[meta-intel] Installing a Yocto image to emmc

[Trevor Woerner]

On Fri 2017-03-17 @ 11:19:30 PM, Duran, Randy G wrote:
> Hello, I am trying to get information on software or procedure to flash
> a Yocto image on to a Joule's emmc not using normal steps such using a
> bootlable USB nor sdcard. I am attempting to automate flashing an image
> on to device without any human interventions. I am looking for something
> like Platform/Phone flash tool software equivalent for android devices. Any
> information is appreciated.

Flashing to a board's eMMC instantly puts you into "vendor-specific" country.
Each vendor/board will have its own way of doing it, usually involving vendor
specific software/protocols. If you're lucky the vendor will have implemented
android's fastboot, which makes it more or less non-vendor-specific, unless,
of course, they don't really implement it properly... ;-)

Newer versions of u-boot have fastboot support, so, if enabled, you can
sometimes flash via u-boot.

The toughest part about flashing to eMMC is the procedure required to put the
board into the mode to accept flashing to its eMMC.

The dragonboard, for example, requires you to hold down the "volume down"
button while rebooting, then you can use fastboot. Do you have an easy way to
automate holding down the volume down button while rebooting?

The firefly requires you to hold down the RECOVERY button while pressing the
RESET button. Or you can just use "dd" from within Linux to zero the first
couple sectors of /dev/mmcblk2, then reboot. The protocol to flash its eMMC is
something they came up with, but I think they recently released that code (I
haven't looked at it yet).

It's been a while since I've used a BBB but the last time I checked, one would
create an image using OE and in that image would be an eMMC payload. Once
booting into Linux you'd then write the payload to the eMMC. Not sure if
there's a way to do it "offline".

So if you're working with the Joule, you'll have to find its way of flashing
its eMMC. Hopefully you know someone who works at Intel who can help with the
specifics... ;-)