Re: Upstream linux-omap kernel on Nokia N900?

[Roger Quadros <roger.quadros@nokia.com>]

ext Tony Lindgren wrote:
> * 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.

FYI. kexec-tools will be available in maemo.org repo soon and you can also 
expect kexec patched kernel to be available.

Then we need a kexec helper utility that parses /proc/atags and feeds the 
necessary stuff on Command line for the new kernel.

So the ATAG Hacks will be unnecessary.

cheers,
-roger