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From: Jeff Dike <jdike@addtoit.com>
To: BlaisorBlade <blaisorblade_spam@yahoo.it>
Cc: user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] Re: [uml-user] /dev/anon available
Date: Sat, 17 Jan 2004 23:54:39 -0500	[thread overview]
Message-ID: <20040118045439.GE8571@ccure.user-mode-linux.org> (raw)
In-Reply-To: <200401172048.47847.blaisorblade_spam@yahoo.it>

On Sat, Jan 17, 2004 at 08:48:47PM +0100, BlaisorBlade wrote:
> I've given a look to the page, but yet I cannot see (this can be for my fault, 
> but I'd really like an explaination of this) why you couldn't just mmap 
> /dev/zero with MAP_PRIVATE to get the behaviour you want to get from 
> /dev/anon (or maybe using MAP_ANONYMOUS). 

Because when you map a /dev/zero page, modify it, then map it (i.e. the same
offset and the same fd) again someplace else, you don't get the modifications.
You get a page full of zeros.   This obviously breaks the UML VM system.

				Jeff


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  reply	other threads:[~2004-01-18  4:32 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <200401130510.i0D5AlS4026784@ccure.user-mode-linux.org>
2004-01-17 19:48 ` [uml-devel] Re: [uml-user] /dev/anon available BlaisorBlade
2004-01-18  4:54   ` Jeff Dike [this message]
2004-01-18 16:13     ` BlaisorBlade
2004-01-18 23:53       ` Jeff Dike
2004-01-20 19:32         ` BlaisorBlade

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