qemu ftrace howto

qemu 1.5  add support for using ftrace as a backend for tracing


howto:

1

./configure --trace-backend=ftrace

2

echo 1 > /sys/kernel/debug/tracing/events/kvm/enable

3 a predefine events list:

cat /home/events

 *

4 enable trace filter in qemu

./qemu-system-x86_64 -enable-kvm -trace events=/home/events

5 example output:

less /sys/kernel/debug/tracing/trace snip qemu-system-x86-23226 [002] d... 116142.685922: kvm_entry: vcpu 0  
qemu-system-x86-23226 [002] d... 116142.685923: kvm_exit: reason IO_INSTRUCTION rip 0xc45b info 700040 0  
qemu-system-x86-23226 [002] .... 116142.685924: kvm_pio: pio_write at 0x70 size 1 count 1 

snip