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Date: Tue, 28 Aug 2012 17:50:25 +0200
From: Luigi Rizzo <rizzo@iet.unipi.it>
To: John Baldwin <jhb@freebsd.org>
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Cc: freebsd-current@freebsd.org, current@freebsd.org,
	Andriy Gapon <avg@freebsd.org>
Subject: Re: per file descriptor device callbacks ?
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On Mon, Aug 27, 2012 at 12:27:54PM -0400, John Baldwin wrote:
> On Monday, August 27, 2012 3:55:47 am Andriy Gapon wrote:
> > on 27/08/2012 10:34 Luigi Rizzo said the following:
> > > This requires to track calls to open/ioctl/poll/mmap/close.
> > > The difficulty i have is with mmap() and close(), because FreeBSD
> > > seems to handle these calls per-cdev rather than per-file-descriptor
> > > (for instance, no 'struct file' argument is available in mmap(), and
> > > the d_close method is only called on the last close() on the device).
> > 
> > devfs_set_cdevpriv(9), etc
> 
> mmap() is still problematic, but if you have the freedom to create your
> own VM objects, then d_mmap_single() can let you handle that fairly
> easily.

Would dev_clone(9) be a better way to do what i need ?

This way the struct cdev would be unique per file descriptor,
could be used as a key on the page fault callbacks
(i still do not have callbacks on dev_pager_ctor/dtor though).

cheers
luigi