svn commit: r265132 - in head: share/man/man4 sys/dev/null

[Steven Hartland]

----- Original Message ----- 
From: "Ian Lepore" <ian at FreeBSD.org>
To: "Steven Hartland" <killing at multiplay.co.uk>
Cc: "Eitan Adler" <eadler at FreeBSD.org>; <src-committers at FreeBSD.org>; <svn-src-all at FreeBSD.org>; <svn-src-head at FreeBSD.org>
Sent: Wednesday, April 30, 2014 6:13 PM
Subject: Re: svn commit: r265132 - in head: share/man/man4 sys/dev/null


> On Wed, 2014-04-30 at 17:22 +0100, Steven Hartland wrote:
>> ----- Original Message ----- 
>> From: "Ian Lepore" <ian at FreeBSD.org>
>> To: "Eitan Adler" <eadler at FreeBSD.org>
>> Cc: <src-committers at FreeBSD.org>; <svn-src-all at FreeBSD.org>; <svn-src-head at FreeBSD.org>
>> Sent: Wednesday, April 30, 2014 3:48 PM
>> Subject: Re: svn commit: r265132 - in head: share/man/man4 sys/dev/null
>> 
>> 
>> > On Wed, 2014-04-30 at 06:20 +0000, Eitan Adler wrote:
>> >> Author: eadler
>> >> Date: Wed Apr 30 06:20:48 2014
>> >> New Revision: 265132
>> >> URL: http://svnweb.freebsd.org/changeset/base/265132
>> >> 
>> >> Log:
>> >>   Add a /dev/full device.
>> >>   
>> >>   /dev/full is similar to /dev/zero except it always returns
>> >>   ENOSPC when you attempt to write to it.
>> >>   
>> > 
>> > For some reason this reminded me of something I've been wanting for a
>> > while but never get around to writing... /dev/ones, it's just
>> > like /dev/zero except it returns 0xff bytes.  Useful for dd'ing to wipe
>> > out flash-based media.
>> 
>> Surely for that you want camcontrol security ...?
>> 
>>     Regards
>>     Steve
> 
> I have no idea what that is, but given that it has "security" in the
> name, it's almost certainly NOT what I want in any way shape or form.
> Shocking as it may be, some people are just not obsessed with security,
> for good reason.  It just isn't a consideration in any way in my day to
> day activities.  

Its a standard option which allows you to erase the contents of a device
its named security as thats the class of the ATA commands which provides
this functionality.

> When I want to make an sdcard, or some portion thereof, look
> empty/virgin/new-from-factory for testing on an embedded system, that
> has nothing to do with security, and everything to do with just exactly
> what I asked for:  something that writes all-ones-bits.

That does kind of describe the functionality thats provided by camcontrol
security appart from it explicity asks for the cells to be erased, so
results in the device being as close to from factory as possible but,
not set to a specific value. Maybe thats the difference between ATA based
flash media e.g. SSD and sdcard's?

    Regards
    Steve