[fedora-arm] F-18 trimslice images are DOA

[Hans de Goede]

Hi,

I know a lot has already been said and written about the
transition to DTB and the trimslice. Still I must say
I'm disappointed in our trimslice story for F-18.

I've had a trimslice sitting in its box for ages now,
and as I wanted to work on bug 893157, it was time
to finally unbox it and install Fedora on it.

So I downloaded the F-18 image, xzcat-ed it to a sata
disk (I've the trimslice-h with internal 2.5" sata bay),
updated boot.scr to the usb one and booted the trimslice.

And it failed, and now 2.5 hours later, I finally have
things working with the original shipped 3.6 kernel,
and I yet have to tree 3.7 or 3.8.

Let me repeat this, it took *me*, 2.5 hours, to get
the basic images to boot! And I've build Allwinner
A10 kernels + uboot from source, including writing my
own .cmd files for them, etc. IOW I know this stuff!

So TL;DR. our F-18 trimslice images suck. And TBH for
no good reasons, we could have done better and we
should have done better. This is going to cost us
users <full stop>.

So enough ranting on this, what happened in my case:

1) As said I followed the wiki instructions for
installation to a usb-mass-storage device to the letter.

2) This did not boot, serial console showed that the problem
was that dtbs/tegra20-trimslice.dtb was missing.

Sorry, have to rant again here, say what? our GOLD images
have a .cmd file referring to a file which is not there?
WTF, did we do QA, any QA at all on this, how can this
have slipped through ???????   ?????    ??????

3) As I know this stuff, the solution *seemed* easy,
remove the command to load the dtb (not strictly necessary)
and the 3th parameter from the cmd file, mkimage the
scr file, done. After all the 3.6 kernel does not require
a dtb, right ?

4) Hmm, now the boot hangs after the usb probing is done,
weird. Lets try an sd-card

5) Same experience, ah it is hanging in waitroot, so why
is it not finding root

6) Ah, root is specified by UUID, if I add root=/dev/mmcblk0p3
then it does work.

7) And with the usb boot it does not see the usb-disk at all ->
no usb-storage driver -> no initrd (so no root by UUID).

8) But why no initrd? It is being loaded and the second parameter
to bootm is correct ???

9) Try 3 different trimslice firmware versions -> no go.

10) Lets redo from start lets simply drop in the
missing dtbs/tegra20-trimslice.dtb file, even though no dtb is
needed for a 3.6 kernel, as the successfull boot without it in
step 6 has proven. But lets try anyway combined with the original
boot.cmd.usb file + dtb capable firmware

Heuh, now it does see the initrd, and everything works ... ????

So we need to pass-in a dtb for the initrd to work ????

###

So is this all a bit mysterious yes, still could we've done better?
yes!

I had already updated to the dtb capable firmware before I begun,
so if the dtbs/tegra20-trimslice.dtb file would have been
in the image as it should have been, everything would have worked
in one go.

That would have helped me, but not users who have not updated
the firmware. The wiki-page says that the firmware update is
needed when you do a kernel update, IOW it implies that the GA
images will work with old firmware, which they don't, since the
initrd seems to not get loaded, which breaks even mmc booting,
because we specify root by UUID which requires an initrd.

###

So how to move forward with this. We should update the wiki
with clear and precise step by step instructions on how to make
things work, or maybe even just respin the images!

Assuming we're going with the wiki instructions, for sdcard
users we've 2 options:
1) Treat them the same as usb-disk users, see below
2) Provide an updated boot.cmd.mmc0 and boot.scr.mmc0 for them,
which removes the use of the dtb, and specifies root as
root=/dev/mmcblk0p3. Idem with mmc1 for micro-sd users (needs
to be tested).

For usb users we need the initrd, which for some reason is
not working when not loading the dtb ??? And loading the
dtb means new firmware. So we need to add instructions for
usb-disk users to *first* upgrade the firmware, and also
to add the missing dtb file to the image before trying
to boot it.

Regards,

Hans