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u-boot how to change default boot mode

100padudle

Hello,

I have a microzed that can boot with the root filesystem on a ramdisk or on an sdcard partition.

I can boot either way by typing 'run sdboot' or 'run sdboot3'.

I noticed the default boot command is set with the u-boot bootcmd parameter.  On my system 'bootcmd-run $modeboot' and 'modeboot=sdboot'.  I would like to change this to 'modeboot=sdboot3' in order to boot with the sd root filesystem.

I type

zynq-uboot> setenv modeboot sdboot3
zynq-uboot> printenv modeboot
modeboot=sdboot3
zynq-uboot> saveenv
Saving Environment to SPI Flash...
SF: Detected S25FL129P_64K with page size 64 KiB, total 16 MiB
Erasing SPI flash...SF: Successfully erased 131072 bytes @ 0xe0000
Writing to SPI flash...SF: program success 131072 bytes @ 0xe0000
done
zynq-uboot>

but as soon as I reset the board I get the original modeboot value.

zynq-uboot> printenv modeboot
modeboot=sdboot


What is going on here?  Isn't the purpose of modeboot to allow easy boot mode changes?  What am I missing?

    Pete

  • 0

    Hi Pete,

    The modeboot environment variable is a special variable that gets set by U-Boot based upon the settings read from the Zynq boot mode register.  Based upon the bootmode jumper settings for your board, that modeboot variable should get updated each time the board is powered up.

    Have you tried, 'bootcmd=run $sdboot3' instead?  That should work the way you expect it to.

    Regards,

    -Kevin