Re: RPi4 - Booting from mSD with USB storage

> On 3 Jul 2021, at 17:14, Mark Millard <marklmi@yahoo.com> wrote:
> 
> You do not report what, if any, error messages U-Boot is
> reporting.
> 
> Just in case it is relevant, I', going to quote a list
> message from back in April:
> 
> QUOTE
> I will note that one thing that was discovered was
> that u-boot does not well support having a USB device
> with more than one storage LUN in the device. It
> produces messages like:
> 
> Scanning disk usb_mass_storage.lun1...
> ** Unrecognized filesystem type **
> ** Unrecognized filesystem type **
> Scanning disk usb_mass_storage.lun3...
> ERROR: failure to add disk device usb_mass_storage.lun3, r = 20
> Error: Cannot initialize UEFI sub-system, r = 20
> 2676208 bytes read in 41 ms (62.2 MiB/s)
> libfdt fdt_check_header(): FDT_ERR_BADMAGIC
> Error: Cannot initialize UEFI sub-system, r = 20
> EFI LOAD FAILED: continuing...
> BOOTP broadcast 1
> DHCP client bound to address 192.168.1.171 (121 ms)
> *** ERROR: `serverip' not set
> 
> (Text is actually from a test that Fedora's configuration
> at the time was getting the same sort of problem from its
> u-boot build. The text just happened to be handy to grab.)
> 
> It seemed that such a device needed to be plugged in after
> u-boot was no longer involved (and to be unplugged before
> u-boot would again be involved).
> 
> I mention this because having multiple SATA drives possible
> might be an example of multiple storage LUNs for a single
> USB device. There is:
> 
> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253983
> 
> that starts before the u-boot tie was known and progresses
> through it being discovered --and that mistakenly indicates
> "Closed FIXED" to indicate that it was not a FreeBSD
> problem. (No problem was "fixed": just isolated to not
> be FreeBSD's problem.)
> END QUOTE
> 
> To my knowledge, you would have to adjust U-Boot's
> configuration to complete ignore USB in order to
> work around U-Boot's problem for such contexts.
> Looks like Robert Crowston provided some notes
> that go in this driection.
> 
> There might be multi-storage-device (each single
> LUN) that also have problems, for all I know.
> 
> ===
> Mark Millard
> marklmi at yahoo.com
> ( dsl-only.net went
> away in early 2018-Mar)

I think you’ve hit the nail on the head. It’s a 2 SATA drive USB enclosure and I see errors just like this.

> On 3 Jul 2021, at 14:41, Robert Crowston <crowston@protonmail.com> wrote:
> 
> You could create a boot script ("u-boot.scr") and place it in the root of your sd card alongside u-boot. U-boot will interpret it at start up. You can use that to modify the "boot_targets" variable such that it doesn’t scan for usb drives, or so that it tries to load from mmc first.
> 
> As I recall part of the problem is there are several mmc-like devices on the pi4 and the one we want is the third one (mmc2). That’s quite low in the boot priority order.
> 
> First you should become a little familiar with what u-boot is doing when it probes your devices. I’d suggest plugging in a keyboard (or a serial console) and interrupting the automatic boot. Once you know how to make it boot from mmc, you can encode that in a script. 
> 
> u-boot.scr is a compiled file, so you need the “mkimage” tool from u-boot. 
> 
> I’m not sure if this is the best way, perhaps I am overcomplicating it. Good luck.
> 
>     — RHC.

Thank you for the pointer, I’ll look into this, it sounds promising.