Bug 47011

Summary:	/dev/one character device
Product:	Drivers	Reporter:	Robin Bankhead (kernel)
Component:	Other	Assignee:	drivers_other
Status:	RESOLVED WILL_NOT_FIX
Severity:	enhancement	CC:	alan
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	3.5.3	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	Patch to drivers/char/mem.c to create a /dev/one device

Description Robin Bankhead 2012-09-04 12:54:25 UTC

Created attachment 79221 [details]
Patch to drivers/char/mem.c to create a /dev/one device

Apologies if this has been discussed and vetoed already, couldn't find anything here or on LKML.

I think it would be useful for the kernel to have a /dev/one device (supplying a stream of binary 1) to complement /dev/zero. The primary use-case would be for implementation of certain state- and guru-endorsed disk erasure algorithms, including

- Canadian RCMP TSSIT OPS-II (7 passes)
- German VSITR (7 passes)
- Bruce Schneier (7 passes)

Other uses may present themselves, but this alone seems compelling.

The attached patch is only minimally my work, I adapted it from an old one I found here:
http://www.linuxquestions.org/questions/linux-newbie-8/is-there-a-dev-one-like-dev-zero-619626/

Hope this is of some interest.

Comment 1 Alan 2012-09-04 14:56:22 UTC

This was rejected - you can do it lots of other ways. The zero on the other hand is very useful for mappings when handling memory allocation so has a kernel side use.

Also note that because of bad sector remapping on any vaguely modern rotating disk , and because SSDs work entirely differently no number of passes of writing data are guaranteed to erase a disk. You should be using the disk level secure erase feature and command set via hdparm or similar tools. Your drive vendor should be able to confirm the certifications they meet.