linux-kernel - Re: [patch] paravirt: isolate module ops

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Message-ID: <20070107183946.GB8158@infradead.org>
Date:	Sun, 7 Jan 2007 18:39:46 +0000
From:	Christoph Hellwig <hch@...radead.org>
To:	Christoph Hellwig <hch@...radead.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Ingo Molnar <mingo@...e.hu>, Zachary Amsden <zach@...are.com>,
	Jeremy Fitzhardinge <jeremy@...source.com>,
	Chris Wright <chrisw@...s-sol.org>,
	Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org,
	Arjan van de Ven <arjan@...radead.org>,
	Adrian Bunk <bunk@...sta.de>, airlied@...ux.ie
Subject: Re: [patch] paravirt: isolate module ops

On Sat, Jan 06, 2007 at 07:31:52PM +0000, Christoph Hellwig wrote:
> On Sun, Jan 07, 2007 at 03:18:45AM +1100, Rusty Russell wrote:
> > PS.  drm_memory.h has a "drm_follow_page": this forces us to uninline
> > various page tables ops.  Can this use follow_page() somehow, or do we
> > need an "__follow_page" export for this case?
> 
> Not if avoidable.  And it seems avoidable as drm really should be using
> vmalloc_to_page.  Untested patch below:

Even better we can actualy avid most of the page table walks completely.
First there is a number of places that can never have the vmalloc case
an may use ioremap/iounmap directly.  Secondly drm_core_ioremap/
drm_core_ioremapfree already have the right drm_map to check wich kind
of mapping we have - we just need to use it instead of discarding that
information!  The only leaves direct drm_ioremapfree in i810_dma.c and
i830_dma.c which I don't quite manage to follow.  Maybe Dave has an
idea how to get rid of those aswell.

View attachment "drm-avoid-drm_ioremap" of type "text/plain" (1987 bytes)

View attachment "simplify-drm_core_ioremap" of type "text/plain" (2817 bytes)