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From: Matt Mackall <mpm@selenic.com>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Pavel Roskin <proski@gnu.org>, Dave Airlie <airlied@gmail.com>,
	Pekka Paalanen <pq@iki.fi>,
	linux-kernel@vger.kernel.org, jbeulich@novell.com
Subject: Re: Replacement for page fault notifiers?
Date: Wed, 09 Jan 2008 20:03:10 -0600	[thread overview]
Message-ID: <1199930590.6245.104.camel@cinder.waste.org> (raw)
In-Reply-To: <20080109164241.7daa5770@laptopd505.fenrus.org>


On Wed, 2008-01-09 at 16:42 -0800, Arjan van de Ven wrote:
> On Wed, 9 Jan 2008 20:22:54 +0000
> Christoph Hellwig <hch@infradead.org> wrote:
> 
> > On Thu, Jan 10, 2008 at 06:58:23AM +1100, Benjamin Herrenschmidt
> > wrote:
> > > It's a sane thing to do, Christoph, I don't think it's a
> > > unreasonable request to put the hooks back in.
> > 
> > As said a few times before there's simply no way we're going to put
> > exactly that crap back.  For one the patch removed a whole lot of
> > crud from the kprobes code that simply isn't going to come back just
> > because there are some pagefault notifiers.  Second the page fault
> > notifiers were horribly implemented and quite inefficient.  And third
> > we're not going to put something in just for out of tree code.
> > 
> 
> I'm btw all in favor of making mmio tracing full fledged kernel infrastructure.
> This doesn't mean "notifier" imo; this means a real flag in the struct page,
> and then the page fault code can do
> 
> if (page->flags & FLAG_MMIO_TRACED)
> 	mmio_trace(page, regs, whatever..);

That makes it way too easy for drivers of questionable legality to just
clear that bit. Also, we've got a shortage of page bits, etc.

-- 
Mathematics is the supreme nostalgia of our time.


  parent reply	other threads:[~2008-01-10  2:03 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-08 19:06 Pekka Paalanen
2008-01-08 20:32 ` Christoph Hellwig
2008-01-08 22:13   ` Dave Airlie
2008-01-09  0:26     ` Benjamin Herrenschmidt
2008-01-09 18:18       ` Pavel Roskin
2008-01-09 18:21         ` Christoph Hellwig
2008-01-09 19:58           ` Benjamin Herrenschmidt
2008-01-09 20:22             ` Christoph Hellwig
2008-01-10  0:42               ` Arjan van de Ven
2008-01-10  0:47                 ` Andi Kleen
2008-01-10  0:55                   ` Arjan van de Ven
2008-01-10  0:58                     ` Benjamin Herrenschmidt
2008-01-10  1:01                     ` Andi Kleen
2008-01-10  0:56                 ` Benjamin Herrenschmidt
2008-01-10  2:03                 ` Matt Mackall [this message]
2008-01-10  2:21                   ` Pavel Roskin
2008-01-10  2:30                     ` Matt Mackall
2008-01-10 18:44               ` Pekka Paalanen
2008-01-09 20:24             ` Pavel Roskin
2008-01-09 20:26               ` Christoph Hellwig
2008-01-09 20:41                 ` Pavel Roskin
2008-01-09 20:44                 ` Valdis.Kletnieks

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