Does Jupiter’s U-Boot support loading extlinux? I want to customize the kernel boot parameters and rebuild a customized kernel, so having the boot menu (over the serial console) is really needed.
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IDK if this is what you’re looking for, but the env partition (mmcblk0p2) is pretty much text. I’ve replaced the null bytes with newlines for easier reading, and it seems to have a line with bootargs. I haven’t tried changing anything in there yet, but I would assume you can just adjust the bootargs that way. But yeah, extlinux support would be so much better…
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Did someone manage to customise boot settings in u-boot for the Jupiter board?
I just realised what you described about env partition (mmcblk0p2 ) and I updated the bootdelay setting from 0 to 5 to be able to stop u-boot from auto booting but what I got was a warning during boot about the environment having an unexpected checksum CRC and proceeded to use the default environment (that must be something hard-coded in u-boot at build time) and completed the boot process again with a bootdelay value of 0 so I didn’t have a chance to stop the autoboot.
Is there a way to customise u-boot environment for this board without having to build everything from scratch (is this documented somewhere)? What I’d like to do is to be able to use u-boot interactively on this board to boot my own code and/or test other OS supporting riscv64 hardware.
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I also downloaded fw_printenv tool and tried to run it in Bianbu Linux and pointed that tool to a copy of the environment blob that is stored in mmcblk0p2 but couldn’t get it to print the environment, so no point to try to change settings values with fw_setenv anyway.
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In order to stop the autoboot, I ended renaming the kernel file name in the SD card.
It’s certainly not ideal but that for sure will stop autoboot and then you can inspect the u-boot environment and options to load your own code, manually load Bianbu Linux or any other OS.
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for messing with uboot environment file/ partition there’s mkenvimage command originating from one of u-boot packages, namely
ii u-boot-tools 2024.01+dfsg-5ubuntu2 riscv64 companion tools for Das U-Boot bootloader
unexpected checksum CRC
yeah, if you throw first bytes of mmc’s p2 into xxd it will be pretty obvious what’s happening
root@milkv-jupiter:~/env# cut -c1-10 env_p2.bin |xxd
00000000: 9fd3 0558 6172 6368 3d72 0a ...Xarch=r.
these 9f d3 05 58 are CRC bytes and have to be “aligned” with env’s contents; this is what mkenvimage takes care of.
Here’s my recipe to convert binary image to text and to binary back.
cat /dev/mmcblk0p2 > env_p2.bin
cut -c5- < env_p2.bin > env_nocrc.bin
tr '\0' '\n' < env_nocrc.bin > env_nonull.bin
tr -d '\377'< env_nonull.bin |sed '/^$/d' > env.txt
[do your stuff]
mkenvimage -s 16384 env.txt > env_p2.bin
cat env_p2.bin > /dev/mmcblk0p2
reboot
Guess it’s pretty self explanatory what’s happening here, i’ve split it into steps to maintain readability (it can be piped between staged or maybe one day i’ll make some unmkenv script;P)
Problem is that Jupiter’s u-boot compilation lacks of bootmenu command, therefore no possibility to make fancy menus like ‘boot to default kernel’, ‘run my custom gentoo image’.
Currently i am trying to boot extlinux which could solve this issue as this tandem i’ve successfully “exploited” on my R01 uConsole 
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Hi thanks for this. Do you know the exact commands to load Syslinux efi and grub2 then Linux kernel/Linux OS manually from u-boot directly? Thanks.
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