On Thu, Jan 02, 2014 at 01:56:22PM -0800, John Syne wrote: > > On 1/2/14, 7:41 AM, "Robert Nelson" <[email protected]> wrote: > > >> Hi, > >> Thank you for that clarification. > >> Does the boot modes (if altered) survive if the power is removed and > >> reapplied? > > > >Well they go back to factory default.. > > > >This is why every "flashing" guide says pull the power.. As weird > >things happen when you "soft" reboot after flashing the eMMC... > > > >> The uEnv.txt is located in the boot partition, on both eMMC and uSD > >>card. > >> What line specifies in wich order to boot? > > > >In most cases it's more then just "one" line.. > > > >> > >> I was wondering why the default is to first try eMMC even when an uSD > >>card > >> is detected. > > > >Because you are over thinking it. The bootrom is "simple" and it is > >setup to read the eMMC first. > > > >Here's the boot order: > > > >bootrom loads MLO from eMMC (if that fails it moves to microSD (hence > >dd if=/dev/zero to eMMC makes booting from microSD work..) > >MLO loads u-boot.img from eMMC > >u-boot.img first looks at microSD for uEnv.txt, reads that file in. > Hey Robert, > > Now you have confused me and I thought I understood how the boot process > worked. > > If the boot button isnıt pressed, bootrom loads MLO from eMMC and this > loads u-boot from eMMC. Iım unaware of bootrom loading MLO from SDCard if > MLO is missing from eMMC. Do you have a reference for this? Also, Iım > unaware of MLO loading u-boot from SDCard if u-boot is missing from eMMC. > Do you have a reference for this? The only option to load from SDCard if > it exists is in the u-boot environment bootcmd which is here:
Section 5.3.5 (Boot Modes) of the Beaglebone Black SRM documents this behavior. It's a feature of the ROM bootloader peripheral search order. -Matt -- 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]. For more options, visit https://groups.google.com/groups/opt_out.
