Messages in this thread | | | Date | Wed, 11 Jun 2008 14:59:54 +0200 | From | Peter Oberparleiter <> | Subject | Re: [PATCH 0/6] gcov kernel support |
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Andrew Morton wrote: > On Mon, 09 Jun 2008 15:49:16 +0200 Peter Oberparleiter <peter.oberparleiter@de.ibm.com> wrote: > >> Andrew Morton wrote: >> > On Mon, 02 Jun 2008 15:33:51 +0200 Peter Oberparleiter <peter.oberparleiter@de.ibm.com> wrote: >> > >> >> This is version #3 of the gcov kernel support patch set >> > >> > My build tree is now filled with dead symlinks, like >> > >> > lrwxrwxrwx 1 akpm akpm 64 Jun 9 00:06 security/selinux/nlmsgtab.gcda -> /sys/kernel/debug/gcov/usr/src/25/security/selinux/nlmsgtab.gcda >> >> Unfortunately a necessary evil of this approach: symlinks are created >> for all compiled source files while link targets are only available when >> the corresponding code is executed. In other words: those links will be >> dead for source files which don't compile to actual code and for modules >> as long as they are not loaded. > > It doesn't seem awfully useful. I don't run kernels on my build > machines and I'm sure many are in the same situation. So gcov is going > to need a way of locating these files on the *target* machine. And > once that is available, there is no need to add all these symlinks into > the build directory.
I don't see any other feasibly way to do it if we want the kernel to work out-of-the-box with gcov. If the kernel was a user-space application, gcc/libgcov would create the .gcda files in exactly the same place where the symbolic links are now.
If we removed those symlinks, users would have to manually copy files from /sys on the test machine to the correct position in /objtree on the build machine before being able to get any kind of result. This would IMO reduce the usefulness of the gcov kernel infrastructure noticeably (though gcov-wrappers such as lcov could be modified to hide the additional effort).
How about a CONFIG_GCOV_PROFILE_SYMLINKS configuration option?
>> > Which causes (at least) >> > >> > ctags: Warning: cannot open source file "security/selinux/ss/conditional.gcda" : No such file or directory >> > ctags: Warning: cannot open source file "security/selinux/netlink.gcda" : No such file or directory >> > ctags: Warning: cannot open source file "security/selinux/netlabel.gcda" : No such file or directory >> >> > and probably other thing which I haven't discovered yet.
I would argue that any mechanism that tries to access all files in /objtree regardless of filename extension is brave at best, if not broken.
>> I'm sure there's some kind of 'find' magic that can be used to work >> around dead links. I'll see how this can be applied to the ctags case - >> though neither 'make tags' nor 'make TAGS' seem to produce any warnings >> on my system.. > > I use > > ctags -R --excmd=pattern --format=1
ctags -R --excmd=pattern --format=1 --exclude=\*.gcda
:)
Regards, Peter
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