compiling kernel 3.14.2 with slackware 14.1

haziz · 12-08-2014, 10:47 AM

Quote:

Originally Posted by bormant

One large initrd with modules for each kernel version (don't use "-c" option of mkinitrd after first call) or number of separate initrds for each kernel on your choice.

Actually I am not sure I set up the initrd for my generic kernel correctly. Will redo it when I get home. How do I set up an initrd for a kernel different from the running kernel?

cynwulf · 12-08-2014, 11:07 AM

Quote:

Originally Posted by Didier Spaier

You know that stripping down your kernel is usually useless, do you?

Nevertheless, doing useless things is not forbidden by law. So, here is a simple recipe:
[...]
Run "make localmodconfig" in your kernel tree. This is the important step. The new kernel will be modular and the

This will not build a smaller bzImage, just that only modules for the current system will be built - all this achieves is cutting down on (a lot of) build time and bit of disk space. By default the Linux kernel is mostly modules anyway, which means that what is not required does not get loaded.

Still I'd be interested to see the size difference of a kernel built using this method vs Slackware's generic kernel image.

haziz · 12-10-2014, 09:33 AM

Quote:

Originally Posted by Didier Spaier

You know that stripping down your kernel is usually useless, do you?

Nevertheless, doing useless things is not forbidden by law. So, here is a simple recipe:

If not already done, install the -generic kernel shipped with Slackware (of course you'll need to use an initrd for that). Keep the huge one and a lilo stanza for it, just in case.
Boot on your -generic kernel
Plug in (one at a time a few seconds then remove, else you won't have enough USB slots) all the removable devices that you have (USB hard disks, USB sticks, USB cameras, SD cards, whatever), so that all needed kernel modules be loaded. Else you'll loose support for these devices in the new kernel.
Run "zcat /proc/config.gz > <path_to_your_kernel_tree>/.config to copy your currently in use config file in your kernel tree, named .config
Run "make oldconfig" just to make sure you start next step from a clean workable basis.
Run "make localmodconfig" in your kernel tree. This is the important step. The new kernel will be modular and the kernel modules built will be only those currently loaded.
Run "make xconfig" or "make menuconfig" in your kernel tree just to set "Local version -append to kernel release" in the "General Setup" menu. "strip" could be a good "Local version" name. This will allow you to distinguish the new kernel and modules from existing ones.
Compile and install the new kernel and modules as usual.
Make an initrd for your new kernel, with a specific name.
Write a lilo stanza in /etc/lilo.conf for your new kernel, referencing it as well as the new initrd.
Run "lilo -t -v" then if all goes well "lilo".
Cross fingers (this step is optional).
Reboot with your new kernel.

PS there are 13 steps, but only for superstitious people. This is intentional.

Is it possible to use make localmodconfig to compile the modules into the kernel rather than load them dynamically? I seem to have issues with creating a usable initrd, even though I believe I am following the instructions correctly. I realize the kernel will be a bit larger.

Qury · 12-10-2014, 05:28 PM

use localyesconfig

ReaperX7 · 12-10-2014, 07:11 PM

make olddefconfig works well also when going from one kernel version to another. If keeps everything as-is, but auto defaults to the recommended yes|no|modules|internal options where given, or the default values if provided.