|
Am 14.02.2018 um 20:43 schrieb valdis.kletnieks@xxxxxx: No, make itself cannot generate dependency lists on its own, it needs tooling like gcc -MD ... to do that. I'm interested in a generic approach. But it my read and thus obey them.Doesn't "make" already do what you want? Well, unwanted dependencies could be excluded by a blacklist, although I still believe that at least most of the required shared libraries should rightfully be kept as dependencies, last but not least because libraries are changed occasionally only on a build server, making world builds rare as well.Oh, wait...dependency recording, because the "results" of running "ls -l" do depend on its shared libraries!This way lies madness - touch glibc or other package like that, and you just forced a rebuild of the entire world. In fact, I suspect that trying to follow "dependencies" to that level will result in build times close to what a 'make world' would do, because computing what ends up being the transitive closure of all file references is painful. Hint: To really do this correctly, you need to be able to force 100% code path coverage - otherwise you won't pick up the fact that /usr/lib64/libsnark.so is only actually used in an error path or similar rare-access corner case. I'm not so sure whether full coverage is really necessary. Instead, the depencency record of a full succesful initial build might be sufficient. Even considering other influencing things like the environment should be possible.For bonus points: openat(AT_FDCWD, "/usr/lib/locale/en_US.UTF-8/LC_MONETARY", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/usr/lib/locale/en_US.utf8/LC_MONETARY", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/usr/lib/locale/en_US.UTF-8/LC_TIME", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/usr/lib/locale/en_US.utf8/LC_TIME", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/usr/lib/locale/en_US.UTF-8/LC_NUMERIC", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/usr/lib/locale/en_US.utf8/LC_NUMERIC", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/usr/lib/locale/en_US.UTF-8/LC_CTYPE", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/usr/lib/locale/en_US.utf8/LC_CTYPE", O_RDONLY|O_CLOEXEC) = 3 Which file(s) count? How do you test for all values of $LANG and the various LC_* environment variables? There's a reason that most sane software builds and tools like rpm / dpkg and so on just check "glibc is still version 2.22" and don't bother going any further than that. And it just gets worse if you include kernel patches - how many modules end up involved in an open() call on a USB device? How do you detect that your code "depends" on a given behavior - often kernel patches address error conditions that doesn't change the perceived behavior in your userspace program... ... until a rare error condition arises. At this point, you need 100% code coverage of both the userspace *and* the kernel. You are most probably right with that, but I'd still like to continue pondering ... - as long as there is a way to yield the filename of an opened file using (fast) ftrace instead of slow ptrace?To quote the movie Animal House: "My advice to you is to start drinking heavily....." Thus, I'd still be interested in a solution or hint to my initial question.
|
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
