[Gta04-owner] rationale behind having uImage on the first partition?

Johannes Schauer j.schauer at email.de
Mon Oct 24 15:54:38 CEST 2011


Hi,

On Mon, Oct 24, 2011 at 03:38:05PM +0200, Dr. H. Nikolaus Schaller wrote:
> There is e.g. a big step from 2.6.32 to 2.6.34 for the OMAP processor
> where the console UART is being renamed from /dev/ttyS2 to /dev/ttyO2.
> This must be reflected in the kernel command line.

but this is not uboot - just the commandline uboot gets from somewhere.
in our case: from the boot.scr

> So sometimes, kernel developers change the way boot args are
> interpreted, or add new ones. And then, you have to update them as
> well.

which is even more a reason to have variable boot args possible. if one
can changed the commandline without touching uboot it would make all of
these things much simpler

> >> For touching the commandline there could be a mechanism that makes
> >> uboot load the commandline from a file as it loades boot.scr.
> >> 
> >> This is what qi on the gta01/02 did by loading the append-GTA01/02
> >> files.
> 
> I like this idea!

great!

> Where do they put this file? I think also on the ext2/3 partition in
> /boot?

yes

> How do they read a file into u-boot and then put it into an
> environment variable?

qi is not uboot. it's a standalone bootloader which was written to be
minimal. so qi was made to be never touched after installation but you
could change the /boot/append file and /boot/uImage to your liking as
they were read by qi

> Any pointers how they do it?

no idea how to do it with u-boot yet - but I will investigate as I want
this feature.

> Well, we don't have the capacity to do everything, but we try to
> provide a simple (to use and understand) and rock-solid basic default
> distribution that you can start from (and fall back if your
> modifications don't work). So we will be happy for proposals to
> improve that basic system image.

good - then I will make something work based on the ideas above (kernel
on the second partition with fallback and append file for commandline
options in /boot as well) and then share it here once i get it to work.
If you like it you are welcome to change your setup and if not i will
continue providing this additional option as I like it. :)

> But our goal is not to provide the only and best distribution and
> compete with e.g. SHR, QtMoko, Rowboat/Android, Meego etc.

sure - this approach makes complete sense

cheers, josch


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