[PATCH -tip 0/6 V4] tracing: kprobe-based event tracer

[Avi Kivity]

Ingo Molnar wrote:
>> kvm has three requirements not needed by kprobes:
>> - it wants to execute instructions, not just decode them, including  
>>   generating faults where appropriate
>> - it is performance critical
>> - it needs to support 16-bit, 32-bit, and 64-bit instructions simultaneously
>>
>> If an arch/x86/ decoder/emulator gives me these I'll gladly switch 
>> to it.  x86_emulate.c is high on my list of most disliked code.
>>     
>
> Well, this has to be driven from the KVM side as the kprobes use 
> will only be for decoding so if it's modified from the kprobes side 
> the KVM-only functionality might regress.
>
> So ... we can do the library decoder for kprobes purposes, and 
> someone versed in the KVM emulator can then combine the two.
>   

Problem is, anyone versed in the kvm emulator will want to run as far 
away from this work as possible.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.