rpi4: How to use armv7 dts on aarch64?

[mmirate]

I have some hardware which, on armv7 with the patchy kernel, works with a dts that is compiled and placed in /boot/overlays.

How should I alter the dts, and procedures for compiling/installing the dtb, to get the hardware working on linux-aarch64?

[graysky]

Not sure how you are providing the custom files. Is there a reason you can't just build them for aarch64 and supply them the same way?

[mmirate]

The custom file is a device-tree specification, similar to https://github.com/watterott/RPi-Display/blob/master/software/rpi-display-overlay.dts. On a Raspbian system ... after one finishes puking at Raspbian's kernel patches and Debian-based userland ... one is then supposed to incant "dtc -@ -I dts -O dtb -o rpi-display.dtbo rpi-display.dts", place the resulting file "rpi-display.dtbo" in /boot/overlays, and add a corresponding "dtoverlay=..." line to /boot/config.txt.

On a fresh install of the aarch64 image, even after a "pacman -Syu", that directory does not exist; when I create it, place the file there, modify /boot/config.txt and reboot, the overlay appears to have no effect. And when I try https://archlinuxarm.org/forum/viewtopic.php?f=23&t=14544&sid=763f4a7e57c0ec163e0725962687efe5#p64371, the system fails to boot because u-boot doesn't recognize the "bootz" command.

[mmirate]

So apparently "bootz" is inapplicable on arm64 because for (insert reasons here) linux can't do its self-extracting magic-tricks on arm64 like it can on armv7 et al.

Which, so far, knock on wood, narrows my question: given a "bootz" incantation, how do I determine an equivalent "booti" incantation?

[mmirate]

And, to narrow things even further: how do I make the initramfs image agreeable to "booti"?

[mmirate]

Okay, so I finally got it to where using u-boot's fdt subsystem would boot the system. I even got a hopeful-looking output from the custom hardware.

But, at the same time, it also somehow booted without i2c support, which caused it to be unable to communicate with the custom battery system, which caused the battery system to powercycle it, and after reapplying power, it hung at the splash screen (i.e. https://elinux.org/R-Pi_Troubleshooting#Coloured_splash_screen), and I don't have another ALARM-based Pi with which to redo the kernel image.

Now what?

[mmirate]

Well? Is this a forum or just an echo-chamber!?