On 1/2/14, 7:41 AM, "Robert Nelson" <robertcnel...@gmail.com> 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 isn¹t pressed, bootrom loads MLO from eMMC and this loads u-boot from eMMC. I¹m unaware of bootrom loading MLO from SDCard if MLO is missing from eMMC. Do you have a reference for this? Also, I¹m 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: bootcmd=gpio set 53; i2c mw 0x24 1 0x3e; run findfdt; mmc dev 0; if mmc rescan ;then echo micro SD card found;setenv mmcdev 0;else echo No micro SD card found, setting mmcdev to 1;setenv mmcdev 1;fi;setenv bootpart ${mmcdev}:2;mmc dev ${mmcdev}; if mmc rescan; then gpio set 54; echo SD/MMC found on device ${mmcdev};if run loadbootenv; then echo Loaded environment from ${bootenv};run importbootenv;fi;if test -n $uenvcmd; then echo Running uenvcmd ...;run uenvcmd;fi;gpio set 5 5; if run loaduimage; then gpio set 56; run loadfdt;run mmcboot;fi;fi; So mmcdev=0 if the SDCard is installed and mmcdev=1 if the SDCard in missing, so bootpart=0:2 if the SDCard is installed and bootpart=1:2 if the SDCard is missing. If the SDCard is installed, uEnv.txt is loaded from the SDCard, which is where all the customization takes place. What am I missing? Regards, John > >Regards, > >-- >Robert Nelson >http://www.rcn-ee.com/ > >-- >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. >For more options, visit https://groups.google.com/groups/opt_out. -- 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. For more options, visit https://groups.google.com/groups/opt_out.