1.\" $OpenBSD: dma_alloc.9,v 1.6 2013/06/04 19:27:05 schwarze Exp $ 2.\" $NetBSD: pool.9,v 1.18 2001/06/21 11:59:01 wiz Exp $ 3.\" 4.\" Copyright (c) 2011 Theo de Raadt 5.\" All rights reserved. 6.\" 7.\" Permission to use, copy, modify, and distribute this software for any 8.\" purpose with or without fee is hereby granted, provided that the above 9.\" copyright notice and this permission notice appear in all copies. 10.\" 11.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 12.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 14.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 17.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18.\" 19.Dd $Mdocdate: June 4 2013 $ 20.Dt DMA_ALLOC 9 21.Os 22.Sh NAME 23.Nm dma_alloc , 24.Nm dma_free 25.Nd DMA-safe memory allocator 26.Sh SYNOPSIS 27.In sys/types.h 28.In sys/pool.h 29.Ft void * 30.Fo dma_alloc 31.Fa "size_t size" 32.Fa "int flags" 33.Fc 34.Ft void 35.Fo dma_free 36.Fa "void *m" 37.Fa "size_t size" 38.Fc 39.Sh DESCRIPTION 40This allocator provides DMA-safe memory managed using the 41.Xr pool 9 42interface. 43It is safe to call in most contexts and is 44typically used for temporary buffers up to 65536 bytes. 45When buffers are used many times it may be better to consider 46using other DMA-safe allocators. 47.Pp 48Interrupt protection is set to 49.Va IPL_VM 50using 51.Xr pool_setipl 9 . 52.Pp 53The 54.Ar flags 55argument is a selection of 56.Xr pool_get 9 57flag arguments. 58.Pp 59The same 60.Va size 61argument must be passed to both 62.Fn dma_alloc 63and the subsequent 64.Fn dma_free . 65Allocations over 65536 will fail. 66.Sh SEE ALSO 67.Xr bus_dma 9 , 68.Xr mbuf 9 , 69.Xr pool 9 70.Sh HISTORY 71The 72.Nm 73interface first appeared in 74.Ox 4.8 . 75