[MT6739][AOSP 8.1]Audio related bootloop

[sqhills]

Current Behavior:

Device stuck in bootanimation, adbd works. logcat shows something about audio@2.0-servi getting a SIGSEGV.
Tried to disable audio effects in build.prop but to no avail.

Describe the bug

Some kind of audio service is preventing boot.

To Reproduce

1. flash the image via fastboot
2. fastboot -w
3. reboot
4. stuck on bootanimation

Smartphone (please complete the following information):

• Device: YDD011
• Build Flavor: system-arm64-aonly-vanilla-nosu.img.xz
• Version V32

Additional context

So, I've actually tried several Android versions, and so far AOSP 8.1 is the closest to functional. AOSP 9.0 reboots directly to fastboot, while AOSP 10.0 stucks on boot logo. AOSP 11 does reach the ANDROID animation but adbd doesn't start so no way to grab logs.
My device is more of a PDA rather than a phone. No LTE model, so nothing to do with that.
It's shipped with a stock 8.1 rom very similar to AOSP except for minor annoying modifications. Treble Check shows that it's aonly with vndk v27 and non SAR.
I'm using magisk patched boot image to bypass dm-verity or else it bootloops at the boot logo.
logs attached:(after disabling audio effects)
logcat.log

Thanks in advance. :)

[phhusson]

My AOSP8.1 was really completely a work-in-progress. I'd rather look at logs on AOSP 10.

[sqhills]

Last time I tired, AOSP 10 stucks at boot logo(the bootloader one). Perhaps I got something wrong. I will try again nevertheless.

[phhusson]

Even if it's stuck at boot logo I can look at logs.

[sqhills]

It's literally the bootloader logo, so android wasn't loaded yet. I'm sure I must have botched the flashing or something. I'll try it again.

[sqhills]

By the way, previously when I tired AOSP 11, the device booted into bootanimation, yet adbd didn't start. Am I still able to grab logs under this circumstance?

[sqhills]

OK, so I tried AOSP 10 v222 again, and ended up with the same result. On boot, device only displays the boot logo (not ANDROID but the vendor one). However, I checked with twrp and found that files were generated in /data, which means android did start. I wasn't able to locate any logs, though. Is there any way to obtain logs in this situation? Thanks.

[phhusson]

From TWRP grab logs from /sys/fs/pstore or /proc/last_kmsg
If you have a /sys/fs/pstore folder but it's empty, open a terminal in twrp and do mount -t pstore none /sys/fs/pstore

[sqhills]

Got it!
last_kmsg

pstore/
├─ console-ramoops
├─ console-ramoops-2
├─ pmsg-ramoops-0