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PR/56947 CVS commit: src/sys/dev/audio

The following reply was made to PR kern/56947; it has been noted by GNATS.

From: "Tetsuya Isaki" <>
Subject: PR/56947 CVS commit: src/sys/dev/audio
Date: Sat, 13 Aug 2022 06:47:41 +0000

 Module Name:	src
 Committed By:	isaki
 Date:		Sat Aug 13 06:47:41 UTC 2022
 Modified Files:
 	src/sys/dev/audio: audio.c audiodef.h
 Log Message:
 audio: Rework about usrbuf allocation.
 - Allocate the usrbuf from kmem(9) instead of uvm(9).  The usrbuf has used
   uvm(9), in case mmap(2) might be issued later.  However, despite the most
   apps don't use mmap(2), allocating (and reallocating) uvm(9) every time
   would be expensive.  In addition, uvm(9) for recording usrbuf was totally
   pointless now.
 - For playback, the usrbuf memory will be allocated in pages.  Because the
   usrbuf for playback is mostly near 64KB for backward compatibility.
   This will reduce reallocation especially from the initial ulaw to the most
   commonly used format like slinear16/2ch/48kHz.
 - When mmap(2) is called, it will replace the playback usrbuf from kmem(9) to
 - Prohibit changing playback format once mmap(2) is called.
   It follows netbsd-7.
 - For recording, the usrbuf memory will be allocated in the requested size
   every time as before.  Because the usrbuf for recording is only one block
   and is enough small to the page in the most case.
 Inspired by PR kern/56947.
 To generate a diff of this commit:
 cvs rdiff -u -r1.134 -r1.135 src/sys/dev/audio/audio.c
 cvs rdiff -u -r1.19 -r1.20 src/sys/dev/audio/audiodef.h
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

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