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3 Using GCC's code coverage tool, gcov, with udev
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7 For more information on using gcov please see:
9 http://gcc.gnu.org/onlinedocs/gcc/Gcov.html
11 With that said, here is how to get code coverage analysis for udev files.
12 Note that this was developed with udev version 024.
14 - Make sure you've installed udev and that it is working properly.
15 If you are having problems, refer to the README and HOWTO-udev_for_dev
16 documents in udev tarball. I've also compiled a udev_for_dev
17 toubleshooting document for Red Hat which can be found at:
19 http://developer.osdl.org/ogasawara/gcov_for_udev/rh_udev_for_dev.txt
21 - Get the following files:
25 These can be found at http://developer.osdl.org/ogasawara/gcov_for_udev/
27 - After grabbing these files, copy both make_gcov.sh and run_gcov.sh
28 into the top level of your udev directory.
30 - execute make_gcov.sh
34 This will compile udev with gcov support. Basically make_gcov.sh will
35 run make but override the CFLAGS. It strips any optimization from
36 CFLAGS in order for gcov to get correct code coverage analysis. It will
37 also add the -fprofile-arcs and -ftest-coverage options which are the
38 necessary flags needed to use gcov.
40 make_gcov.sh will assume the same default parameters as the regular
41 make but also accepts the same parameters. For example if you want
42 to get code coverage analysis for udev with the DEBUG flag turned
43 on, you would just execute:
45 ./make_gcov.sh DEBUG=true
47 There is one exception, gcov will not work with klibc as it does not
48 compile cleanly with the -fprofile-arcs and -ftest-coverage flags.
49 With this said it is pretty much useless to set the KERNEL_DIR flag
50 when using make_gcov.sh as well.
52 Don't be alarmed if you look into your udev directory and see that it
53 has been polluted with a bunch of *.bb, *.bbg, *.da, and *.gcov files.
54 gcov creates and uses these files to extract the code coverage info.
56 - After running make_gcov.sh you need to install udev again. So basically,
61 - Then execute some udev tasks. You can run some udev tests, reboot, or
62 do anything your little udev heart desires. Once you are satisfied, you
63 can now see how much udev code was covered.
65 - To get the udev code coverage analysis, execute run_gcov.sh. You need to
71 - This creates udev_gcov.txt which holds all the code coverage information.
72 To see an example of the code coverage info after executing the udev-test.pl
75 http://developer.osdl.org/ogasawara/gcov_for_udev/udev_gcov.txt
77 - Also, after having executed gcov on udev (ie executing run_gcov.sh) a
78 *.gcov file is created for every file which contained code that was
79 used. Looking at the *.gcov files, one will see what lines of code
80 were hit, and what lines were missed. For, example if code in udev-add.c
81 were executed, gcov then created a file called udev-add.c.gcov. And a
82 portion of udev-add.c.gov might look like:
84 static int get_major_minor(struct sysfs_class_device *class_dev, struct udevice *udev)
86 95 struct sysfs_attribute *attr = NULL;
88 95 attr = sysfs_get_classdev_attr(class_dev, "dev");
91 dbg("dev='%s'", attr->value);
93 95 if (sscanf(attr->value, "%u:%u", &udev->major, &udev->minor) != 2)
95 dbg("found major=%d, minor=%d", udev->major, udev->minor);
102 Any line of code that is preceded by a "######" implies that the code
103 was never hit during execution.
105 - Once you are done with using gcov for udev and want to return to your
106 normal use of udev. Simply,
110 This will clean out all the *.bb, *.bbg, *.da, *.gcov files produced by gcov.
111 It will also run a regular make clean on your udev directory. Then just run
112 a regular make and make install and you are back to normal: