Thread: How to add .o file in the Linux Kernel

This has little to do with C programming. This is the kernel build process.

And the person helping you couldn't have put it clearer. Running "make xconfig" or "make menuconfig" or whatever generates a file named ".config" inside the kernel source folder. That file is built from all the Kconfig segments. When you edit that file (".config", which is hidden by default because of the "." in the filename), and then do a normal "make", you can change what the kernel build actually builds (i.e. which modules it uses).

But, honestly, if you couldn't work out that much, I don't see you getting much further in kernel programming without a LOT of help, and there the kernel mailing lists and other support are more useful for you.

Originally Posted by memcpy

Stop trying to modify the Linux kernel if you don't understand what it's doing. Stop trying to change the TCP stack because it won't help performance. Stop posting threads about it here because these types of questions are best suited for a mailing list about your specific OS.

Agreed. Ambition is nice. Messing with your TCP stack in kernel space when you can't even work out how the Makefile works, or what a ".config" file is - that's just stupidity. And from the impression I get, I severely doubt you will be able to do anything that will actually provide any measurable difference because you don't even seem to understand much of what the TCP stack is actually doing. Honestly, do you know what SYN-cookies are without Googling it? Do you know understand window-scaling, or exponential backoff, or Nagle's algorithm, or congestion control? At one point you mention a research partner - if this really is part of serious research, I struggle to believe you can't find out a couple of things like "how to compile a kernel", "how to edit a kernel build config", etc. on your own and within about 5-10 minutes each.

I refer the OP to my comment in his other thread (didn't realise it was the same person): Where is the TCP source code in Ubuntu 10.04?

For what you're trying to do, all we hear in this forum is the equivalent of "Hey, I've heard you can make engines run faster using nitroglycerine. I've got a car, so I thought I'd do it." - that's not so bad until you then see your other threads like this which are the equivalent of "What's a car?", "What's an accelerator?", "What's nitroglycerine?", "I poured some nitro in the tank and it just want bang" and, now, "Okay, so how do I put this nitroglycerine into a piston?".

I've been programming for about 15 years, and managed Linux systems for most of that time (personal and professional). The few times I've ever needed to play with kernel source, I used high quality, highly tested, highly sanitised code that was developed out-of-tree by people who spend their life on such code and was merely marked as "test" code. I have had literally a handful of occasions where it was necessary to edit that code (usually to compensate for some mechanism like locking or hardware access that had changed between kernels, and I just updated the patch with some obvious - but still hacky - changes to "just make it work" quickly until a real patch came out). In terms of working out what file to edit, how to compile it, how to get a working module out of it, etc. it was literally ten minutes of research the first time. In terms of actually generating code that didn't crash-and-burn, lock-up or not work at all, it took hours for even the simplest of changes and there's no way I would ever pass my modified patches off as anything other than a quick hack.

Honestly, curiosity, learning and experimentation are great. But it's taken you two months to work out how to build a kernel with a single modified .c file - and in the process you didn't realise that you couldn't use floating point in kernel-space, didn't realise that the errors thrown by that WERE because you didn't have floating point functions available, didn't realise that a /proc virtual file you wanted to use didn't actually exists (and thus you were baffled that echo'ing it returned a filesystem error), and lots of other things that you obviously didn't even bother to Google to find out the reason behind, much less understand the reason by your own introspection.

This is a C forum. You have a kernel project. Although you seem to have a grasp of C (albeit lazy and incomplete in terms of real-world errors), you obviously have no grasp of Linux kernel coding at all. Maybe you should stop asking in a C forum and follow the advice given to you by countless people - go find a kernel programming mailing list, forum, or other source of support for your questions which almost exclusively pertain to Linux kernel programming specifically. Hell, even a TCP programming forum would probably be more relevant to your problems.

That said, if this is a research project of any note, I would have to say that it's an incredibly lazy and slow-progressing one where you want other people to notice, interpret and fix your own schoolboy errors.