[fedora-arm] Fedora ARM VFAD - Help test Fedora 18 ARM TC1, kernels and device tree! - 2012-10-15

[Jon]

On Tue, Oct 16, 2012 at 6:25 AM, Peter Robinson <pbrobinson at gmail.com> wrote:
>> Made good progress today. :)
>> Was able to get Device Tree to work on both Panda ES and Trimslice.
>
> Awesome!
>
>> What works: appended DTB kernels. (cat the .dtb to the end of the
>> zimage, then generate a new uImage)
>>
>> What does NOT work: loading the .dtb from u-boot (similar to the initrd)
>
> It's a good start.
>
>> One notable breakthrough was being able to boot the trimslice with the
>> latest version of u-boot.
>> (had to change boot.cmd to have root=/dev/mmcblk0p3)
>
> OK, interesting to see why labels don't work.
>
>> For the panda it would seem not all the parts of omap kernel are moved
>> over to DT, some things do not work.
>
> Not surprised as I believe 3.7 should be the end of the OMAP DT
> support additions but it's good to know it actually works which is my
> primary concern so that we know it has all the bits needed in F-18.
>
> Peter

A few things to discuss:

* update u-boot in f18 to 2012-10 (important for panda)
 -> Apparently we only bundle u-boot with omap anyways.
 -> The updated version only appears for f19, this would be a "nice to
have" type thing for f18.
 -> Only the updated version loads the .dtb succesfully from u-boot,
otherwise we can append the .dtb in 2012-07.

* Do we even want to load the .dtb for panda?
 -> my experience was not happy, the omap4-panda.dtb makes things break.
 -> Breaks: WiFi, Display Subsystem and maybe USB-Host functionality.
 -> I do believe the omap folks are busy working on improving DT, so
maybe we can wait?

* Trimslice
 -> was able to get mmc/sdcard booting with the latest DT-enabled u-boot.
 -> unfortunately when Brendan ran into a snag when reproducing with
his internal /dev/sda boot.
 -> on the trimslice the .dtb seems to have to be appended, so far
loading via u-boot is not happy.
 -> also there is a rumor that trimslice might support a uEnv.txt type
thing, would be nice to have.

* adding the .dtb's to the distro.
 -> I hear the .dtb files are somehow generated from the kernel sources?
 -> sometimes we may have to append them to the kernel zimage (trimslice).
 -> Other times they get loaded via u-boot (Panda).
 -> Would be interesting to findout how our image generation process
deals with this.
 -> necessary first step is deciding how we get access to the .dtbs
from the distro.


-- 

-Jon