75 lines
1.9 KiB
Groff
75 lines
1.9 KiB
Groff
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.\" $OpenBSD: dma_alloc.9,v 1.8 2022/03/31 17:27:23 naddy Exp $
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.\" $NetBSD: pool.9,v 1.18 2001/06/21 11:59:01 wiz Exp $
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.\"
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.\" Copyright (c) 2011 Theo de Raadt
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.\" All rights reserved.
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.Dd $Mdocdate: March 31 2022 $
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.Dt DMA_ALLOC 9
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.Os
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.Sh NAME
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.Nm dma_alloc ,
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.Nm dma_free
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.Nd DMA-safe memory allocator
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.Sh SYNOPSIS
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.In sys/types.h
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.In sys/pool.h
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.Ft void *
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.Fo dma_alloc
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.Fa "size_t size"
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.Fa "int flags"
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.Fc
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.Ft void
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.Fo dma_free
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.Fa "void *m"
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.Fa "size_t size"
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.Fc
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.Sh DESCRIPTION
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This allocator provides DMA-safe memory managed using the
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.Xr pool 9
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interface.
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It is safe to call in most contexts and is
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typically used for temporary buffers up to 65536 bytes.
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When buffers are used many times, it may be better to consider
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using other DMA-safe allocators.
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.Pp
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Interrupt protection is set to
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.Va IPL_VM
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using
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.Xr pool_init 9 .
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.Pp
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The
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.Ar flags
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argument is a selection of
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.Xr pool_get 9
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flag arguments.
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.Pp
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The same
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.Va size
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argument must be passed to both
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.Fn dma_alloc
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and the subsequent
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.Fn dma_free .
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Allocations over 65536 will fail.
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.Sh SEE ALSO
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.Xr bus_dma 9 ,
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.Xr mbuf 9 ,
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.Xr pool 9
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.Sh HISTORY
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The
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.Nm
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interface first appeared in
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.Ox 4.8 .
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