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+################################################
+
+Using GCC's code coverage tool, gcov, with udev
+
+################################################
+
+For more information on using gcov please see:
+
+http://gcc.gnu.org/onlinedocs/gcc/Gcov.html
+
+With that said, here is how to get code coverage analysis for udev files.
+Note that this was developed with udev version 024.
+
+- Make sure you've installed udev and that it is working properly.
+ If you are having problems, refer to the README and HOWTO-udev_for_dev
+ documents in udev tarball. I've also compiled a udev_for_dev
+ toubleshooting document for Red Hat which can be found at:
+
+ http://developer.osdl.org/ogasawara/gcov_for_udev/rh_udev_for_dev.txt
+
+- Get the following files:
+ make_gcov.sh
+ run_gcov.sh
+
+ These can be found at http://developer.osdl.org/ogasawara/gcov_for_udev/
+
+- After grabbing these files, copy both make_gcov.sh and run_gcov.sh
+ into the top level of your udev directory.
+
+- execute make_gcov.sh
+
+ ./make_gcov.sh
+
+ This will compile udev with gcov support. Basically make_gcov.sh will
+ run make but override the CFLAGS. It strips any optimization from
+ CFLAGS in order for gcov to get correct code coverage analysis. It will
+ also add the -fprofile-arcs and -ftest-coverage options which are the
+ necessary flags needed to use gcov.
+
+ make_gcov.sh will assume the same default parameters as the regular
+ make but also accepts the same parameters. For example if you want
+ to get code coverage analysis for udev with the DEBUG flag turned
+ on, you would just execute:
+
+ ./make_gcov.sh DEBUG=true
+
+ There is one exception, gcov will not work with klibc as it does not
+ compile cleanly with the -fprofile-arcs and -ftest-coverage flags.
+ With this said it is pretty much useless to set the KERNEL_DIR flag
+ when using make_gcov.sh as well.
+
+ Don't be alarmed if you look into your udev directory and see that it
+ has been polluted with a bunch of *.bb, *.bbg, *.da, and *.gcov files.
+ gcov creates and uses these files to extract the code coverage info.
+
+- After running make_gcov.sh you need to install udev again. So basically,
+
+ su to root
+ make install
+
+- Then execute some udev tasks. You can run some udev tests, reboot, or
+ do anything your little udev heart desires. Once you are satisfied, you
+ can now see how much udev code was covered.
+
+- To get the udev code coverage analysis, execute run_gcov.sh. You need to
+ be root to do this.
+
+ su to root
+ ./run_gcov.sh
+
+- This creates udev_gcov.txt which holds all the code coverage information.
+ To see an example of the code coverage info after executing the udev-test.pl
+ test, please see:
+
+ http://developer.osdl.org/ogasawara/gcov_for_udev/udev_gcov.txt
+
+- Also, after having executed gcov on udev (ie executing run_gcov.sh) a
+ *.gcov file is created for every file which contained code that was
+ used. Looking at the *.gcov files, one will see what lines of code
+ were hit, and what lines were missed. For, example if code in udev-add.c
+ were executed, gcov then created a file called udev-add.c.gcov. And a
+ portion of udev-add.c.gov might look like:
+
+ static int get_major_minor(struct sysfs_class_device *class_dev, struct udevice *udev)
+ 95 {
+ 95 struct sysfs_attribute *attr = NULL;
+
+ 95 attr = sysfs_get_classdev_attr(class_dev, "dev");
+ 95 if (attr == NULL)
+ ###### goto error;
+ dbg("dev='%s'", attr->value);
+
+ 95 if (sscanf(attr->value, "%u:%u", &udev->major, &udev->minor) != 2)
+ ###### goto error;
+ dbg("found major=%d, minor=%d", udev->major, udev->minor);
+
+ 95 return 0;
+ error:
+ ###### return -1;
+ }
+
+ Any line of code that is preceded by a "######" implies that the code
+ was never hit during execution.
+
+- Once you are done with using gcov for udev and want to return to your
+ normal use of udev. Simply,
+
+ ./make_gcov.sh clean
+
+ This will clean out all the *.bb, *.bbg, *.da, *.gcov files produced by gcov.
+ It will also run a regular make clean on your udev directory. Then just run
+ a regular make and make install and you are back to normal:
+
+ make
+ su to root
+ make isntall