Re: Pi2 bootcode.bin puzzle

druck <news@druck.org.uk> wrote:

On 27/03/2025 15:53, Theo wrote:

druck <news@druck.org.uk> wrote:

It may still work on the Pi 2B, but being slower you may need to
increase the value of rootwait in cmdline.txt - particularly if it is a
spinning disc rather than an SSD - it could take 60 seconds before the
drive is readable.

 
I think the problem here is that start.elf, config.txt, the kernel and
cmdline.txt are all on the USB device - you can't put a timeout in
cmdline.txt because by that point you already need the USB device up to read
that file.
 
The alternative approach would be to have a regular bootcode.bin, start.elf,
kernel, etc on the SD card and then tell the kernel to find its rootfs on a
USB drive, at which point rootwait may help.  (I think Bob is using FreeBSD
but there is probably an equivalent option there).  Or to interpose u-boot
for the 'kernel' on the SD card, and then tell u-boot to find the kernel on
USB.

 
That's the only way it works on older devices.

Supposedly you can make them USB boot by just providing a bootcode.bin on
SD, then they pick up start.elf, config.txt etc from USB.  I've not tried
this, but it appears to work for some people.

(previously bootcode.bin didn't know anything about USB, but since Pi 3/4/5
can USB boot I believe that code has now made itself into bootcode.bin)

Theo