[Openal-devel] alsa backend on newer distro without libasound.so

[Fabian Knittel]

Hi everyone,

Prakash Punnoor schrieb:
> Am Dienstag 19 Juni 2007 schrieb Michael Zeilfelder:
>> I'm a little at loss of how to fix a certain problem.
>>
>> In short the problem is that alc_backend_alsa.c does try to open (with
>> alDLOpen_)  libasound.so which is not available on some newer distributions
>> which only have libasound.so.2
>>
>> It could be fixed either by me by also checking for libasound.so.2 in
>> alc_backend_alsa.c or it could be fixed by my users by creating a link from
>> libasound.so.2 to libasound.so.
> 
> Sounds like a bug of the distri to me. Shouldn't there *always* be a link 
> to .so? Does linking to libasound work w/o the .so link?

AFAIK, .so is only used at build-time and is usually a symbolic link to
.so.X. The linker looks at the symbolic link and embeds .so.X as runtime
dependency within the compiled executable.

The executable thereafter depends on the library with major version X.
.so.X OTOH is just a link to .so.X.Y (Y being the library's minor
version number).

On systems without a build-environment there's no need for the .so
symbolic link, as the binaries directly depend on .so.X.

Libraries with compatible interfaces increase their minor version
numbers (Y), the .so.X -> .so.X.Y-link is updated and everything
continues to work fine.


In conclusion, assuming a typical distribution, searching for
libasound.so only works as long as the openal development packages are
installed (e.g. in Debian that would be the libopenal*-dev package),
containing the necessary symbolic link.

IMVHO, openal should search for all libasound.so.X where X represents a
major library version interface supported by openal. E.g. if openal
needs a symbol libasound.so.X doesn't provide, there's no way this can
be worked around without forcing the user to install an appropriate
library or updating openal.

Greetings, Fabian

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