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32 .Nd Intel I/O Acceleration Technology
34 To compile this driver into your kernel,
35 place the following line in your kernel configuration file:
36 .Bd -ragged -offset indent
40 Or, to load the driver as a module at boot, place the following line in
42 .Bd -literal -offset indent
49 .Cd hw.ioat.force_legacy_interrupts=0
55 .Cd hw.ioat.enable_ioat_test=0
56 .Cd hw.ioat.debug_level=0
57 (only critical errors; maximum of 3)
60 .Fn (*bus_dmaengine_callback_t) "void *arg" "int error"
63 .Fn ioat_get_dmaengine "uint32_t channel_index"
65 .Fn ioat_put_dmaengine "bus_dmaengine_t dmaengine"
67 .Fn ioat_acquire "bus_dmaengine_t dmaengine"
69 .Fn ioat_release "bus_dmaengine_t dmaengine"
70 .Ft struct bus_dmadesc *
72 .Fa "bus_dmaengine_t dmaengine"
76 .Fa "bus_dmaengine_callback_t callback_fn"
77 .Fa "void *callback_arg"
80 .Ft struct bus_dmadesc *
82 .Fa "bus_dmaengine_t dmaengine"
84 .Fa "uint64_t fillpattern"
86 .Fa "bus_dmaengine_callback_t callback_fn"
87 .Fa "void *callback_arg"
90 .Ft struct bus_dmadesc *
92 .Fa "bus_dmaengine_t dmaengine"
93 .Fa "bus_dmaengine_callback_t callback_fn"
94 .Fa "void *callback_arg"
100 driver provides a kernel API to a variety of DMA engines on some Intel server
103 There is a number of DMA channels per CPU package.
105 Each may be used independently.
106 Operations on a single channel proceed sequentially.
108 Blockfill operations can be used to write a 64-bit pattern to memory.
110 Copy operations can be used to offload memory copies to the DMA engines.
112 Null operations do nothing, but may be used to test the interrupt and callback
115 All operations can optionally trigger an interrupt at completion with the
118 For example, a user might submit multiple operations to the same channel and
119 only enable an interrupt and callback for the last operation.
121 All operations are safe to use in a non-blocking context with the
124 (Of course, allocations may fail and operations requested with
128 All operations, as well as
129 .Fn ioat_get_dmaengine ,
130 can return NULL in special circumstances.
133 driver is being unloaded, or the administrator has induced a hardware reset, or
134 a usage error has resulted in a hardware error state that needs to be recovered
137 It is invalid to attempt to submit new DMA operations in a
138 .Fa bus_dmaengine_callback_t
141 A typical user will lookup the DMA engine object for a given channel with
142 .Fn ioat_get_dmaengine .
143 When the user wants to offload a copy, they will first
147 object for exclusive access to enqueue operations on that channel.
148 Then, they will submit one or more operations using
153 After queueing one or more individual DMA operations, they will
157 to drop their exclusive access to the channel.
158 The routine they provided for the
160 argument will be invoked with the provided
162 when the operation is complete.
163 When they are finished with the
164 .Ar bus_dmaengine_t ,
166 .Fn ioat_put_dmaengine .
168 Users MUST NOT block between
172 Users SHOULD NOT hold
174 references for a very long time to enable fault recovery and kernel module
177 For an example of usage, see
178 .Pa src/sys/dev/ioat/ioat_test.c .
181 .It Pa /dev/ioat_test
190 driver first appeared in
195 driver was developed by
196 .An \&Jim Harris Aq Mt jimharris@FreeBSD.org ,
197 .An \&Carl Delsey Aq Mt carl.r.delsey@intel.com ,
199 .An \&Conrad Meyer Aq Mt cem@FreeBSD.org .
200 This manual page was written by
201 .An \&Conrad Meyer Aq Mt cem@FreeBSD.org .
203 Copy operation takes bus addresses as parameters, not virtual addresses.
205 Buffers for individual copy operations must be physically contiguous.
207 Copies larger than max transfer size (1MB, but may vary by hardware) are not
209 Future versions will likely support this by breaking up the transfer into
214 driver only supports blockfill, copy, and null operations at this time.
215 The driver does not yet support advanced DMA modes, such as XOR, that some
216 I/OAT devices support.