device: 0.790
graphic: 0.537
socket: 0.488
permissions: 0.470
files: 0.458
performance: 0.449
network: 0.422
vnc: 0.411
semantic: 0.395
boot: 0.302
debug: 0.279
PID: 0.202
other: 0.068
KVM: 0.065

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