Re: [HOWTO] set extra_cflags to indicate compilation against -mmkernels

[Michael Krufky]

Sam Ravnborg wrote:

> On Sat, Jul 30, 2005 at 05:29:21PM -0400, Michael Krufky wrote:
>  
>
> > With the addition of topdir-mm.patch into the -mm tree (since 
> > 2.6.13-rc3-mm2), it is now possible for Makefile to detect whether a cvs 
> > subtree is being built against -mm or not...  -mm kernels now have a .mm 
> > file in the top level directory.
> >
> > inside Makefile:
> >
> > mm-kernel := $(TOPDIR)/.mm
> > ifneq ($(mm-kernel),)
> > MM_KERNEL_CFLAGS	:= -DMM_KERNEL=$(shell cat $(mm-kernel) 2> /dev/null)
> > ifneq ($(MM_KERNEL_CFLAGS),-DMM_KERNEL=)
> > EXTRA_CFLAGS		+= $(MM_KERNEL_CFLAGS)
> > endif
> > endif
> >    
>
> Hi Michael.
> The content of the .mm file seems to be insignificant - '1'. The important
> issue is that the file is present.
> Also please do not use $(TOPDIR) - it is deprecated.
>
> The following is enough:
> EXTRA_CFLAGS += $(if $(wildcard $(srctree)/.mm), -DMM_KERNEL)
>
> If the file exist in the root of the kernel src tree MM_KERNEL will be
> added to EXTRA_CFLAGS.
Sam-

Thank you!  I knew there might be a more efficient way to do that, so 
I'm glad I sent that to LKML for you to see ;-)

Still, I think it should be added into the documentation somewhere... 
I'd be happy to submit a patch, I just don't know where it should go.  
Obviously, this is specific to -mm kernels only.  Do you know?

--
Michael Krufky

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