# mount -t debugfs none_debugs /sys/kernel/debug
# modprobe usbmon
+#
Verify that bus sockets are present.
-[root@lembas zaitcev]# ls /sys/kernel/debug/usbmon
+# ls /sys/kernel/debug/usbmon
1s 1t 2s 2t 3s 3t 4s 4t
-[root@lembas zaitcev]#
-
-# ls /sys/kernel
+#
2. Find which bus connects to the desired device
* Raw text data format
-The '0t' type data consists of a stream of events, such as URB submission,
+The '1t' type data consists of a stream of events, such as URB submission,
URB callback, submission error. Every event is a text line, which consists
of whitespace separated words. The number of position of words may depend
on the event type, but there is a set of words, common for all types.
Zi Zo Isochronous input and output
Ii Io Interrupt input and output
Bi Bo Bulk input and output
- Device address and Endpoint number are decimal numbers with leading zeroes
- or 3 and 2 positions, correspondingly.
-- URB Status. This field makes no sense for submissions, but is present
- to help scripts with parsing. In error case, it contains the error code.
-- Data Length. This is the actual length in the URB.
+ Device address and Endpoint number are 3-digit and 2-digit (respectively)
+ decimal numbers, with leading zeroes.
+- URB Status. In most cases, this field contains a number, sometimes negative,
+ which represents a "status" field of the URB. This field makes no sense for
+ submissions, but is present anyway to help scripts with parsing. When an
+ error occurs, the field contains the error code. In case of a submission of
+ a Control packet, this field contains a Setup Tag instead of an error code.
+ It is easy to tell whether the Setup Tag is present because it is never a
+ number. Thus if scripts find a number in this field, they proceed to read
+ Data Length. If they find something else, like a letter, they read the setup
+ packet before reading the Data Length.
+- Setup packet, if present, consists of 5 words: one of each for bmRequestType,
+ bRequest, wValue, wIndex, wLength, as specified by the USB Specification 2.0.
+ These words are safe to decode if Setup Tag was 's'. Otherwise, the setup
+ packet was present, but not captured, and the fields contain filler.
+- Data Length. For submissions, this is the requested length. For callbacks,
+ this is the actual length.
- Data tag. The usbmon may not always capture data, even if length is nonzero.
- Only if tag is '=', the data words are present.
+ The data words are present only if this tag is '='.
- Data words follow, in big endian hexadecimal format. Notice that they are
not machine words, but really just a byte stream split into words to make
it easier to read. Thus, the last word may contain from one to four bytes.
String data_str = st.nextToken();
int len = data_str.length() / 2;
int i;
+ int b; // byte is signed, apparently?! XXX
for (i = 0; i < len; i++) {
- data[data_len] = Byte.parseByte(
- data_str.substring(i*2, i*2 + 2),
- 16);
+ // data[data_len] = Byte.parseByte(
+ // data_str.substring(i*2, i*2 + 2),
+ // 16);
+ b = Integer.parseInt(
+ data_str.substring(i*2, i*2 + 2),
+ 16);
+ if (b >= 128)
+ b *= -1;
+ data[data_len] = (byte) b;
data_len++;
}
}
}
}
-This format is obviously deficient. For example, the setup packet for control
-transfers is not delivered. This will change in the future.
+This format may be changed in the future.
Examples:
-An input control transfer to get a port status:
+An input control transfer to get a port status.
-d74ff9a0 2640288196 S Ci:001:00 -115 4 <
-d74ff9a0 2640288202 C Ci:001:00 0 4 = 01010100
+d5ea89a0 3575914555 S Ci:001:00 s a3 00 0000 0003 0004 4 <
+d5ea89a0 3575914560 C Ci:001:00 0 4 = 01050000
An output bulk transfer to send a SCSI command 0x5E in a 31-byte Bulk wrapper
to a storage device at address 5:
git://git.onelab.eu / linux-2.6.git / blobdiff