Hi all,
On 05/30/2015 11:09 PM, Eric Nelson wrote:
On 05/30/2015 10:24 AM, Vincent Stehlé 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).
According to the RM, the plugin image is expected to load the actual
boot image in memory and report the start/len/ivt parameters to the
boot ROM. Then I see 2 problems:
1. It seems that at this exact point if the plugin returned "success"
the boot ROM will start executing the downloaded image and there's no
intent to download anything else from USB.
2. Even if there was a way for the boot ROM to download more data, the
previous communication sequence ends with "jump header" (in imx-usb-
loader jargon) which means we can't differentiate between boot ROM
returning for more boot data, and a fresh new boot session.
Regards,
Nikolay
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