Kernel question

[imgr8]

I am new to debian and linux. Basically I am taking an Operating System Design class and we were asked to download the source code for linux and compile it and boot ubuntu (ubuntu 9.10 on VMWare) with it. I downloaded the newest kernel source code available : linux-2.6.33.2 and compiled it by following instructions at http://www.howtogeek.com/howto/ubuntu/h ... tu-kernel/ It took 6 hours to compile and it created 2 debian files in /usr/src called linux-headers-2.6.31-custom_2.6.31-custom-10.00.Custom_i386.deb and linux-image-2.6.31-custom_2.6.31-custom-10.00.Custom_i386.deb

Now the problem I have is in the next step: The command

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dpkg -i linux-image-2.6.31-custom_2.6.31-custom-10.00.Custom_i386.deb

works fine and finishes without any errors but when I run

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dpkg -i linux-headers-2.6.31-custom_2.6.31-custom-10.00.Custom_i386.deb

It gives

(Reading database ... 173297 files and directories currently installed.)
Preparing to replace linux-headers-2.6.31-custom 2.6.31-custom-10.00.Custom (using linux-headers-2.6.31-custom_2.6.31-custom-10.00.Custom_i386.deb) ...
Unpacking replacement linux-headers-2.6.31-custom ...
Setting up linux-headers-2.6.31-custom (2.6.31-custom-10.00.Custom) ...
dpkg: warning: obsolete option '--print-installation-architecture', please use '--print-architecture' instead.

and it stops. Is there a way to get around this? I do see a linux-headers-2.6.31-custom folder created in the /usr/src directory.

[AdrianTM]

I think it's installed, the message that you get "dpkg: warning:" is just that, a "warning".

[imgr8]

But when I do a uname -r it says "2.6.31-20-generic" instead of saying custom. Should I manually switch to the custom one?

[AdrianTM]

But when I do a uname -r it says "2.6.31-20-generic" instead of saying custom. Should I manually switch to the custom one?

No, because it's installed but you need to boot into it, you need first to add it to GRUB menu ("update-grub" might do the trick, if not you need to add it manually) and then reboot and select the new option.

[imgr8]

Thanks! Will try that now

[stevepusser]

It's also possible, even safer, to build your kernel debs as a regular user in any folder you pick in your home, instead of messing around in /usr/src. Just install fakeroot and add it to the kernel building command, i.e.:

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CONCURRENCY_LEVEL=`getconf _NPROCESSORS_ONLN` fakeroot make-kpkg --initrd --append-to-version=-custom kernel_image kernel_headers

The stuff before fakeroot determines how many cores or cpus you have and uses them to maximum capacity...kind of useless if you only have one core or are using a virtual machine.

[AdrianTM]

I still haven't found a valid explanation why is bad to use /usr/src I can add myself to src group and then be able to edit files there as simple user and build the kernel with fakeroot, why would building in my home be better?

And if I build in my home the /lib/modules will point there instead of /usr/src/linux...

[nadir]

And if I build in my home the /lib/modules will point there instead of /usr/src/linux...

http://forums.debian.net/viewtopic.php? ... 15#p281296

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cd /lib/modules/<kernel-version>
ln -nsf /usr/src/linux-headers-<kernel-version> build
ln -nsf /usr/src/linux-headers-<kernel-version> source

I think, that's how i did understand it.

[AdrianTM]

And if I build in my home the /lib/modules will point there instead of /usr/src/linux...

http://forums.debian.net/viewtopic.php? ... 15#p281296

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cd /lib/modules/<kernel-version>
ln -nsf /usr/src/linux-headers-<kernel-version> build
ln -nsf /usr/src/linux-headers-<kernel-version> source

I think, that's how i did understand it.

Ok, that makes sense, but still, I don't see any problem with using /usr/src if you add yourself for src group and use fakeroot...

[nadir]

Well: me know it neither, that's for sure.
There are some threads/posts about the why or rather why not, but i don't understand them. The users who advice so sound trustworthy.

[stevepusser]

It's relatively safe to build in /usr/src if you know what you are doing, but really, why do it in a system folder when you don't have to? I always had to create new links to the header folder instead of /usr/src/linux anyway, no matter where I built it. I think if you rename the build folder before installing the debs, the installer will create the correct links to the header files if it can't find the source folder...which is hundreds of times bigger than the headers folder, you have to use compiled source to build modules without the headers, I hear.