Re: How to do a mmap ?

[Erik Mouw <J.A.K.Mouw@its.tudelft.nl>]

On Wed, Feb 05, 2003 at 11:51:24PM +0100, Jerome de Vivie wrote:
> Erik Mouw wrote:
> > Using files from kernel mode is policy, while the kernel should only
> > implement mechanisms. Rethink your design so the file usage is done
> > where it belongs: userland. This has the nice advantage that you can
> > get the same information from weird locations like a remote SQL
> > database by just rewriting the userland backend. There's no way to do
> > this from kernel.
> 
> The module implement a stackable filesystem (which should work over
> NFS). I use a file because i need to store persistant data and i also
> need to hide this file from userland. As I need to access some data very
> frequently, i prefer using direct memory operation than read/write. All
> thoses operations are protected by a mandatory. 

Persistent data really should be handled by a usermode helper, cause
the decision *where* to store it is policy. See for example how alsactl
handles the state of all ALSA soundcards in the system. See also how a
couple of USB devices get their firmware uploaded through a generic
device node.


Erik

-- 
J.A.K. (Erik) Mouw
Email: J.A.K.Mouw@its.tudelft.nl  mouw@nl.linux.org

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