linux-kernel - Re: [PATCH 0/1] Implement /dev/byte (a generic byte source similiar to /dev/zero)

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Message-ID: <20110419094436.0b667410@lxorguk.ukuu.org.uk>
Date:	Tue, 19 Apr 2011 09:44:36 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Alexander Holler <holler@...oftware.de>
Cc:	Mike Frysinger <vapier.adi@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/1] Implement /dev/byte (a generic byte source similiar
 to /dev/zero)

> As for /dev/zero there are many other possible reasons to use such a 
> device, besides filling something with a value. For me it's as 
> reasonable as dev/zero, just that it offers a bit more flexibility and 
> provides another, at least for me useful, default value. Maybe 
> /dev/nzero would have been a good name too. ;)

/dev/zero exists not to put \0's into files as such but because it is
very useful to be able to map the zero page (a read only, or
copy-on-write blank page) into programs. The mmap is the reason it is
there.

> But I don't really care about inclusion into the kernel, it's just 
> something I had lying around (and needed only marginally work to 
> finalize as a proper patch) and I thought someone else could find it 
> usefull and I should share that here.

Implementationwise I think I would have gone for allocating a new device
and range of 256 minors - that would avoid the funky stuff setting what
it fills with as you'd just fill with the minor number.

Alan
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