linux-kernel - Re: [PATCH] [5/12] x86_64: Make patching more robust, fix paravirt issue

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Message-ID: <5d6222a80708210030w26294b0dq4bd1977fcb3bc6f4@mail.gmail.com>
Date:	Tue, 21 Aug 2007 04:30:10 -0300
From:	"Glauber de Oliveira Costa" <glommer@...il.com>
To:	"Jeremy Fitzhardinge" <jeremy@...p.org>
Cc:	"Chris Wright" <chrisw@...s-sol.org>,
	"Rusty Russell" <rusty@...tcorp.com.au>, "Andi Kleen" <ak@...e.de>,
	patches@...-64.org, linux-kernel@...r.kernel.org,
	"Linus Torvalds" <torvalds@...ux-foundation.org>,
	"Steven Rostedt" <rostedt@...dmis.org>
Subject: Re: [PATCH] [5/12] x86_64: Make patching more robust, fix paravirt issue

On 8/20/07, Jeremy Fitzhardinge <jeremy@...p.org> wrote:
> Chris Wright wrote:
> > That did get backed out (at least the part that broke paravirt patching)
> > in 602033ed5907a59ce86f709082a35be047743a86.  Linus' tree should be
> > working fine right now with d34fda4a84c18402640a1a2342d6e6d9829e6db7
> > committed, and can be further refined with the patch below that's just
> > waiting on some further testing.
> >
>
> I don't think this is necessary.  It isn't worth complicating the
> interface to avoid the memcpy.
>
>     J
Damn,

I can't believe I've just lost a night tracking the issue, without
seeing the discussion here ;-)
I came out to this very same conclusion, and was about to send a patch
that fixes it, by doing a memcpy before starting the instruction
replacement.

(I wouldn't say anything, as this is solved, but my night have to get
some value, after all! ;-)

So I'm with Jeremy. We don't lose too much by putting a memcpy there,
this code is not exactly critical. It also seems cleaner, and less
error prone. I have a patch ready here, but I think by this time, you
guys have too ;-)

-- 
Glauber de Oliveira Costa.
"Free as in Freedom"
http://glommer.net

"The less confident you are, the more serious you have to act."
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