[U-Boot] Edison's U-Boot Architecture

[Zoran Stojsavljevic]

Hello Andy,

Thank you very much for the reply. Instead reply-ing to you in Open Source
fashion, I'll answer to you in the form of the new @. Easier and more
clean/clear approach.

Nevertheless, Edison is cancelled. But since it is already out there, and
you do it, and using it as the test vehicle  Let me start asking in the
Edison/Tangier core design light the similar questions, I already have
asked on this list about U-Boot E3900 and BDW-DX  architectures.

We all know (or I assume U-Boot list knows about Coreboot) and I also
assume majority of the people heard how x86 does work for Coreboot. Quick
recap:
https://www.intel.com/content/www/us/en/intelligent-systems/
intel-firmware-support-package/intel-fsp-overview.html

And we have here in nutshell the following peculiar architecture as the
result of FSP: FSP/Coreboot inter-mingled with U-Boot as a Coreboot's
payload!? Practically three boot-loaders to bring x86 architecture to
YOCTO... FSP being binary blob, actually translating to three binary blobs
in FSP 2.0 spec.

And we know that U-Boot maintainers do not allow binary blobs in U-Boot.
Not like this.

So, what we really want: independent U-Boot on x86, don't we?

I am curious about the following x86 HW/FW configuration with regards to
the U-Boot?

In order to protect INTEL Intellectual Properly (IP), FSP is invented.
Seems that FSP did NOT solve any of the issues. Furthermore, I have no idea
how big projects/players are using x86 with U-Boot (example: BMW, their Ulm
and Munich IT Car depts.) are using YOCTO with x86.

My best guess is that they have private U-Boot (NOT public one), already
adjusted to work as two stage boot-loader, with very clean division of the
layers. Something like this (in the lieu of Tangier, as an example):

Edison/Tangier cores -> IFWI -> MBR -> U-Boot -> eLinux/YOCTO ?!

Here are some explanations regarding the terms/context:

*IFWI is the Intel FirmWare Interface, a binary blob loaded from the eMMC
boot partition that executes a secondary loader (in this case U-Boot) from
the main eMMC. IFWI blobs for the x86 are provided by Intel.*
*Normal IFWI eMMC boot process*

   1. *On-chip boot rom inits eMMC and loads IFWI from the MMC boot
   partitions*
   2. *IFWI looks for OSIP header at top of eMMC (MBR boot block)*
   3. *The header directs IFWI to the start, size, load address, and entry
   of U-Boot in eMMC*
   4. *(need clarification) If u-boot is not found, try the alt u-boot
   image at 5MB into the eMMC*
   5. *U-Boot is loaded into RAM and executed*

*OSIP stands for OS Image Profile, and it is nothing more and less than
INTEL name for very known old fashion MBR, considering DATA structure.*

Andy/Andrej,

Question here: Did I get the correct idea how Edison works with U-Boot?
Could you, please, elaborate how this is done with Edison? (Vopros sdes6:
Ja praviljno ugadal kak eto sdelano/rabotaet? Mozno bolee dannih kad celaja
eta arhitectura rabotaet so Edisonom?)

(I da, esli est6 informacii na Russkom, davaite ih... Rasberus6! Ja boltaju
Russij jazik tocno kak Russkie rozdennie). ;-)

Thank you in advance,
Zoran
_______

On Sun, Oct 8, 2017 at 3:45 PM, Andy Shevchenko <andriy.shevchenko at linux.
intel.com> wrote:

> On Sat, 2017-10-07 at 16:32 +0800, Bin Meng wrote:
>
> +Cc: Ferry (he might be interested in this thread)
>
> > > Edison?! Edison is dead (end), as I know it...
>
> Some people don't think so, there are ones who like the board.
>
> Actually, while working for Linux kernel at Intel I'm using that board
> on almost daily basis to do many tests which are not related strictly to
> Edison or even Tangier.
>
> > >  The project is cancelled.
>
> That's correct [1].
>
> But be honest, don't you like the idea to have an example of the board,
> which was never designed to be ACPI compatible, actually to become one
> (as much as hardware and ACPI specification allow to, of course)?
>
> Besides that I have started looking into Edison's stuff around spring
> time of 2015. You may see my progress here [2] (first article dated
> 27.03.2015, the chapter "6 What is working and what doesn't" shows
> progress of upstreaming). U-Boot was appeared on my radar when the stock
> one stopped working with vanilla kernels.
>
> > > Correct me if I am wrong!
>
> See above.
>
> > I don't know that story. Loop Andy in to comment.
>
> Thanks, Bin, for including me in the loop.
>
> >  But my understanding
> > is that these are pretty much Intel Tangier SoC related,
>
> ...and Merrifield as a platform, which had been used in some x86-based
> phones.
>
> >  and Edison is
> > just a reference board.
>
> Edison is one of the Intel's IoT boards, but the only board from Intel
> MID family [3].
>
> > > Much more important INTEL U-Boot businesses are ATOM E3900/APL-I
> > > family and
> > > CORE-5 BDW-DE (possible also BDW-DE NS),
> > >
> > > What about these?
>
> I can't answer on this. Work on Edison stuff may be considered as my
> hobby project (I have never been a part of an official team which had
> done Edison).
>
> [1]: https://communities.intel.com/docs/DOC-112093
> [2]: https://edison.internet-share.com/wiki/Using_a_vanilla_Linux_kernel
> _with_Intel_Edison
> [3]: https://en.wikipedia.org/wiki/Mobile_Internet_device#Intel_MID_plat
> forms
>
> --
> Andy Shevchenko <andriy.shevchenko at linux.intel.com>
> Intel Finland Oy
>