Ubuntu doesn't boot from eMMC after flashing

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lusiads
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Ubuntu doesn't boot from eMMC after flashing

Post by lusiads »

I wanted to upgrade from Ubuntu 18.04 to 20.04 so I downloaded the latest Ubuntu image (ubuntu-20.04-5.4-minimal-odroid-xu4-20210112.img.xz) from https://odroid.in/ubuntu_20.04lts/XU3_XU4_MC1_HC1_HC2/. Then I extracted the .xz image and verified the checksum. I flashed the image to an SDcard using W32_ImageWriter. Changed the boot media switch on the XU4 to SDcard and booted into it.
Then, from within the Ubuntu, to flash Ubuntu to the eMMC I ran "dd if=ubuntu.img of=/dev/mmcblk0 bs=4M conv=fsync progress=status". All the commands finished successfully. So far so good. But when I set the XU4 to boot from the eMMC, it refused to boot. There was no output on the screen. The blue LED was blinking but it wasn't like the typical heartbeat blinking. Holding the XU4, I could feel it reboot every few seconds.
The eMMC module wasn't corrupted because I could restore Ubuntu 18.04 from a dd image backup and everything works well again.

Why did the flashed image work on SDcard but not on eMMC? Am I missing something?

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Re: Ubuntu doesn't boot from eMMC after flashing

Post by lusiads »

I read that there are hidden boot blobs on eMMC which aren't accessible to dd. But if I was able to boot Ubuntu 18.04 and dd couldn't alter these boot blobs, I should be able to boot newly flashed Ubuntu 20.04, no?

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Re: Ubuntu doesn't boot from eMMC after flashing

Post by odroid »

Kernel 4.14 or 5.4 needs a newer u-boot.
So you need to update bootloader in the hidden sectors.
Try this update process with a spare SD card.
viewtopic.php?f=53&t=6173
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lusiads (Wed Apr 21, 2021 5:59 pm)

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Re: Ubuntu doesn't boot from eMMC after flashing

Post by lusiads »

I was already on kernel 4.14.141-169 with Ubuntu 18.04.3. Anyway, I did the recovery procedure before flashing Ubuntu 20.04 and it worked. Somehow my blue LED has stopped working and it caused me a lot of headache to figure out what were going on.
Isn't there any other way to update the hidden bootloader without flashing Android. This seems counterproductive to me.

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Re: Ubuntu doesn't boot from eMMC after flashing

Post by odroid »

Try this

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sudo apt install --reinstall uboot
If you have a 1.8Volt USB-UART adapter cable, you can check the boot loader version via raw serial console.
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lusiads (Wed Apr 21, 2021 5:59 pm)

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Re: Ubuntu doesn't boot from eMMC after flashing

Post by lusiads »

This is much better. Thank you.

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