semantic: 0.163
debug: 0.144
graphic: 0.117
device: 0.103
boot: 0.094
other: 0.074
PID: 0.058
vnc: 0.049
performance: 0.045
files: 0.043
permissions: 0.036
network: 0.032
socket: 0.031
KVM: 0.011
debug: 0.464
boot: 0.438
other: 0.014
files: 0.013
device: 0.012
network: 0.010
socket: 0.010
PID: 0.009
semantic: 0.007
performance: 0.007
vnc: 0.006
graphic: 0.004
KVM: 0.003
permissions: 0.003

unable to boot arm64 image

Hi

Now I facing boot linux-5.3 arm64 image failed, without any log, just hang here.

Host machine: ubuntu-18.04 with 4.15.0-70-generic kernel
Qemu version: qemu-system-aarch64-version 4.1.0
use command: qemu-system-aarch64 -kernel <IAMGE> -append "console=ttyAMA0" -m 2048M -smp 2 -M virt -cpu cortex-a57 -nographic

could anyone teach me how to debug this?

You don't say anything about the kernel image you're trying to boot, but "nothing happens" is the expected result of trying to run a kernel which is not correctly configured to run on QEMU. You can debug in the same way you would debug "my kernel didn't boot on real hardware": try the gdb debugstub, try looking at the kernel config and comparing against a working version, etc.

https://translatedcode.wordpress.com/2017/07/24/installing-debian-on-qemus-64-bit-arm-virt-board/ is an example of a working setup of an aarch64 guest, which is probably a good place to start.