Building alsa drivers as part of alsa vs kernel external module

Building alsa drivers as part of alsa vs kernel external module

[Ben Stanley]

Hi,

I'm trying to compile the AudioScience driver as an external kernel
module (i.e. using the alsa in the kernel, rather than as a module
within the alsa tree).

What source code transformations can I expect to have to make?

Is there some documentation anywhere on what transformations are
performed as standard?

Or is there a proper way that the module should be written so that it
compiles both ways?

Of course, I understand that patches will most likely be required for
the module to compile against older kernels in particular. This kind of
problem is usually dealt with by autoconf. Is there a standard way of
doing this for just compiling a module directly for the kernel? I see
that alsa has its own set of autoconf macros, and when I compile
directly for the kernel (and its embedded alsa) I will lose the benefit
of that.

Ben Stanley.

Re: Building alsa drivers as part of alsa vs kernel external module

[Takashi Iwai]

At Mon, 26 May 2008 14:48:12 +1000,
Ben Stanley wrote:
> 
> Hi,
> 
> I'm trying to compile the AudioScience driver as an external kernel
> module (i.e. using the alsa in the kernel, rather than as a module
> within the alsa tree).
> 
> What source code transformations can I expect to have to make?

Copy alsa-driver/pci/asihpi/*, modify Kconfig and Makefile.
Remove inclusion of adriver.h, and eventually fix the build error.

> Is there some documentation anywhere on what transformations are
> performed as standard?

There is no standard for doing this.  The only standard is to build
the modules in alsa-driver tree.

> Or is there a proper way that the module should be written so that it
> compiles both ways?
> 
> Of course, I understand that patches will most likely be required for
> the module to compile against older kernels in particular. This kind of
> problem is usually dealt with by autoconf. Is there a standard way of
> doing this for just compiling a module directly for the kernel? I see
> that alsa has its own set of autoconf macros, and when I compile
> directly for the kernel (and its embedded alsa) I will lose the benefit
> of that.

Yes.  The compatible layer for older kernels is really messy, and you
just need do trial and error...


Takashi