EBC Exercise 26 Device Drivers - Revision history

Lobdeljt at 05:47, 5 November 2012

2012-11-05T05:47:06Z

2012-10-30T08:30:23Z

‎Compiling

2012-10-18T13:55:25Z

‎Compiling

2012-07-17T19:34:48Z

2012-05-29T14:30:38Z

‎Optional Driver Work

2012-05-28T17:40:56Z

Added Header/Footer

2012-02-07T21:24:05Z

‎Compiling

2012-01-31T13:02:00Z

‎Moving to Beagle: Added editing modules.dep

2012-01-24T17:08:07Z

‎Driver Methods: Made last part optional

2012-01-05T16:17:42Z

@@ Line 43: / Line 43: @@
 </pre>
 This will properly unregister the module from the kernel and allow it to be inserted and removed from the kernel at will without restarting your system in between.
 === Moving to Beagle ===

@@ Line 25: / Line 25: @@
 This will create '''lib''' directory in '''~/BeagleBoard''' with everything that goes in '''/lib''' on the Beagle. Then
-  host$ '''scp –r ~/BeagleBoard/lib root@beagle:/lib'''
+  host$ '''rsync --progress -avhe ssh ~/BeagleBoard/lib root@beagle:/'''
 Could take a while to transfer.

@@ Line 14: / Line 14: @@
 If you have created the '''crossCompileEnv.sh''' file and sourced it, all you have to do to make the modules is cd to the top of the kernel directory and then:
-  host$ '''make modules'''
+ host$ '''source ~/.oe/crossCompileEnv.sh'''  (Only need to run once per terminal session.)
 Mine took a while the first time as it compiles all the modules. The second it only took 31 seconds.

@@ Line 117: / Line 117: @@
 * How can your driver find what the minor device number is?
 * Modify the driver to return some characters when <code>/dev/hello1</code> is read.
 {{YoderFoot}}

@@ Line 1: / Line 1: @@
 [[Category:ECE497]]
 Chapter 8 of the text [http://www.amazon.com/Embedded-Linux-Primer-Practical-Real-World/dp/0137017839] gives a nice example of a minimal device driver.  The purpose of this lab is to implement that driver.
@@ Line 116: / Line 117: @@
 * How can your driver find what the minor device number is?
 * Modify the driver to return some characters when <code>/dev/hello1</code> is read.

← Older revision		Revision as of 21:24, 7 February 2012
Line 16:		Line 16:

	Mine took a while the first time as it compiles all the modules. The second it only took 31 seconds.		Mine took a while the first time as it compiles all the modules. The second it only took 31 seconds.
		+
		+	If you want to install all the modules that are created.
		+
		+	host$ '''make INSTALL_MOD_PATH=~/BeagleBoard modules_install'''
		+
		+	This will create '''lib''' directory in '''~/BeagleBoard''' with everything that goes in '''/lib''' on the Beagle. Then
		+
		+	host$ '''scp –r ~/BeagleBoard/lib root@beagle:/lib'''
		+
		+	Could take a while to transfer.

	====Improvements to the Code in the Book====		====Improvements to the Code in the Book====

@@ Line 45: / Line 45: @@
 I suggest putting the <code>scp</code> command in the <code>Makefile</code> since you may use it several times while developing your code.
-Now, on the Beagle, modprobe the module and check the log file.
+Now, on the Beagle, add the module to '''modules.dep'''
-  beagle$ '''/sbin/modprobe hello1'''
+  beagle$ '''cd /lib/modules/2.6.32'''
   beagle$ '''dmesg | tail -4'''
 You should see your Init message.  And then...
-  beagle$ '''/sbin/modprobe -r hello1'''
+  beagle$ '''modprobe -r hello1'''
   beagle$ '''dmesg | tail -4'''

@@ Line 81: / Line 81: @@
 * What does <code>mknod</code> do?
 * Once your device is running try <code>$ cat /proc/devices</code>.  Do you see your device?
 Chapter 3 of ''Linux Device Drivers'' by Corbet, Rubini and Kroah-Hartman ([http://www.rose-hulman.edu/~yoder/Beagle/]) gives some more details on device drivers. Our text uses an older, static, method for major device number allocation.  The book, referenced above, uses the newer dynamic allocation.