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Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU back
From: |
Lluís Vilanova |
Subject: |
Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel |
Date: |
Wed, 07 Dec 2011 19:35:31 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.0.92 (gnu/linux) |
Anthony Liguori writes:
[...]
> Why should this analyzer live outside of QEMU in the first place? I fail to
> see
> the rationale for that other than not wanting to do the work of making it
> suitable for upstream consumption.
For the same reason that SystemTap lets you add user-provided code into the
trace hooks, you never know what the user actually wants. The difference is that
when dealing with traces that require a high bandwidth, different people may be
interested on analyzing different events and under different conditions, and
having a JIT in QEMU comes in handy to optimize the traces. This includes the
generation of extra tracing code at translation time (e.g., I generate checks in
TCG to establish when I want to trace a specific event, and someone else may
just want to increment a counter using TCG code).
Guest trace instrumentation turns QEMU into a highly-performant tool for dynamic
binary instrumentation, with all the benefits that stem from QEMU (support for a
myriad of target architectures, as well as support for both full-system and
user-level applications).
I can understand if someone thinks this is not a desired feature for QEMU [1],
but not including it into upstream will just turn it into a patch-based feature
that will rapidly fail to apply on top of upstream QEMU.
[1] Of course, I will still contribute support for guest tracing, as well as the
guest events I added.
Lluis
--
"And it's much the same thing with knowledge, for whenever you learn
something new, the whole world becomes that much richer."
-- The Princess of Pure Reason, as told by Norton Juster in The Phantom
Tollbooth
- Re: [Qemu-devel] Insane virtio-serial semantics, (continued)
- [Qemu-devel] [PATCH v2 5/5] backdoor: Add guest-side library, Lluís Vilanova, 2011/12/05
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Anthony Liguori, 2011/12/06
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Lluís Vilanova, 2011/12/07
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Anthony Liguori, 2011/12/07
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Lluís Vilanova, 2011/12/07
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Anthony Liguori, 2011/12/07
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Lluís Vilanova, 2011/12/07
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Anthony Liguori, 2011/12/07
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel,
Lluís Vilanova <=
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Peter Maydell, 2011/12/07
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Anthony Liguori, 2011/12/07
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Lluís Vilanova, 2011/12/07
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Lluís Vilanova, 2011/12/07
- Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Blue Swirl, 2011/12/08
Re: [Qemu-devel] [PATCH v2 0/5] backdoor: lightweight guest-to-QEMU backdoor channel, Stefan Hajnoczi, 2011/12/08