Re: Upstream linux-omap kernel on Nokia N900?

[Tony Lindgren <tony@atomide.com>]

* Roger Quadros <roger.quadros@nokia.com> [100419 05:06]:
> Balbi Felipe (Nokia-D/Helsinki) wrote:
> >Hi,
> >
> >On Mon, Apr 19, 2010 at 01:49:15PM +0200, ext Arnaud Ebalard wrote:
> >>Nokia N900 is shipped to users with a 2.6.28 omap kernel. Many patches
> >>for the hardware and various features have been pushed upstream by Nokia
> >>developers and possibly others. Those are now available in current l-o
> >>tree.
> >>
> >>Nonetheless, many drivers and various features are still missing
> >>upstream. Simply put, one cannot expect to run a current l-o kernel on
> >>the device (and expect to get a GUI and/or make call with the device).
> >
> >tell me about it :-p
> >
> >Thing is that it doesn't really depend only on Nokia to get those
> >parts done. Well, we can get the kernel part done by just cleaning
> >up and porting the 2.6.28 drivers to current mainline, but in case
> >of e.g. SGX we still miss the xorg driver and I don't think
> >that'll be released any time soon.
> >
> >Another problem is that the bootloader believes it can pass all
> >the obsoleted OMAP TAGs to kernel and the 2.6.28 kernel depends on
> >those, maybe that can be worked around. I don't know whether
> >kernel simply drops invalid TAGs or not...
> 
> Yes kernel simply drops unrecognized TAGs and just prints a warning message.

All the the custom tags should be replaced with platform_data.

If something is needed for revision detection of the board,
there is arm-linux common ATAG_REVISION.

However, also Maemo userspace depends on some things set by the
custom tags. As this is non-standard, we should not spend much
effort on that. Instead we should concentrate on making N900
work with any distro the standard Linux way.

So I recommend using kexec patched Maemo kernel, then boot the
new mainline kernel from Maemo kernel and mount root directly
on the eMMC.

As Maemo user space has some dependencies to the partition
layout, you need to keep the existing partition layout too.
In any case, I ended up resizing the eMMC partitions and using
/dev/mmcblk0p2 (mounted as /home in Maemo) as the new root
partition.

Cheers,

Tony