下面是trace扩展的项目地址：
如果已经编译安装过crash，可以直接编译，然后使用extend工具加载.
加载模块
crash> extend /mnt/crash-trace/trace.so
/mnt/crash-trace/trace.so: shared object loaded
crash> extend
SHARED OBJECT COMMANDS
/mnt/crash-trace/trace.so trace
输出缓冲区数据
crash> trace show
...
cpus=8
bash-461 [002] 548.086834: function: mutex_unlock
bash-461 [002] 548.086847: function: __mutex_unlock_slowpath
bash-461 [002] 548.086849: function: preempt_count_add
bash-461 [002] 548.086849: function: rcu_read_lock_any_held
bash-461 [002] 548.086849: function: rcu_read_lock_held_common
bash-461 [002] 548.086849: function: rcu_lockdep_current_cpu_online
bash-461 [002] 548.086849: function: preempt_count_sub
bash-461 [002] 548.086850: function: syscall_exit_to_user_mode_prepare
bash-461 [002] 548.086850: function: exit_to_user_mode_prepare
bash-461 [002] 548.086851: function: fpregs_assert_state_consistent
bash-461 [002] 548.086851: function: switch_fpu_return
bash-461 [002] 548.086862: function: __x64_sys_dup2
导出到trace.dat
crash> trace dump -t
# trace-cmd report
...
cpus=8
bash-461 [002] 548.086834: function: mutex_unlock
bash-461 [002] 548.086847: function: __mutex_unlock_slowpath
bash-461 [002] 548.086849: function: preempt_count_add
bash-461 [002] 548.086849: function: rcu_read_lock_any_held
bash-461 [002] 548.086849: function: rcu_read_lock_held_common
bash-461 [002] 548.086849: function: rcu_lockdep_current_cpu_online
bash-461 [002] 548.086849: function: preempt_count_sub
bash-461 [002] 548.086850: function: syscall_exit_to_user_mode_prepare
卸载
crash> extend /mnt/crash-trace/trace.so -u
/mnt/crash-trace/trace.so: shared object unloaded