Boot from ssd

[Basher52]

I wanna use an SSD to boot from on my RaspPi 3B+
I installed ArchArm on an SD and that worked but wanna use a lager disk
and since 3B+ is supposed to be able to boot from USB I figured why not
as I have plenty of those.

I did the same thing installing Arch as on the SD card to the SSD but it just
won't work.
I even tried the bootcode.bin thing to an SD but still nothing.

Not even a beep from the green LED (disk activity LED?)

What am I doing wrong?

[clt.r]

Almost same behavior with an nvme ssd, but on rpi5. Just stuck on a boot screen.

[mrtux]

You have to set program_usb_boot_mode=1 in /boot/config.txt first before you can boot from a usb device. I am not certain about the 3B+ however when I was using the Pi 4b, it was most reliable for me to use the SD card with the kernel/device tree, and the operating system on the SSD. Using Uboot, this was easy to accomplish, and then from there, mount your SD card in fstab under /boot. This was faster and more reliable for me while I was using a Pi4.