[U-Boot] Booting Wandboard through USB

[Eric Nelson <eric.nelson@boundarydevices.com>]

On 05/30/2015 10:24 AM, Vincent Stehl? wrote:
> On 05/30/2015 06:49 PM, Tom Rini wrote:
> ..
>> The second would be trying to "fake" things such that for 
>> imx_usb_loader you can pass both SPL and u-boot.img, and SPL is 
>> run, inits memory and just exists and then u-boot.img is loaded
>> and run, similar to how with the non-SPL case you can use the
>> loader to pass in u-boot.imx as well as a kernel, ramdisk, etc,
>> into DDR.
> 
> I wonder if we could use the i.MX6 ROM "plugin"[1] mechanism with u-boot
> SPL, to download it through USB, have it configure the DDR and return to
> the ROM, in a way that would allow us to resume downloading the second
> stage u-boot through USB...
> 
> Best regards,
> 
> V.
> 
> [1] Chapter "8.8 Plugin Image" of the i.MX6D/Q Reference Manual.

;) This is an even older idea:
	http://lists.denx.de/pipermail/u-boot/2012-September/thread.html#134444

In my earlier e-mail, I said that this was more complicated because
it involves hacking the image creation process (and perhaps some
linker scripts).

It also requires that SPL images have some form of flag telling them
not to boot, but return to the ROM boot loader after initializing DDR
(i.e. they need to optionally act like a plugin).

Regards,


Eric