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-rw-r--r--Documentation/trace/mmiotrace.txt15
1 files changed, 8 insertions, 7 deletions
diff --git a/Documentation/trace/mmiotrace.txt b/Documentation/trace/mmiotrace.txt
index 162effbfbde..664e7386d89 100644
--- a/Documentation/trace/mmiotrace.txt
+++ b/Documentation/trace/mmiotrace.txt
@@ -44,7 +44,8 @@ Check for lost events.
44Usage 44Usage
45----- 45-----
46 46
47Make sure debugfs is mounted to /sys/kernel/debug. If not, (requires root privileges) 47Make sure debugfs is mounted to /sys/kernel/debug.
48If not (requires root privileges):
48$ mount -t debugfs debugfs /sys/kernel/debug 49$ mount -t debugfs debugfs /sys/kernel/debug
49 50
50Check that the driver you are about to trace is not loaded. 51Check that the driver you are about to trace is not loaded.
@@ -91,7 +92,7 @@ $ dmesg > dmesg.txt
91$ tar zcf pciid-nick-mmiotrace.tar.gz mydump.txt lspci.txt dmesg.txt 92$ tar zcf pciid-nick-mmiotrace.tar.gz mydump.txt lspci.txt dmesg.txt
92and then send the .tar.gz file. The trace compresses considerably. Replace 93and then send the .tar.gz file. The trace compresses considerably. Replace
93"pciid" and "nick" with the PCI ID or model name of your piece of hardware 94"pciid" and "nick" with the PCI ID or model name of your piece of hardware
94under investigation and your nick name. 95under investigation and your nickname.
95 96
96 97
97How Mmiotrace Works 98How Mmiotrace Works
@@ -100,7 +101,7 @@ How Mmiotrace Works
100Access to hardware IO-memory is gained by mapping addresses from PCI bus by 101Access to hardware IO-memory is gained by mapping addresses from PCI bus by
101calling one of the ioremap_*() functions. Mmiotrace is hooked into the 102calling one of the ioremap_*() functions. Mmiotrace is hooked into the
102__ioremap() function and gets called whenever a mapping is created. Mapping is 103__ioremap() function and gets called whenever a mapping is created. Mapping is
103an event that is recorded into the trace log. Note, that ISA range mappings 104an event that is recorded into the trace log. Note that ISA range mappings
104are not caught, since the mapping always exists and is returned directly. 105are not caught, since the mapping always exists and is returned directly.
105 106
106MMIO accesses are recorded via page faults. Just before __ioremap() returns, 107MMIO accesses are recorded via page faults. Just before __ioremap() returns,
@@ -122,11 +123,11 @@ Trace Log Format
122---------------- 123----------------
123 124
124The raw log is text and easily filtered with e.g. grep and awk. One record is 125The raw log is text and easily filtered with e.g. grep and awk. One record is
125one line in the log. A record starts with a keyword, followed by keyword 126one line in the log. A record starts with a keyword, followed by keyword-
126dependant arguments. Arguments are separated by a space, or continue until the 127dependent arguments. Arguments are separated by a space, or continue until the
127end of line. The format for version 20070824 is as follows: 128end of line. The format for version 20070824 is as follows:
128 129
129Explanation Keyword Space separated arguments 130Explanation Keyword Space-separated arguments
130--------------------------------------------------------------------------- 131---------------------------------------------------------------------------
131 132
132read event R width, timestamp, map id, physical, value, PC, PID 133read event R width, timestamp, map id, physical, value, PC, PID
@@ -136,7 +137,7 @@ iounmap event UNMAP timestamp, map id, PC, PID
136marker MARK timestamp, text 137marker MARK timestamp, text
137version VERSION the string "20070824" 138version VERSION the string "20070824"
138info for reader LSPCI one line from lspci -v 139info for reader LSPCI one line from lspci -v
139PCI address map PCIDEV space separated /proc/bus/pci/devices data 140PCI address map PCIDEV space-separated /proc/bus/pci/devices data
140unk. opcode UNKNOWN timestamp, map id, physical, data, PC, PID 141unk. opcode UNKNOWN timestamp, map id, physical, data, PC, PID
141 142
142Timestamp is in seconds with decimals. Physical is a PCI bus address, virtual 143Timestamp is in seconds with decimals. Physical is a PCI bus address, virtual