The patch titled
Document how to decode an IOCTL number
has been removed from the -mm tree. Its filename was
document-how-to-decode-an-ioctl-number.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: Document how to decode an IOCTL number
From: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Document how to decode a binary IOCTL number.
Signed-off-by: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
Documentation/ioctl/ioctl-decoding.txt | 24 +++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff -puN /dev/null Documentation/ioctl/ioctl-decoding.txt
--- /dev/null
+++ a/Documentation/ioctl/ioctl-decoding.txt
@@ -0,0 +1,24 @@
+To decode a hex IOCTL code:
+
+Most architecures use this generic format, but check
+include/ARCH/ioctl.h for specifics, e.g. powerpc
+uses 3 bits to encode read/write and 13 bits for size.
+
+ bits meaning
+ 31-30 00 - no parameters: uses _IO macro
+ 10 - read: _IOR
+ 01 - write: _IOW
+ 11 - read/write: _IOWR
+
+ 29-16 size of arguments
+
+ 15-8 ascii character supposedly
+ unique to each driver
+
+ 7-0 function #
+
+
+ So for example 0x82187201 is a read with arg length of 0x218,
+character 'r' function 1. Grepping the source reveals this is:
+
+#define VFAT_IOCTL_READDIR_BOTH _IOR('r', 1, struct dirent [2])
_
Patches currently in -mm which might be from 76306.1226@xxxxxxxxxxxxxx are
origin.patch
-
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