Lines Matching +full:dma +full:- +full:requests
2 Using physical DMA provided by OHCI-1394 FireWire controllers for debugging
6 ------------
9 to the OHCI-1394 specification which defines the controller to be a PCI
10 bus master which uses DMA to offload data transfers from the CPU and has
11 a "Physical Response Unit" which executes specific requests by employing
12 PCI-Bus master DMA after applying filters defined by the OHCI-1394 driver.
14 Once properly configured, remote machines can send these requests to
15 ask the OHCI-1394 controller to perform read and write requests on
16 physical system memory and, for read requests, send the result of
28 more common hardware such as x86, x86-64 and PowerPC.
34 Together with a early initialization of the OHCI-1394 controller for debugging,
41 -------
43 The firewire-ohci driver in drivers/firewire uses filtered physical
44 DMA by default, which is more secure but not suitable for remote debugging.
45 Pass the remote_dma=1 parameter to the driver to get unfiltered physical DMA.
47 Because the firewire-ohci driver depends on the PCI enumeration to be
57 -----
59 firescope - Originally developed by Benjamin Herrenschmidt, Andi Kleen ported
63 Bernhard Kaindl enhanced firescope to support accessing 64-bit machines
64 from 32-bit firescope and vice versa:
65 - http://v3.sk/~lkundrak/firescope/
67 and he implemented fast system dump (alpha version - read README.txt):
68 - http://halobates.de/firewire/firedump-0.1.tar.bz2
72 - http://halobates.de/firewire/fireproxy-0.33.tar.bz2
74 The latest version of this gdb proxy (fireproxy-0.34) can communicate (not
75 yet stable) with kgdb over an memory-based communication module (kgdbom).
78 ---------------
80 The OHCI-1394 specification regulates that the OHCI-1394 controller must
81 disable all physical DMA on each bus reset.
84 interrupts are disabled and where no polling of the OHCI-1394 controller
89 Step-by-step instructions for using firescope with early OHCI initialization:
93 Load the firewire-ohci module and check your kernel logs.
100 CardBus and even some Express cards which are fully compliant to OHCI-1394
108 required for physical DMA above 4 GB (but not utilized by Linux yet).
113 stable connection and has matching connectors (there are small 4-pin and
114 large 6-pin FireWire ports) will do.
123 3) Test physical DMA using firescope:
132 ---------
135 [Ctrl-T] choose target
136 [Ctrl-H] this menu
137 [Ctrl-Q] quit
139 ------> Press Ctrl-T now, the output should be similar to:
147 4) Prepare for debugging with early OHCI-1394 initialization:
152 (Kernel hacking: Provide code for enabling DMA over FireWire early on boot)
162 With the FireWire cable connected, the OHCI-1394 driver on the debugging
166 Then, on the debugging host, run firescope, for example by using -A::
168 firescope -A System.map-of-debug-target-kernel
170 Note: -A automatically attaches to the first non-local node. It only works
173 After having attached to the debug target, press Ctrl-D to view the
174 complete printk buffer or Ctrl-U to enter auto update mode and get an
177 Call "firescope -h" to get more information on firescope's options.
180 -----
184 FireWire is a trademark of Apple Inc. - for more information please refer to: