On Sat, Apr 3, 2021 at 8:40 AM Dennis Lee Bieber <[email protected]> wrote: > > On Fri, 2 Apr 2021 14:36:51 -0600, in gmane.comp.hardware.beagleboard.user > John Allwine <john-/83Ax2S01hhWk0Htik3J/[email protected]> wrote: > > >That said I still don't fully understand the problem. Where is U-boot > >stored? I'm booting from a microSD card and using that card in one board > >works, but didn't when I switched to this other board. Does it not pull > >that data from the microSD card? Is it reading from the eMMC of the other > >board? > > As I understand the process... Unless the boot-select button is held > down, recent images (mid-Jessie time-frame I believe) contain a u-Boot that > checks for the uSD card. So... > > Without boot-select, the u-Boot on the eMMC is loaded. It then checks > for the presence of the uSD card, and then for a bootable system on that > card. If such is found, the uSD card is made primary and booting > /continues/ using the files found on the card. u-Boot is still the version > from the eMMC. > > With the boot-select, the eMMC is completely bypassed and the uSD card > is made primary, and u-Boot searched for on the uSD card. If found, it is > loaded and continues booting using the uSD card. > > I'm not certain of when the "u-Boot loads device tree" vs "kernel > loads > device tree" change took place. If it was after the auto-uSD card boot > change, one has the potential to have an eMMC u-Boot that expects the > kernel to load device tree, while the kernel on the uSD expected u-Boot to > load them (or if the uSD card is old enough, an eMMC u-Boot that does load > device trees, running a kernel that expects to read the device tree files). > > Periodic flashing of the eMMC with current images is probably > recommended, just to ensure the u-Boot image is up-to-date (and cleaning > out crud that might have accumulated on the eMMC <G> )
It does come up on the list often that an old u-boot on the eMMC can cause problems even when using the latest image on micro SD. If people just want to run from microSD, then Robert normally recommends people delete u-boot on the eMMC: sudo dd if=/dev/zero of=/dev/mmcblk1 count=1 seek=1 bs=128k regards, drew -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAEf4M_AWLf%2B2%2BxcDwcr%2BbwwSE5mFJjW29%2BrOUXBv%2BYtmh2d38A%40mail.gmail.com.
