On 03/05/2018 13:32, Alexander Shishkin wrote: >> >> +/* Default is SYSTEM mode. */ >> +static int __read_mostly pt_mode = PT_MODE_SYSTEM; >> +module_param(pt_mode, int, S_IRUGO); > So, it's an explicit module parameter? One apparent problem with this > is that one would need to reload kvm module(s) to be able to use PT, > which is not ideal. If you want to do tracing system-wide, that by definition must disable guest tracing, so I think the module parameter is appropriate. The question is more, what is the best default. Paolo
