DONT INSTALL TO EMMC R77-12371.7.104.g78f88d6 VERSION YET!

[tophneal]

If you dd zeros like that, you should be fine.
Alternatively, you can dd the newest uboot version of Manjaro/Debian/... onto the right offsets, and you will be fine as well.
You can find more details and example commands here: https://forum.pine64.org/showthread.php?tid=9062

It might be better to use mrfixit's 2.0 uboot, or pcm720's. From what I've seen lately, mainline uboot does not want to boot imgs that are using BSP kernels. Though, it could've been fixed and I missed it.

@shoichimiyake  if you want to continue using CrOS from your emmc here are 2 good, updated BSP uboot options:

https://github.com/pcm720/rockchip-u-boot/releases
https://github.com/mrfixit2001/updates_r...filesystem

In the second link, there is a script you can download with the uboot files and run within a shell in crosh. There is also this script from Arglebargle that's a bit more simplified:
https://pastebin.com/raw/EeK074XB

Dear @tophneal, thank you so much!

The link you mentioned looks good, very  clear for me what to do. I'm going to refer the link.
I just tried some OSes just for interest, and my preference is NetBSD to use with PBP, but thanks for your suggestions!

But I'm in trouble with PBP by occasional suspend issue after I recovered my eMMC with Manjaro image.
I was carefull to open my PBP, but while I was re-flashing my eMMC, unexpected suspend issue happened and bothers me.
suddenly screen black-out, power LED (green) turns off, stay suspended until I push [POWER] key on the right-top.

When I booted NetBSD from SDCard, ther kernel message 'lid on" and "lid off" displayed randomly.
So I have to struggle with this issue before using PBP stable...

But it's a topic of off-thread, I should go another thread.

thanks!
shoichi

It sounds like your netbsd install maybe trying to do s3 sleep without a bsp uboot. However, you’re right, it’s probably be better to post as a new thread in the netbsd forum.