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32 .Nd Intel I/O Acceleration Technology
38 .Cd hw.ioat.force_legacy_interrupts=0
44 .Cd hw.ioat.enable_ioat_test=0
45 .Cd hw.ioat.debug_level=0
46 (only critical errors; maximum of 3)
49 .Fn (*bus_dmaengine_callback_t) "void *arg"
52 .Fn ioat_get_dmaengine "uint32_t channel_index"
54 .Fn ioat_acquire "bus_dmaengine_t dmaengine"
56 .Fn ioat_release "bus_dmaengine_t dmaengine"
57 .Ft struct bus_dmadesc *
59 .Fa "bus_dmaengine_t dmaengine"
63 .Fa "bus_dmaengine_callback_t callback_fn"
64 .Fa "void *callback_arg"
67 .Ft struct bus_dmadesc *
69 .Fa "bus_dmaengine_t dmaengine"
70 .Fa "bus_dmaengine_callback_t callback_fn"
71 .Fa "void *callback_arg"
77 driver provides a kernel API to a variety of DMA engines on some Intel server
80 There is a number of DMA channels per CPU package.
82 Each may be used independently.
83 Operations on a single channel proceed sequentially.
85 Copy operations may be used to offload memory copies to the DMA engines.
87 Null operations do nothing, but may be used to test the interrupt and callback
90 All operations can optionally trigger an interrupt at completion with the
93 For example, a user might submit multiple operations to the same channel and
94 only enable an interrupt and callback for the last operation.
96 A typical user will lookup the DMA engine object for a given channel with
97 .Fn ioat_get_dmaengine .
98 When the user wants to offload a copy, they will first
102 object for exclusive access to enqueue operations on that channel.
103 Then, they will submit one or more operations using
111 to drop their exclusive access to the channel.
112 The routine they provided for the
114 argument will be invoked with the provided
116 when the operation is complete.
118 For an example of usage, see
119 .Pa src/sys/dev/ioat/ioat_test.c .
122 .It Pa /dev/ioat_test
131 driver first appeared in
136 driver was developed by
137 .An \&Jim Harris Aq Mt jimharris@FreeBSD.org ,
139 .An \&Carl Delsey Aq Mt carl.r.delsey@intel.com .
140 This manual page was written by
141 .An \&Conrad Meyer Aq Mt cem@FreeBSD.org .
143 Copy operation takes bus addresses as parameters, not virtual addresses.
145 Copies larger than max transfer size (1MB) are not supported.
146 Future versions will likely support this by breaking up the transfer into
151 driver only supports copy and null operations at this time.
152 The driver does not yet support advanced DMA modes, such as XOR, that some
153 I/OAT devices support.