Re: secure file deletion/SECRM support for JFFS2 and UBIFS

[Richard Weinberger <richard@nod.at>]

Am 27.04.2016 um 23:49 schrieb Chris Packham:
> On 04/27/2016 07:06 PM, Richard Weinberger wrote:
>> On Wed, Apr 27, 2016 at 9:05 AM, Richard Weinberger
>> <richard.weinberger@gmail.com> wrote:
>>>> Is that something people on this list would be interested in? I realize
>>>> JFFS2 is kind of in a twilight phase but we're really not able to
>>>> migrate some customers away from it.
>>>
>>> This is definitely a nice feature.
>>> But please keep in mind that you can overwrite data on flash. :-)
>>
>> Should be read "can't", of course...
>>
> 
> You can't overwrite with arbitrary data. But for NOR flash at least you 
> _can_ overwrite with 0 (at least I think you can). In other words if the 
> erased state is 0xff you can write 0xaa you would not be able to write 
> 0x55 without erasing the block first but you would be able to write 0x00.
> 
> I was hoping to avoid having to do an immediate erase but if I'm wrong 
> that's what we'd have to do.

Well, UBIFS and JFFS2 work on generic MTD, so having a special hack for NOR
is not really what we want.

Thanks,
//richard