booting and running on raspberry pi from USB

You are using UBOS on a Rasberry Pi. Please state which model you are using, e.g. Zero, Zero W, model 3 or such.
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mike865
Posts: 3
Joined: Fri Jan 05, 2018 7:54 am

booting and running on raspberry pi from USB

Post by mike865 » Mon Jan 15, 2018 3:44 am

first - thanks for putting ubos together, it's great fun. (and got me started on arch)

I have my raspberry pi running off USB with no SD card now, after a tweak or two.

Use an SD card and follow this procedure and your pi hardware will be up-to-date
https://www.raspberrypi.org/documentati ... des/msd.md

afterwards, you can boot other pi3's with this sd card to fix them all for USB.

Ubos doesn't make it when booting off of USB, but with a simple fix it can work.

You have to mount and change /boot/cmdline.txt:

root=/dev/mmcblk0p2 rw rootwait console=ttyAMA0,115200 console=tty1 selinux=0 plymouth.enable=0 smsc95xx.turbo_mode=N dwc_otg.lpm_enable=0 kgdboc=ttyAMA0,115200 elevator=noop

so the boot device becomes:

root=/dev/sda2 rootdelay=30 rw rootwait console=ttyAMA0,115200 console=tty1 selinux=0 plymouth.enable=0 smsc95xx.turbo_mode=N dwc_otg.lpm_enable=0 kgdboc=ttyAMA0,115200 elevator=noop

root= finds the usb device for the second part of the boot instead of the (missing) sd card.

rootdelay= lets the boot complete even when enumerating slower usb devices present


rootwait is ignored, so the delay is needed - however the delay isn't a dumb delay, it's more of
a wait time that will quit early if the device is available.

(see /usr/lib/initcpio/init_functions for details)


I'm unsure, but maybe ubos could be modified so the root= referenecs a PARTUUID or UUID to work on
SD cards and USB drives.


Also, you can add this to the command line to set the mac address:

smsc95xx.macaddr=11:22:33:44:55:66

I assign IP addresses in my network using dhcp keyed from the mac address, so this lets the machine name/ip address follow the USB drive instead of the Pi and it's embedded mac address.

I also use the sandisk extreme cz80 drives - they are bulky but very fast.

:)



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