Troubleshooting • Re: Pi 5 serial output is buggy

I cannot produce the problem on Pi3 with identical -v8 kernel. I can produce on Pi5 with current rpi-update kernel.

I do not know how to downgrade kernel to test whether this really worked previously.

Many older kernel versions (separate Debian packages) are still available, so:will install the previous one. Or you might actually still have it installed, I did remove it for various reasons. Look in /boot for versions.

Also check (do binary diff ) what is actually loaded at boot (kernel8.img and initramfs8 files). Also DTBs are versioned, originals are in /usr/lib/linux-image-<version> or so. Copy manually or formal method is to run update-initramfs for a specific kernel version, that also calls a hook script which does that copying for you.If you have used rpi-update, do that for that version.

It still might be that the issue is in Pi5 firmware, so in EEPROM code and/or Cortex-M3.

It looks to me that there is some store-forward buffer/handler that misses some entry in a cyclic buffer or so. Maybe part is on M3, I have no clue.

Statistics: Posted by redvli — Mon Sep 16, 2024 6:49 pm

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