Re: [PATCH 2.6.21] cramfs: add cramfs Linear XIP

[Christoph Hellwig <hch@infradead.org>]

On Fri, Jun 08, 2007 at 09:50:17AM +0200, Carsten Otte wrote:
> I see your poing with regard to layering, and I agree to it.
> In order to do ioremap/iounmap at least we need a counterpart 
> put_xip_page thing to do iounmap in that path. Our dcss segments on 
> 390 did not raise that requirement: they had a permanent kernel mapping.
> The quiz question to me is: why don't we establish a permanenet 
> mapping of the entire thing from mount() to unmount(). That eliminates 
> the need to do iomap/iounmap, eliminates the need to have 
> put_xip_page, and eliminates to care about what layer would do this. 
> Would work for cramfs, won't work for read+write flash filesystems.

Jared's patch currently does ioremap on mount (and no iounmap at all).
That mapping needs to move from the filesystem to the device driver.