M1dn1ghtN1nj4 wrote: ↑
Sat Jan 05, 2019 6:16 pm
While I've been a PC tech for pretty much my whole life, there are aspects of certain components I still have trouble with. After reading this through, at least 3 times, it sounds like you can't actually change the boot "order". So in order to actually boot off of a USB drive on my Pi (not using USB host booting), I'd still have to remove the sdcard from the system.
Nope, that's not correct. While you can't truly change the boot order, you can tell it to boot from either USB or SD, regardless of card state.
If you use the GPIO option you can control the boot device with a switch. Once that option is set the Pi will check the GPIO and boot from either SD or USB, depending on what it finds on certain GPIO pins. By pulling the relevant pins high or low you tell the Pi which to boot from.
In simple terms, flip a switch one way and it boots from SD card. Flip it the other way and it boots from USB.
The down side is that some of the GPIO is used, which may complicate the use of some HATs or other GPIO projects.
The relevant section is this:
The GPIO boot mode OTP bits can be programmed by adding program_gpio_bootmode=n to config.txt, where n is 1 to select the low bank (22-26) or 2 to select the high bank (39-43). Once added, boot the device, then power-cycle it (rebooting is not sufficient). You should expect it to no longer boot (all boot modes will be disabled by default). Apply a pull-up to the required pin to enable the required boot mode. After programming, the config.txt setting can be removed.
Note that this is a permanent change that cannot be undone once it has been enabled. That means your Pi3B/3B+ will always need a pull-up on the GPIO to boot (without it the Pi will not boot at all). Also be careful not to set the wrong GPIO range, as that could brick your Pi. I believe the correct range is low for the consumer Pi3B/3B+, but double-check that before programming the OTP bit (other range is only for CM).
My mind is like a browser. 27 tabs are open, 9 aren't responding,
lots of pop-ups...and where is that annoying music coming from?