39d22b9678
Certain invalid operations trigger hardware error conditions. Error conditions that only halt one channel can be detected and recovered by resetting the channel. Error conditions that halt the whole device are generally not recoverable. Add a sysctl to inject channel-fatal HW errors, 'dev.ioat.<N>.force_hw_error=1'. When a halt due to a channel error is detected, ioat(4) blocks new operations from being queued on the channel, completes any outstanding operations with an error status, and resets the channel before allowing new operations to be queued again. Update ioat.4 to document error recovery; document blockfill introduced in r290021 while we are here; document ioat_put_dmaengine() added in r289907; document DMA_NO_WAIT added in r289982. Sponsored by: EMC / Isilon Storage Division
217 lines
6.2 KiB
Groff
217 lines
6.2 KiB
Groff
.\" Copyright (c) 2015 EMC / Isilon Storage Division
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd October 31, 2015
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.Dt IOAT 4
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.Os
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.Sh NAME
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.Nm I/OAT
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.Nd Intel I/O Acceleration Technology
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.Sh SYNOPSIS
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To compile this driver into your kernel,
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place the following line in your kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device ioat"
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.Ed
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.Pp
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Or, to load the driver as a module at boot, place the following line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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ioat_load="YES"
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.Ed
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.Pp
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In
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.Xr loader.conf 5 :
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.Pp
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.Cd hw.ioat.force_legacy_interrupts=0
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.Pp
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In
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.Xr loader.conf 5 or
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.Xr sysctl.conf 5 :
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.Pp
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.Cd hw.ioat.enable_ioat_test=0
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.Cd hw.ioat.debug_level=0
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(only critical errors; maximum of 3)
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.Pp
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.Ft typedef void
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.Fn (*bus_dmaengine_callback_t) "void *arg" "int error"
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.Pp
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.Ft bus_dmaengine_t
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.Fn ioat_get_dmaengine "uint32_t channel_index"
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.Ft void
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.Fn ioat_put_dmaengine "bus_dmaengine_t dmaengine"
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.Ft void
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.Fn ioat_acquire "bus_dmaengine_t dmaengine"
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.Ft void
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.Fn ioat_release "bus_dmaengine_t dmaengine"
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.Ft struct bus_dmadesc *
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.Fo ioat_copy
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.Fa "bus_dmaengine_t dmaengine"
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.Fa "bus_addr_t dst"
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.Fa "bus_addr_t src"
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.Fa "bus_size_t len"
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.Fa "bus_dmaengine_callback_t callback_fn"
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.Fa "void *callback_arg"
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.Fa "uint32_t flags"
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.Fc
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.Ft struct bus_dmadesc *
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.Fo ioat_blockfill
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.Fa "bus_dmaengine_t dmaengine"
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.Fa "bus_addr_t dst"
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.Fa "uint64_t fillpattern"
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.Fa "bus_size_t len"
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.Fa "bus_dmaengine_callback_t callback_fn"
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.Fa "void *callback_arg"
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.Fa "uint32_t flags"
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.Fc
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.Ft struct bus_dmadesc *
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.Fo ioat_null
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.Fa "bus_dmaengine_t dmaengine"
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.Fa "bus_dmaengine_callback_t callback_fn"
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.Fa "void *callback_arg"
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.Fa "uint32_t flags"
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.Fc
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.Sh DESCRIPTION
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The
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.Nm
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driver provides a kernel API to a variety of DMA engines on some Intel server
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platforms.
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.Pp
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There is a number of DMA channels per CPU package.
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(Typically 4 or 8.)
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Each may be used independently.
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Operations on a single channel proceed sequentially.
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.Pp
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Blockfill operations can be used to write a 64-bit pattern to memory.
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.Pp
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Copy operations can be used to offload memory copies to the DMA engines.
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.Pp
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Null operations do nothing, but may be used to test the interrupt and callback
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mechanism.
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.Pp
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All operations can optionally trigger an interrupt at completion with the
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.Ar DMA_EN_INT
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flag.
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For example, a user might submit multiple operations to the same channel and
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only enable an interrupt and callback for the last operation.
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.Pp
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All operations are safe to use in a non-blocking context with the
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.Ar DMA_NO_WAIT
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flag.
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(Of course, allocations may fail and operations requested with
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.Ar DMA_NO_WAIT
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may return NULL.)
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.Pp
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All operations, as well as
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.Fn ioat_get_dmaengine ,
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can return NULL in special circumstances.
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For example, if the
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.Nm
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driver is being unloaded, or the administrator has induced a hardware reset, or
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a usage error has resulted in a hardware error state that needs to be recovered
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from.
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.Pp
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It is invalid to attempt to submit new DMA operations in a
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.Fa bus_dmaengine_callback_t
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context.
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.Sh USAGE
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A typical user will lookup the DMA engine object for a given channel with
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.Fn ioat_get_dmaengine .
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When the user wants to offload a copy, they will first
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.Fn ioat_acquire
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the
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.Ar bus_dmaengine_t
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object for exclusive access to enqueue operations on that channel.
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Then, they will submit one or more operations using
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.Fn ioat_blockfill ,
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.Fn ioat_copy ,
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or
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.Fn ioat_null .
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After queueing one or more individual DMA operations, they will
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.Fn ioat_release
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the
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.Ar bus_dmaengine_t
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to drop their exclusive access to the channel.
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The routine they provided for the
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.Fa callback_fn
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argument will be invoked with the provided
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.Fa callback_arg
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when the operation is complete.
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When they are finished with the
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.Ar bus_dmaengine_t ,
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the user should
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.Fn ioat_put_dmaengine .
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.Pp
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Users MUST NOT block between
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.Fn ioat_acquire
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and
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.Fn ioat_release .
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Users SHOULD NOT hold
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.Ar bus_dmaengine_t
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references for a very long time to enable fault recovery and kernel module
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unload.
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.Pp
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For an example of usage, see
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.Pa src/sys/dev/ioat/ioat_test.c .
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.Sh FILES
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.Bl -tag -compat
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.It Pa /dev/ioat_test
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test device for
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.Xr ioatcontrol 8
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.El
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.Sh SEE ALSO
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.Xr ioatcontrol 8
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Fx 11.0 .
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.Sh AUTHORS
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The
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.Nm
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driver was developed by
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.An \&Jim Harris Aq Mt jimharris@FreeBSD.org ,
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.An \&Carl Delsey Aq Mt carl.r.delsey@intel.com ,
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and
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.An \&Conrad Meyer Aq Mt cem@FreeBSD.org .
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This manual page was written by
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.An \&Conrad Meyer Aq Mt cem@FreeBSD.org .
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.Sh CAVEATS
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Copy operation takes bus addresses as parameters, not virtual addresses.
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.Pp
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Buffers for individual copy operations must be physically contiguous.
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.Pp
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Copies larger than max transfer size (1MB, but may vary by hardware) are not
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supported.
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Future versions will likely support this by breaking up the transfer into
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smaller sizes.
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.Sh BUGS
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The
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.Nm
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driver only supports blockfill, copy, and null operations at this time.
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The driver does not yet support advanced DMA modes, such as XOR, that some
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I/OAT devices support.
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