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

[Sam Ravnborg]

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
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