TCP as a module

TCP as a module

[Md. Islam]

Hi

Currently TCP is statically linked to the kernel. How can I make it a
loadable module? I need to modify TCP (tcp_input.c and tcp_output.c). It
would be easier for my development if it's just another module (I don't
need to restart every time).

I changed the *fs_initcall(inet_init)* to *module_init(inet_init)*, but
doesn't seem to help. Looking forward to your suggestions.

Many thanks
Tamim
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TCP as a module

[Valdis.Kletnieks at vt.edu]

On Sat, 05 Nov 2016 21:10:19 -0400, "Md. Islam" said:

> Currently TCP is statically linked to the kernel. How can I make it a
> loadable module? I need to modify TCP (tcp_input.c and tcp_output.c).

What problem are you trying to solve by modifying those two?  There
may be other approaches to do it.


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TCP as a module

[Aruna Hewapathirane]

> Currently TCP is statically linked to the kernel.

Correct, so how is this done and where ? Once you figure that part
out you have what you need to do what you want to :)

> How can I make it a loadable module?

Change into your source tree, look for this file:
linux-4.7.2/linux-4.7.2/net/Kconfig

Kconfig  is used by the KBuild system that menuconfig uses.

Look for the section:
config INET
bool "TCP/IP networking" <-- change bool to tristate, save and run make
menuconfig.

Now you can ask menuconfig to build TCP as a module.

But... it may be better to if you can use:
https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt

One last thing, heed the warnings in Kconfig they are there for a reason.

Good luck and what exactly are you trying to do ? Am curious.

Aruna ( Shrugs and gets ready to duck a flying trout Valdis may send my way
:)
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TCP as a module

[Md. Islam]

Hi Aruna

Thanks a lot! I changed the Kconfig to tristate and set the
config_INET=m. I also needed to add "depends on CONFIG_INET" to other
config options those depend on INET. I could build it. But when I
reboot,  I got the following error and it doesn't boot. Giving up :-(

error getting socket: Address family not supported by protocol
error initializing udev control socket

I'm trying to write a Media-friendly TCP (by implementing a new
option). Please let me know if you have any suggestion.

Many thanks
Tamim

On Mon, Nov 14, 2016 at 7:17 AM, Aruna Hewapathirane
<aruna.hewapathirane@gmail.com> wrote:
>> Currently TCP is statically linked to the kernel.
>
> Correct, so how is this done and where ? Once you figure that part
> out you have what you need to do what you want to :)
>
>> How can I make it a loadable module?
>
> Change into your source tree, look for this file:
> linux-4.7.2/linux-4.7.2/net/Kconfig
>
> Kconfig  is used by the KBuild system that menuconfig uses.
>
> Look for the section:
> config INET
> bool "TCP/IP networking" <-- change bool to tristate, save and run make
> menuconfig.
>
> Now you can ask menuconfig to build TCP as a module.
>
> But... it may be better to if you can use:
> https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt
>
> One last thing, heed the warnings in Kconfig they are there for a reason.
>
> Good luck and what exactly are you trying to do ? Am curious.
>
> Aruna ( Shrugs and gets ready to duck a flying trout Valdis may send my way
> :)



-- 
Tamim
PhD Student/Graduate Assistant
CS Department, Kent State University
Kent, OH 44240
http://web.cs.kent.edu/~mislam4/

TCP as a module

[Valdis.Kletnieks at vt.edu]

On Tue, 15 Nov 2016 00:14:43 -0500, "Md. Islam" said:

> I'm trying to write a Media-friendly TCP (by implementing a new
> option). Please let me know if you have any suggestion.

Step 0:  Figure out what the new option is, and why you think it will be
media-friendly.  Hint:  some 80% of internet traffic is streaming video, and
seems to be doing OK without any new options.  So you may want to double-check
what you're planning to achieve.  There's a pretty good chance that what you're
trying to do can *already* be done with an existing tunable parameter, or with
a traffic control module external to the main TCP stack (see the work on
fq_codel to stop bufferbloat for an example).

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