RE: u-boot syntax question

bob prohaska <fbsd_at_www.zefox.net> wrote on
Date: Mon, 04 Aug 2025 15:32:09 UTC :

> What's the correct device syntax for u-boot's usbboot command?
> Here's a session transcript:
> 
> U-Boot> usb storage
> Device 0: Vendor: External Rev: 0204 Prod: USB3.0 
> Type: Hard Disk
> Capacity: 953869.7 MB = 931.5 GB (1953525168 x 512)
> U-Boot> usbboot
> ** No device specified **
> U-Boot> run usbboot
> ## Error: "usbboot" not defined
> U-Boot> usbboot 0:1
> ** No device specified **
> U-Boot> usbboot disk0:1
> ** No device specified **
> U-Boot> 
> 
> I've tried 
> starting USB...
> Bus usb@7e980000: USB DWC2
> scanning bus usb@7e980000 for devices... 6 USB Device(s) found
> scanning usb for storage devices... 1 Storage Device(s) found
> Hit any key to stop autoboot: 0 
> U-Boot> usbboot disk0p1
> ** No device specified **
> U-Boot> 
> 
> What's the correct syntax for specifying a usb boot device?
> Or, am I doing something else wrong?


Exploring using an RPi4B context . . .

U-Boot 2025.04 (Jun 07 2025 - 10:14:49 +0000)

DRAM:  947 MiB (effective 7.9 GiB)
RPI 4 Model B (0xd03114)
. . .

U-Boot> help
. . .
boot      - boot default, i.e., run 'bootcmd'
. . .
bootefi   - Boots an EFI payload from memory
. . .
bootflow  - Boot flows
. . .
eficonfig - provide menu-driven UEFI variable maintenance interface
efidebug  - Configure UEFI environment
. . .

U-Boot> printenv bootcmd
bootcmd=bootflow scan

U-Boot> help bootflow
bootflow - Boot flows

Usage:
bootflow scan - boot first available bootflow

U-Boot> help bootefi
bootefi - Boots an EFI payload from memory

Usage:
bootefi <image address>[:<image size>] [<fdt address>]
  - boot EFI payload
bootefi bootmgr [fdt address]
  - load and boot EFI payload based on BootOrder/BootXXXX variables.

    If specified, the device tree located at <fdt address> gets
    exposed as EFI configuration table.


The eficonfig command has options:

Add Boot Option
Edit Boot Option
Change Boot Option
Change Boot Order
Delete Boot Option
Quit

In my context here, Change Boot Order has options:

[*] usb 0
Save
Quit

U-Boot> printenv             
. . .
fdt_addr=4000
. . .
fdtcontroladdr=3ac2b8d0
. . .

U-Boot> bootefi bootmgr

And that boots. Interesting the boot
reports:

Using DTB provided by EFI at 0x39be5000.


I'll note that, in my context, the 2 fdt's
at 4000 and 3ac2b8d0 were in complete
agreement for the captured outputs from

U-Boot> fdt addr 4000
Working FDT set to 4000
U-Boot> fdt print /

vs.:

U-Boot> fdt addr 3ac2b8d0
Working FDT set to 3ac2b8d0
U-Boot> fdt print /

By contrast (via a reboot once the
address was known),

U-Boot> fdt addr 0x39be5000
Working FDT set to 39be5000
U-Boot> fdt print /

had the addition (in "/ {"):

        framebuffer@3e9f1000 {
                format = "a8r8g8b8";
                stride = <0x00000940>;
                height = <0x000001c0>;
                width = <0x00000250>;
                reg = <0x00000000 0x3e9f1000 0x00103000>;
                compatible = "simple-framebuffer";
                status = "okay";
        };

And, in chosen, the addition:

                u-boot,version = "2025.04";

It had rng-seed and kaslr-seed deleted in chosen.

(No other differences.)


The above is rather different than the last time
I explored in a (now old) U-Boot, long ago now.

FreeBSD is using U-Boot's EFI support as far as I
can tell, not directly usb support.


===
Mark Millard
marklmi at yahoo.com