn checkout, > and i'm curious about patch 004-extra_optimization.patch: > > ===== > --- linux-2.6.23-rc6.orig/Makefile 2007-09-21 16:23:55.000000000 +0800 > +++ linux-2.6.23-rc6/Makefile 2007-09-21 16:23:56.000000000 +0800 > @@ -508,6 +508,9 @@ > NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) > CHECKFLAGS += $(NOSTDINC_FLAGS) > > +# improve gcc optimization > +CFLAGS += $(call cc-option,-funit-at-a-time,) > + > # warn about C99 declaration after statement > CFLAGS += $(call cc-option,-Wdeclaration-after-statement,) > ===== > > i'm used to openwrt patches that fix actual issues, but the above is > apparently only for an optimization. is it necessary for openwrt? is > there a reason that it isn't in the kernel Makefile itself? > > i guess i'm just curious about patches that appear optional in some > sense. thanks. It is not strictly necessary, but it allows gcc to expand the scope of inlining analysis to generate better code. I don't know if that's something for upstream inclusion.
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