[yocto] Using vendo kernel with Yocto

[Paul Eggleton]

On Wednesday 04 April 2012 19:05:05 João Henrique Freitas wrote:
> My vendor device provides a kernel (2.6.22.19) with a patch to its device.
> The device is a arm920t. And the vendor is Mindspeed.
> 
> I want to use Yocto to build the kernel and userland. In the past the
> vendor provided a very old debian-like userland.
> 
> I am trying the following:
> 
> - create a recipe to build the kernel 2.6.22.19 with patch to the device
> supplied by vendor
> - build a image using core-image-minimal only to boot the device
> - I think that linux-libc-headers should be 2.6.22.19, but I am trying with
> linux-libc-headers-yocto
> - the device boots with kernel compiled with Yocto but I have some sort of
> problems with boot scripts. I am investigating.
> 
> Questions:
> 
> With Yocto (1.2M3), I can use a kernel 2.6.22.19 with userland provide by
> Yocto project?
> 
> What is the minimal version of the kernel supported by Yocto?

That's a tough question, I'm not sure many people have experimented to find the 
oldest kernel that will work. 

However, for one of my hobby projects I have been trying to get an iPAQ h2200 
(currently stuck with the 2.6.21-hh kernel) booting with a rootfs produced 
using Poky. The first problem is that the current version of udev that we have, 
164, requires version 2.6.27 or later of the kernel, so you will need to 
provide an older udev. I've been testing with udev 092, but I still hit 
problems on boot - if I disable the initscript that calls "ifup -a" it boots 
successfully, but with it the boot process hangs, even though there are no 
network interfaces other than lo and if I run "ifup -a" after booting then it 
works fine. That was the state a few weeks ago and I haven't done any further 
work on it since then.

I guess what you can take from the above is it's almost certainly possible to 
work with a kernel as old as 2.6.2x, however you will need to downgrade udev 
(most easily by just bringing across udev recipes from OE Classic) and 
possibly other components, and you may still need to do additional 
troubleshooting.

Have you contacted the vendor to see if they can provide an updated patch?

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre