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Linux kernel WiMAX stack
(C) 2008 Intel Corporation < linux-wimax@intel.com >
This provides a basic Linux kernel WiMAX stack to provide a common
control API for WiMAX devices, usable from kernel and user space.
1. Design
The WiMAX stack is designed to provide for common WiMAX control
services to current and future WiMAX devices from any vendor.
Because currently there is only one and we don't know what would be the
common services, the APIs it currently provides are very minimal.
However, it is done in such a way that it is easily extensible to
accommodate future requirements.
The stack works by embedding a struct wimax_dev in your device's
control structures. This provides a set of callbacks that the WiMAX
stack will call in order to implement control operations requested by
the user. As well, the stack provides API functions that the driver
calls to notify about changes of state in the device.
The stack exports the API calls needed to control the device to user
space using generic netlink as a marshalling mechanism. You can access
them using your own code or use the wrappers provided for your
convenience in libwimax (in the wimax-tools package).
For detailed information on the stack, please see
include/linux/wimax.h.
2. Usage
For usage in a driver (registration, API, etc) please refer to the
instructions in the header file include/linux/wimax.h.
When a device is registered with the WiMAX stack, a set of debugfs
files will appear in /sys/kernel/debug/wimax:wmxX can tweak for
control.
2.1. Obtaining debug information: debugfs entries
The WiMAX stack is compiled, by default, with debug messages that can
be used to diagnose issues. By default, said messages are disabled.
The drivers will register debugfs entries that allow the user to tweak
debug settings.
Each driver, when registering with the stack, will cause a debugfs
directory named wimax:DEVICENAME to be created; optionally, it might
create more subentries below it.
2.1.1. Increasing debug output
The files named *dl_* indicate knobs for controlling the debug output
of different submodules of the WiMAX stack:
*
# find /sys/kernel/debug/wimax\:wmx0 -name \*dl_\*
/sys/kernel/debug/wimax:wmx0/wimax_dl_stack
/sys/kernel/debug/wimax:wmx0/wimax_dl_op_rfkill
/sys/kernel/debug/wimax:wmx0/wimax_dl_op_reset
/sys/kernel/debug/wimax:wmx0/wimax_dl_op_msg
/sys/kernel/debug/wimax:wmx0/wimax_dl_id_table
/sys/kernel/debug/wimax:wmx0/wimax_dl_debugfs
/sys/kernel/debug/wimax:wmx0/.... # other driver specific files
NOTE: Of course, if debugfs is mounted in a directory other than
/sys/kernel/debug, those paths will change.
By reading the file you can obtain the current value of said debug
level; by writing to it, you can set it.
To increase the debug level of, for example, the id-table submodule,
just write:
$ echo 3 > /sys/kernel/debug/wimax:wmx0/wimax_dl_id_table
Increasing numbers yield increasing debug information; for details of
what is printed and the available levels, check the source. The code
uses 0 for disabled and increasing values until 8.