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

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Message-ID: <4DAD5046.3030008@ahsoftware.de>
Date:	Tue, 19 Apr 2011 11:05:10 +0200
From:	Alexander Holler <holler@...oftware.de>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
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)

Hello,

Am 19.04.2011 10:44, schrieb Alan Cox:
>> 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.

Thanks for the explanation.

>> 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.

I thought about that too, but that would have been to easy (and static). ;)

And the usage of file descriptors was the only idea I've come up with, 
which is multitasking and multiuser aware.

Regards,

Alexander
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