device: 0.889
graphic: 0.884
other: 0.732
semantic: 0.623
instruction: 0.591
mistranslation: 0.480
vnc: 0.396
network: 0.372
socket: 0.287
KVM: 0.282
boot: 0.260
assembly: 0.040

undefined address access cause failure
Description of problem:
Hi,
I used serial device as below:
qemu/hw/char/serial.c
It defines only support 8 registers address space(offset 0x00-0x32). And in guest os, the hardware is synopsys dw_apb_uart which is compatible with 16550.
when it access low 8 registers, it works ok. but it may access high address(0x8c) which serial.c not defined, then fail occur.

Is there anyway to handle this, access address which device not defined, expect it no handle, but not cause system crash. like read is zero and write ignore.