From: Ingo Molnar <mingo@elte.hu>
To: Avi Kivity <avi@redhat.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andi Kleen <andi@firstfloor.org>,
Jim Keniston <jkenisto@us.ibm.com>,
kvm@vger.kernel.org, systemtap-ml <systemtap@sources.redhat.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -tip 0/6 V4] tracing: kprobe-based event tracer
Date: Fri, 3 Apr 2009 14:26:54 +0200 [thread overview]
Message-ID: <20090403122654.GA19451@elte.hu> (raw)
In-Reply-To: <49D5FE42.5080100@redhat.com>
* Avi Kivity <avi@redhat.com> wrote:
> 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.
Are you suggesting that the KVM emulator should never have been
merged in the first place? ;-)
Anyway, we'll make sure the kprobes/library decoder is as clean as
possible - so it ought to be hackable and extensible without the
risk of permanent brain damage. Mmiotrace and kmemcheck has decoding
smarts too, and i think the sw-breakpoint injection code of KGDB
could use it as well - so there's broader utility in all this.
Ingo
next prev parent reply other threads:[~2009-04-03 12:28 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-02 17:24 [PATCH -tip 0/6 V4] tracing: kprobe-based event tracer Masami Hiramatsu
2009-04-03 11:26 ` Ingo Molnar
2009-04-03 11:32 ` Andi Kleen
2009-04-03 11:50 ` Avi Kivity
2009-04-03 12:12 ` Ingo Molnar
2009-04-03 12:17 ` Avi Kivity
2009-04-03 12:26 ` Ingo Molnar [this message]
2009-04-03 12:33 ` Avi Kivity
2009-04-03 13:16 ` Vegard Nossum
2009-04-03 13:40 ` Avi Kivity
2009-04-03 13:52 ` Masami Hiramatsu
2009-04-05 19:37 ` Pekka Paalanen
2009-04-06 7:53 ` Avi Kivity
2009-04-03 12:25 ` Andi Kleen
2009-04-03 14:21 ` Masami Hiramatsu
2009-04-03 14:23 ` Ingo Molnar
2009-04-03 16:55 ` Masami Hiramatsu
2009-04-03 17:59 ` Jim Keniston
2009-04-03 14:30 ` Avi Kivity
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