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

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Date:	Tue, 19 Apr 2011 10:34:04 +0200
From:	Alexander Holler <holler@...oftware.de>
To:	Mike Frysinger <vapier.adi@...il.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/1] Implement /dev/byte (a generic byte source similiar
 to /dev/zero)

Am 18.04.2011 15:57, schrieb Mike Frysinger:
> On Mon, Apr 18, 2011 at 07:37, Alexander Holler wrote:
>> I don't know if this patch qualifies for inclusion into the mainline kernel, but
>> maybe someone else would be interested in such, so I'm posting it here.
>>
>> The main idea for that device was to have a source for 0xff to clear FLASH based
>> devices. And to make it more generic, I've added the possibility to change the
>> default value on a per file descriptor basis.
>>
>> I don't want to discuss if such a device makes sense or if such should be done
>> in userspace only. I like it as a device, otherwise I wouldn't have written it.
>> So besides this message, I will not take part in such a discussion.
>
> cant you do this with cuse ?  that would satisfy the "has to be a
> device" requirement while keeping it in userspace.

I know almost nothing about cuse, but I assume it should be possible to 
build such a device with cuse too.

> although, i have a hard time seeing there be a realistic perf diff with:
> tr '\000' '\377'<  /dev/zero | dd ......

There are many other ways to achieve such in userspace (even without 
using /dev/zero) and I want to avoid such a discussion.

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. ;)

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.

Regards,

Alexander Holler
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