I'm surprised this post even came through. The beagleboard forum /moved/ to a new web-based-only system (which I have refused to fight with -- I tried but found it cryptic and unusable for someone accustomed to newsreader clients which fetch all messages in a batch and permit later responses to be made; I abhor web-based "fetch one message, make a reply, send, fetch next message")
The Google Groups forum has been abandoned. On Wed, 1 Sep 2021 16:50:11 +0100, in gmane.comp.hardware.beagleboard.user Chris Green <cl-rxdkphot...@public.gmane.org> wrote: >If one has a BBB which normally boots from eMMC is it possible to >write a script that will reboot from the microSD card? > On current Beagle systems, it is u-Boot which determines the boot device dynamically. That is: By default the u-Boot in the eMMC starts processing It then scans for a bootable uSD card If a valid uSD card is found, it toggles the boot device to be the uSD card, and proceeds to load the configuration from the uSD card; otherwise it continues to load the configuration from the eMMC If there is no u-Boot (and maybe other files) found on the eMMC, the SoC [hardware] boot sequence is to look for a valid uSD card and load u-Boot from that card. The end state: if a bootable uSD card exists, it automatically becomes the booted image, skipping the rest of the eMMC (u-Boot comes from the first version found: eMMC then uSD). Prior to this form of u-Boot, one was required to hold down the boot-select button on the BBB to force uSD card load. But that form of u-Boot vanished near the end of the Wheezy era (Debian 7). This was also the days of kernel loaded device tree overlays -- u-Boot loaded overlays came in during the Jessie (Debian 8) era. The two u-Boots are totally INCOMPATIBLE with Debian versions of the other style (Wheezy u-Boot does not load DTOs, but Jessie and later Debian kernels expect to find the DTOs already loaded). I don't know enough about u-Boot and uEnv.txt to know if there is some way to modify uEnv.txt to /not/ transfer control to the uSD card except when you want to do you back-up stuff. -- Dennis L Bieber -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/i2cvigt822989kf4gbfu2ob6a5p62osu6v%404ax.com.