lib/44660: sysconf(3) plays badly with modules autoloading

[njoly%pasteur.fr@localhost]

>Number:         44660
>Category:       lib
>Synopsis:       sysconf(3) plays badly with modules autoloading
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Mar 01 19:55:00 +0000 2011
>Originator:     Nicolas Joly
>Release:        NetBSD 5.99.47
>Organization:
Insitut Pasteur
>Environment:
System: NetBSD lanfeust.sis.pasteur.fr 5.99.47 NetBSD 5.99.47 (LANFEUST) #13: 
Tue Mar 1 11:53:45 CET 2011 
njoly%lanfeust.sis.pasteur.fr@localhost:/local/src/NetBSD/obj.amd64/sys/arch/amd64/compile/LANFEUST
 amd64
Architecture: x86_64
Machine: amd64
>Description:
sysconf(3) does not work when some kernel subsystems are available with
modules autoloading system. By example, aio and mqueue ... now
the default on both i386 and amd64 GENERIC kernels.

sysconf(_SC_AIO_MAX) do query the `kern.aio_max' sysctl node, which do not
exists until the module is loaded.

njoly@lanfeust [~]> getconf -a >/dev/null
getconf: sysconf(51): No such file or directory
njoly@lanfeust [~]> getconf AIO_LISTIO_MAX
getconf: sysconf(51): No such file or directory
njoly@lanfeust [~]> getconf AIO_MAX
getconf: sysconf(52): No such file or directory

>How-To-Repeat:
>Fix: