[Automated-testing] minnowboard boot & control

[William Mills]

Dave/Scott/All,

I am trying to understand the Minnowboard boot flow and how it can be 
controlled from a test bed.

On BeagleBone Black:
The Si Boot ROM can boot from TFTP.
The Si Boot ROM can boot from eMMC or SD.
With relay controlled pull-ups/downs I can control the boot device.

With this control I can recover a device regardless of what a previous 
test has done to eMMC or SD Card.
(My work is documented at:
http://processors.wiki.ti.com/index.php/BeagleBone_in_a_Board_Farm
)

My assumptions & questions about Minnow and it's UEFI:
A1) always boots from SPI
Q1) Does SPI have a write protect jumper or other means to protect SPI
contents via external control (e.g. relay)
A2) SPI contains UEFI
Q2) Does SPI contain all of UEFI?  Does it have the Shell?
     Are there important components that always come from
     the UEFI boot partition?
Q3) Does UEFI look at any pins or buttons to effect boot order
Q4) Does UEFI support user configuration of boot order?
     is that preference stored in SPI?
Q5) Does UEFI support boot from network?

At a minimum I think we can:
* Interrupt boot via serial control and change boot order
* Assume no one trashes SPI in the general case
* Possibly rig & automate SPI flasher tool to recover board for test 
beds that require extra robustness

So far I have read:
http://elinux.org/Minnowboard:SPI_Boot_flash
http://www.elinux.org/Minnowboard:Booting_Angstrom
http://elinux.org/Minnowboard:Debian_Bare_Minimum_Bootstrapping
http://www.minnowboard.org/technical-features/
Minnow Board UEFI 1.0 release
	Release Notes  **
	doc/dediprog ...
	doc/serial console ...
	doc/flash utility

** After reading the release notes I still do not understand:
- if network boot is or is not working.  It is in the fixed and known 
issue lists.  It is not in the "fixed" boot order anywhere.
- It appears that once you boot from SD or USB, there is no option to 
interrupt to get a shell if that SD or USB image no longer works.
Is that correct?

I do have a Minnowboard at home but I hate to admit it is still in the
box.  I did look at it and I think I booted it once but was being
"disciplined" and did not study at that time.  I have yet to pick it up
again.  I'll rectify that soon.

Bill

---------------------------------------
William A. Mills
Chief Technologist, Open Solutions, SDO
Texas Instruments, Inc.
20450 Century Blvd
Germantown MD 20878
240-643-0836