docs/79156: buffersize knob for sound(4) is a tunable, not a sysctl.

[trasz at buziaczek.pl]

>Number:         79156
>Category:       docs
>Synopsis:       buffersize knob for sound(4) is a tunable, not a sysctl.
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-doc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          doc-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Mar 23 09:20:01 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     trasz
>Release:        FreeBSD 5.3-RELEASE-p5 i386
>Organization:
>Environment:
System: FreeBSD pin.if.uz.zgora.pl 5.3-RELEASE-p5 FreeBSD 5.3-RELEASE-p5 #0: Sun Jan 16 12:27:41 CET 2005 trasz at pin.if.uz.zgora.pl:/usr/obj/usr/src/sys/PIN i386


>Description:
        sound(4) man page claims that 'hw.snd.pcm%d.buffersize' can be configured
        via sysctl.  that's not true, however: in /sys/dev/sound/pcm/sound.c
        there is:

        SYSCTL_ADD_INT(snd_sysctl_tree(dev), SYSCTL_CHILDREN(snd_sysctl_tree_top(dev)),
            OID_AUTO, "buffersize", CTLFLAG_RD, &d->bufsz, 0, "");
 
        so the sysctl is read-only.  buffersize can be set via tunable
        'hint.pcm.0.buffersize', either in loader.conf or device.hints.

>How-To-Repeat:
	type 'man sound' and scroll two pages down.

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: