[maemo-developers] [maemo-developers] Kernel compilation on Nokia 770

[From: Johannes Eickhold]

On Thu, 2006-03-09 at 19:40 +0200, Andrey Khurri wrote:

Hi Andrey,

> I need to compile certain version of kernel with some patches on my
> Nokia 770. Let's say version 2.6.13.1
> I had a look at "HowTo KernelCompilation" on maemo.org. It uses
> scratchbox for that. I've got already scratchbox environment working.
> What is not obvious to me is how to use this algorithm in my case.
> Should I add an entry to /etc/apt/sources.list which would link to a
> repository with the needed kernel version? In the given example the
> kernel source they fetch is "kernel-source-2.6.12.3-osso22.tar.gz" I
> am not sure whether this is kind of specific kernel source for Nokia
> 770.

I think it is, because e.g. the source for the needed wlan module is
included in that package.

> If so where I can get the same but for higher version (2.6.13.1)?

Good question. I suppose it should be supplied by Nokia in the maemo
repo. Why do you need a newer kernel version?

> As well as this the content and intention of packages "kernel-package
> 8.083.tar.gz" and "su-18 kernel package"  are not clear to me.

As far as I understand it, the su-18-kernel package is provided to
enable developers to install this package into their scratchbox and
after that flash it on the device. See the package desciption:

~ > apt-cache show su-18-kernel
Package: su-18-kernel
Priority: optional
Section: utils
Installed-Size: 1496
Maintainer: Ed Bartosh <eduard.bartosh...>
Architecture: all
Version: 2.6.12.3-200550osso1
Provides: su-18-kernel
Filename:
pool//maemo1.1/free/s/su-18-kernel/su-18-kernel_2.6.12.3-200550osso1_all.deb
Size: 1474108
MD5sum: c402beb5c79e798b4620b73004ae5243
Description: Flashable Linux kernel for SU-18 hardware
 This package provides a flashable kernel image for Nokia 770.
scratchbox-architecture: uarm

If you rebuild this package as the kernel HowTo suggests, you get
manageable (i.e. in package form) modified versions of your kernel and
kernel-headers package.

> I guess it is also feasible to put all the sources to Tablet and start
> compilation process there in usual way. But in that case it would be
> much slower and the memory size needs to be tremendous. Am I wrong?

Yes and no :). It would be a bad idea to compile the kernel on the
device due to the limited resources there. IMO it is better to follow
the HowTo. To be honest, I have done it in a slightly different way
because I didn't wanted to setup another scratchbox target (it would
have been the 3rd) because I have limited space on the / partition of my
development system. The steps were the following:

1. installed the gcc-3.4 toolchain in the host debian
2. installed the su-18-kernel, kernel-source-2.6.12.3 and kernel-package
packages inside my existing ARM target in scratchbox (HowTo steps
"Compilation 1-5")
3. compiled the kernel source from outside scratchbox using the compiler
from the gcc-3.4 toolchain with the usual make menuconfig, make zImage
commands.
4. flashed the new zImage binary onto the device

That means I haven't rebuild the package which I don't need anyway. I
haven't copied the module binaries onto the device! Only needed the
changes in the kernel image itself. It seems the new kernel is working
with the old modules.

Greets, Jonek.