[alsa-devel] usr/include/linux/soundcard.h warnings for 'make headers_check'

[Takashi Iwai]

At Wed, 04 Feb 2009 16:07:57 +0530,
Jaswinder Singh Rajput wrote:
> 
> On Wed, 2009-02-04 at 10:03 +0100, Takashi Iwai wrote:
> > At Wed, 04 Feb 2009 14:04:54 +0530,
> > Jaswinder Singh Rajput wrote:
> > > 
> > > On Wed, 2009-02-04 at 07:39 +0100, Takashi Iwai wrote:
> > > > At Wed, 04 Feb 2009 09:34:12 +0530,
> > > > Jaswinder Singh Rajput wrote:
> > > > > 
> > > > > On Tue, 2009-02-03 at 21:27 +0100, Arnd Bergmann wrote:
> > > > > > On Wednesday 21 January 2009, Sam Ravnborg wrote:
> > > > > > > 
> > > > > > > > No, these are declarations for OSS-lib.
> > > > > > > > It doesn't belong to kernel, but it's better to keep it for
> > > > > > > > compatibility in some way.
> > > > > > > 
> > > > > > > But not in the kernel for sure.
> > > > > > > I just checked and for example: OSS_init is not used anywhere in the kernel.
> > > > > > > The kernel headers are not a "dump all your stuff" ground anymore.
> > > > > > > 
> > > > > > > So I encourage you to find a better home for the user space library definitons.
> > > > > > > We can let the definiton stay for a while - but eventually they have to
> > > > > > > be dropped from the kernel.
> > > > > > 
> > > > > > The last free version of OSSlib that matches this header is from ~1997, and
> > > > > > no current distro appears to be shipping it. All new OSSlib versions (the
> > > > > > oldest I found was from ~2003) contain in their documentation:
> > > > > > 
> > > > > > "Older versions of some OSS include files are distributed
> > > > > >  with various operating systems. There is no danger in
> > > > > >  using them but applications written for more recent OSS
> > > > > >  versions will not compile with older header files.
> > > > > > 
> > > > > >  The latest versions of these include files (such as
> > > > > >  soundcard.h) are distributed in ../include/sys. Use
> > > > > >  the -I/usr/lib/oss/include switch when compiling
> > > > > >  programs. Alternatively copy these files to /usr/include/sys
> > > > > >  so that they replace the original ones."
> > > > > > 
> > > > > > I think it's safe enough to assume that everyone that builds against
> > > > > > OSSlib by now also has the correct version of the header installed.
> > > > > > Consequently, we should just drop the #ifndef __KERNEL__ section
> > > > > > of soundcard.h (all the macros in there depend on the extern
> > > > > > declarations), and maybe add an
> > > > > > 
> > > > > > #ifdef OSSLIB
> > > > > > #error need to use <sys/soundcard.h> from libOSSlib
> > > > > > #endif
> > > > > > 
> > > > > 
> > > > > sys/soundcard.h is also pointing to linux/soundcard.h, we need to move
> > > > > all this stuff to sys/soundcard.h.
> > > > 
> > > > All which stuff?
> > > > If you are referring to OSS-lib stuff in soundcard.h, then I'm for
> > > > it.
> > > > 
> > > 
> > > We need to fix things in such a way that we can replace:
> > > #if (!defined(__KERNEL__) && !defined(KERNEL) && !defined(INKERNEL) && !defined(_KERNEL)) || defined(USE_SEQ_MACROS)
> > > with
> > > #ifdef __KERNEL__
> > > and only keep those things in this file which we need in kernel and move
> > > userspace declarations which are not required for kernel to
> > > sys/soundcard.h
> > 
> > Which means to remove only the OSS-lib part.  Some other macros are
> > used in sound/oss/*.c.  And, there are cases that apps want to use
> > SEQ* macros without oss-lib (which are actually most cases).
> > 
> 
> In kernel space we use USE_SEQ_MACROS in:
> sound/oss/mpu401.c
> sound/oss/midi_synth.c
> 
> so we can replace
> #if (!defined(__KERNEL__) && !defined(KERNEL) && !defined(INKERNEL) && !defined(_KERNEL)) || defined(USE_SEQ_MACROS)
> with
> #ifdef USE_SEQ_MACROS

Then this will break user-space apps.  They don't define
USE_SEQ_MACROS always.


Takashi

> and keep SEQ* macros used by above files so we do not break kernel and
> move rest of the block in sys/soundcard.h so userspace will be also
> happy.