device: 0.790
ppc: 0.687
arm: 0.633
graphic: 0.537
socket: 0.488
permissions: 0.470
files: 0.458
performance: 0.449
register: 0.445
network: 0.422
vnc: 0.411
architecture: 0.406
semantic: 0.395
boot: 0.302
debug: 0.279
VMM: 0.216
PID: 0.202
risc-v: 0.174
peripherals: 0.152
TCG: 0.144
i386: 0.099
hypervisor: 0.083
user-level: 0.080
mistranslation: 0.080
KVM: 0.065
x86: 0.056
virtual: 0.035
kernel: 0.020
assembly: 0.015

windows serial COM PollingFunc don't sleep if guest uart can't write
Description of problem:
If two or more characters are sent from the host to the guest via Windows Com/Serial, everything freezes.
Steps to reproduce:
1.
2.
3.
Additional information:
I fix it in qemu/chardev/char-win.c see attached file