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

From: Avi Kivity
Date: Fri Apr 03 2009 - 08:18:01 EST


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.

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