[alsa-devel] Per option CFLAGS?

Adrian Bunk bunk at kernel.org
Sat Sep 15 10:47:55 CEST 2007

On Sat, Sep 15, 2007 at 01:30:21AM +0200, Rene Herman wrote:
> On 09/15/2007 01:13 AM, H. Peter Anvin wrote:
>> Rene Herman wrote:
>>> I have a single file foo.c that I want to generate two (ALSA) modules
>>> from, snd-foo2000.ko and snd-foo2001.ko, by compiling with either
>>> FOO2000 or FOO2001 defined.
>>> I can do this, and ALSA does this a few times, by providing dummy
>>> foo2000.c and foo2001.c files, like:
>>> === foo2000.c
>>> #define FOO2000
>>> #include "foo.c"
>>> ===
>>> and a regular Makefile
>>> ===
>>> foo2000-objs := foo2000.o
>>> foo2001-objs := foo2001.o
>>> obj-$(CONFIG_SND_FOO2000) += snd-foo2000.o
>>> obj-$(CONFIG_SND_F002001) += snd-foo2001.o
>>> ===
>>> That #include is a little lame though. Is there a nicer way? I noticed
>>> the per-file CFLAGS, but given that it's one source file for both, that
>>> doesn't fit.
>> The stub source file is usually considered a good way to do this.
> Mmm. If I'll have to live with it, I can, but thought I'd ask if there was 
> some nice build trickery available instead.

The usual trick is to create _three_ modules:

Two with the foo2000 and foo2001 specific parts, and a third one with 
all code used by both.

Or if foo2000 and foo2001 differ only in small details, create one 
snd-foo200x module supporting both at the same time.

> Rene.



       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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