Re: Troubles booting Pi2 from USB using bootcode.bin method

On 2021-Oct-27, at 09:28, bob prohaska <[email protected]> wrote:

> On Sun, Oct 24, 2021 at 08:43:32PM -0700, bob prohaska wrote:
>> I've got an early Pi2B (not plus) that has been booting reliably
>> from a USB2 disk connected via a USB3 hub using just bootcode.bin
>> and timeout on the DOS partition of the microSD card.
>> 
> It turns out the USB3 disk boots normally _provided_ the old
> USB2 disk remains connected. I didn't try that initially both
> because I didn't need both disks and because the boot order 
> couldn't be obviously controlled. 
> 
> It turns out the new disk is discovered first and boots as 
> desired, so the system is busy building an up-to-date world
> and kernel. There's room for a ports tree on this disk.
> 
> Does the ports version of u-boot include support for the
> bootcode.bin-only mode of USB booting?

Before U-Boot is involved there are other files involved
such as a start* file from the USB device. With appropriate
config.txt content, and possibly other settings, the boot
is likely rather explicit about its early activity. (But I
do not currently have access to a RPi2B v1.1 or earlier to
test the details on. In fact, the accessible only RPi*'s
are RPi4B 8 GiByte ones.)

(I wondered if you meant RPi3B: To my knowledge there is
no such thing as a RPi2B+ so the "plus" reference suggests
an early RPi3B might have been what was involved.)

> Right now I'm using
> the version of bootcode.bin offered at 
> https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#special-bootcode-bin-only-boot-mode
> 
> Without having the USB2 disk connected the serial console hangs
> with what looks like "cb" as the only output. It's unclear if
> u-boot is starting at all. The red and green LEDs remain lit,
> seemingly indefinitely. 
> 
> 


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)