some kernel compilation questions

[elovkoff]

I have some questions regarding the efficient kernel compilation :

1. Let's say I want to add some features to existing kernel like netfilter support. I compiled another kernel, but what I actually wanted to do was to add it to existing one. Is ther any way to re-compile existing kernel with netfilter support instead of compiling a new one from the scratch?
2. Is there any way to add netfilter support to the kernel during the red hat installation? (The idea of installing red hat and recompiling the kernel after that to include the netfilter support doesn't look very peachy to me
3. Will iptables function normally (NAT, rules, etc) without installing netfilter support?
thx.

[Feztaa]

1. Let's say I want to add some features to existing kernel like netfilter support. I compiled another kernel, but what I actually wanted to do was to add it to existing one. Is ther any way to re-compile existing kernel with netfilter support instead of compiling a new one from the scratch?

What do you mean? When you compile a kernel, you compile a kernel. You can't "add features" to an existing kernel unless you used module support and loaded modules into it.

2. Is there any way to add netfilter support to the kernel during the red hat installation? (The idea of installing red hat and recompiling the kernel after that to include the netfilter support doesn't look very peachy to me

Frankly, I'm shocked and appaled that the stock kernel with redhat doesn't have netfilter support. I mean, even mandrake's stock kernel has it! *sigh* :

3. Will iptables function normally (NAT, rules, etc) without installing netfilter support?

No, netfilter won't work without netfilter support.

[elovkoff]

What do you mean? When you compile a kernel, you compile a kernel. You can't "add features" to an existing kernel unless you used module support and loaded modules into it.

O.K.-this is what I mean:
When I do a compilation of the kernel I can save configuration to the file,right? And later on if I want to add the feature to that kernel all I have to do is to open make xconfig and load the configuration file and then add some featues.
I was wondering if there is such a config file for EXISTING kernel that I can load and add netfilter support instead of compiling the new kernel......
The logic is pretty simple-when I compile a new kernel I have to choose all the options myself, and no matter how long I dig help in make xconfig I still am not sure that I added all features needed for the new kernel, so the easiest thing would be for me to take the existing kernel and add some features (like netfilter) to it-I just don't know if it possible.

As to the fact that rh kernel doesn't have a netfilter support out of the box-I must agree 100% that this is absolutely weird.

[stryder144]

O.K.-this is what I mean:
When I do a compilation of the kernel I can save configuration to the file,right? And later on if I want to add the feature to that kernel all I have to do is to open make xconfig and load the configuration file and then add some featues.
I was wondering if there is such a config file for EXISTING kernel that I can load and add netfilter support instead of compiling the new kernel......
The logic is pretty simple-when I compile a new kernel I have to choose all the options myself, and no matter how long I dig help in make xconfig I still am not sure that I added all features needed for the new kernel, so the easiest thing would be for me to take the existing kernel and add some features (like netfilter) to it-I just don't know if it possible.

As to the fact that rh kernel doesn't have a netfilter support out of the box-I must agree 100% that this is absolutely weird.

If I understand you correctly, then the answer to your question is no. You must recompile the kernel and add the modules/features that you are looking for. Sad, but true.

[elovkoff]

Let me rephrase it
Is it correct to say that when I issue make xconfig then the current kernel config is brought up? (and I just have to add some featrures to it...)

[stryder144]

Let me rephrase it
Is it correct to say that when I issue make xconfig then the current kernel config is brought up? (and I just have to add some featrures to it...)

Yes, but you will still need to recompile the kernel. If I am not mistaken, you can do the whole shebang (config, make, blah blah) and once the kernel finishes recompiling, you just reboot. I don't think that you will have to mess with lilo, as it should be pointing to your kernel already. I think that if you recompile the kernel it is kinda like reshuffling a deck of cards. Can someone clarify that point? I don't want to have too great a hand in hosing elovkoff's system.

Check out the PET on compiling the kernel by pbharris at this link http://www.linuxjunior.org/cgi-bin/p...splay&id=9. There is a link at the bottom which should bring you to the kernel compiling how-to. That one should have more info on recompiling a kernel (which is a little different process than compiling a new kernel).

I hope that I have not steered you wrong and that I have been helpful.

Cheers.

[Feztaa]

When I do a compilation of the kernel I can save configuration to the file,right? And later on if I want to add the feature to that kernel all I have to do is to open make xconfig and load the configuration file and then add some featues.

Yes, you can save the kernel config, then load it again next time you compile, if you only want to change some things, and not start from scratch.

If you are asking if make xconfig shows the configuration of the kernel that is currently running - No.

I was wondering if there is such a config file for EXISTING kernel that I can load and add netfilter support instead of compiling the new kernel......

No. You can't compile features into the kernel without compiling a new one.

You can, however, compile things as modules, and then load them at runtime.

[Gaenya]

By default your config is saved in a file called /path/to/your/kernelsource/.config, you just have to save that file and you dont have to start from scratch with your kernels.

HtH

[Vagrant]

What do you mean it doesnt have netfilter support? .. it does, thats like one of the most major aspects of 2.4 .. do a 'locate netfilter' and you'll see .. or do you have a very old version of rh? ..
*Vagrant

[rick420]

I know exactly what you mean, check out this: www.high-on-linux.net/kernel.html