[Automated-testing] minnowboard boot & control

[William Mills]

On 02/04/2014 04:57 PM, Nicolas Dechesne wrote:
> On Tue, Feb 4, 2014 at 10:45 PM, William Mills <wmills at ti.com> wrote:
>> 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
>> )
>
> i don't believe Si Boot ROM can boot from TFTP, sounds like a u-boot
> thingy. you probably can boot from USB, though (e.g. fastboot style,
> not HDD style).

Everyone is such doubters :)

Yes TFTP is a feature of AM335x boot rom.  Its in the docs.
I was a bit surprised when I tested it and it actually worked. :)
There are things you can do on the board design that will make it not 
work.  I think the PHYs have to be set to auto-negotate.

The tricky thing is configuring the DHCP server.  The Si ROM uses one
ID and gets told to boot SPL.  SPL uses another ID and is told to boot
u-boot.  The version of dnsmasq I was using at the time could not
handle that and I had to switch to the "real" DHCP server.

If you did have a different AM335x board where TFTP did not work you can 
use Si ROM UART boot mode for recovery.

>
> when you say that you can recover, you assume that you have a good
> bootloader on either SD or eMMC that can be used as recovery?
>

Nope.  The goal is let the SW test trash anything it wants.